-#include "insn-flags.h"
-#include "insn-attr.h"
-#include "recog.h"
-#include "function.h"
-#include "expr.h"
-#include "real.h"
-#include "except.h"
-#include "toplev.h"
-
-/* ??? Eventually must record somehow the labels used by jumps
- from nested functions. */
-/* Pre-record the next or previous real insn for each label?
- No, this pass is very fast anyway. */
-/* Condense consecutive labels?
- This would make life analysis faster, maybe. */
-/* Optimize jump y; x: ... y: jumpif... x?
- Don't know if it is worth bothering with. */
-/* Optimize two cases of conditional jump to conditional jump?
- This can never delete any instruction or make anything dead,
- or even change what is live at any point.
- So perhaps let combiner do it. */
-
-/* Vector indexed by uid.
- For each CODE_LABEL, index by its uid to get first unconditional jump
- that jumps to the label.
- For each JUMP_INSN, index by its uid to get the next unconditional jump
- that jumps to the same label.
- Element 0 is the start of a chain of all return insns.
- (It is safe to use element 0 because insn uid 0 is not used. */
-
-static rtx *jump_chain;
-
-/* Maximum index in jump_chain. */
-
-static int max_jump_chain;
-
-/* Set nonzero by jump_optimize if control can fall through
- to the end of the function. */
-int can_reach_end;
-
-/* Indicates whether death notes are significant in cross jump analysis.
- Normally they are not significant, because of A and B jump to C,
- and R dies in A, it must die in B. But this might not be true after
- stack register conversion, and we must compare death notes in that
- case. */
-
-static int cross_jump_death_matters = 0;
-
-static int init_label_info PARAMS ((rtx));
-static void delete_barrier_successors PARAMS ((rtx));
-static void mark_all_labels PARAMS ((rtx, int));
-static rtx delete_unreferenced_labels PARAMS ((rtx));
-static void delete_noop_moves PARAMS ((rtx));
-static int calculate_can_reach_end PARAMS ((rtx, int));
-static int duplicate_loop_exit_test PARAMS ((rtx));
-static void find_cross_jump PARAMS ((rtx, rtx, int, rtx *, rtx *));
-static void do_cross_jump PARAMS ((rtx, rtx, rtx));
-static int jump_back_p PARAMS ((rtx, rtx));
-static int tension_vector_labels PARAMS ((rtx, int));
-static void mark_jump_label PARAMS ((rtx, rtx, int, int));
-static void delete_computation PARAMS ((rtx));
-static void delete_from_jump_chain PARAMS ((rtx));
-static int delete_labelref_insn PARAMS ((rtx, rtx, int));
-static void mark_modified_reg PARAMS ((rtx, rtx, void *));
-static void redirect_tablejump PARAMS ((rtx, rtx));
-static void jump_optimize_1 PARAMS ((rtx, int, int, int, int, int));
-#if ! defined(HAVE_cc0) && ! defined(HAVE_conditional_arithmetic)
-static rtx find_insert_position PARAMS ((rtx, rtx));
-#endif
-static int returnjump_p_1 PARAMS ((rtx *, void *));
-static void delete_prior_computation PARAMS ((rtx, rtx));
-\f
-/* Main external entry point into the jump optimizer. See comments before
- jump_optimize_1 for descriptions of the arguments. */
-void
-jump_optimize (f, cross_jump, noop_moves, after_regscan)
- rtx f;
- int cross_jump;
- int noop_moves;
- int after_regscan;
-{
- jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, 0, 0);
-}
-
-/* Alternate entry into the jump optimizer. This entry point only rebuilds
- the JUMP_LABEL field in jumping insns and REG_LABEL notes in non-jumping
- instructions. */
-void
-rebuild_jump_labels (f)
- rtx f;
-{
- jump_optimize_1 (f, 0, 0, 0, 1, 0);
-}
-
-/* Alternate entry into the jump optimizer. Do only trivial optimizations. */
-void
-jump_optimize_minimal (f)
- rtx f;
-{
- jump_optimize_1 (f, 0, 0, 0, 0, 1);
-}
-\f
-/* Delete no-op jumps and optimize jumps to jumps
- and jumps around jumps.
- Delete unused labels and unreachable code.
-
- If CROSS_JUMP is 1, detect matching code
- before a jump and its destination and unify them.
- If CROSS_JUMP is 2, do cross-jumping, but pay attention to death notes.
-
- If NOOP_MOVES is nonzero, delete no-op move insns.
-
- If AFTER_REGSCAN is nonzero, then this jump pass is being run immediately
- after regscan, and it is safe to use regno_first_uid and regno_last_uid.
-
- If MARK_LABELS_ONLY is nonzero, then we only rebuild the jump chain
- and JUMP_LABEL field for jumping insns.
-
- If `optimize' is zero, don't change any code,
- just determine whether control drops off the end of the function.
- This case occurs when we have -W and not -O.
- It works because `delete_insn' checks the value of `optimize'
- and refrains from actually deleting when that is 0.
-
- If MINIMAL is nonzero, then we only perform trivial optimizations:
-
- * Removal of unreachable code after BARRIERs.
- * Removal of unreferenced CODE_LABELs.
- * Removal of a jump to the next instruction.
- * Removal of a conditional jump followed by an unconditional jump
- to the same target as the conditional jump.
- * Simplify a conditional jump around an unconditional jump.
- * Simplify a jump to a jump.
- * Delete extraneous line number notes.
- */
-
-static void
-jump_optimize_1 (f, cross_jump, noop_moves, after_regscan,
- mark_labels_only, minimal)
- rtx f;
- int cross_jump;
- int noop_moves;
- int after_regscan;
- int mark_labels_only;
- int minimal;
-{
- register rtx insn, next;
- int changed;
- int old_max_reg;
- int first = 1;
- int max_uid = 0;
- rtx last_insn;
-
- cross_jump_death_matters = (cross_jump == 2);
- max_uid = init_label_info (f) + 1;
-
- /* If we are performing cross jump optimizations, then initialize
- tables mapping UIDs to EH regions to avoid incorrect movement
- of insns from one EH region to another. */
- if (flag_exceptions && cross_jump)
- init_insn_eh_region (f, max_uid);
-
- if (! mark_labels_only)
- delete_barrier_successors (f);
-
- /* Leave some extra room for labels and duplicate exit test insns
- we make. */
- max_jump_chain = max_uid * 14 / 10;
- jump_chain = (rtx *) xcalloc (max_jump_chain, sizeof (rtx));
-
- mark_all_labels (f, cross_jump);
-
- /* Keep track of labels used from static data;
- they cannot ever be deleted. */
-
- for (insn = forced_labels; insn; insn = XEXP (insn, 1))
- LABEL_NUSES (XEXP (insn, 0))++;
-
- check_exception_handler_labels ();
-
- /* Keep track of labels used for marking handlers for exception
- regions; they cannot usually be deleted. */
-
- for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
- LABEL_NUSES (XEXP (insn, 0))++;
-
- /* Quit now if we just wanted to rebuild the JUMP_LABEL and REG_LABEL
- notes and recompute LABEL_NUSES. */
- if (mark_labels_only)
- goto end;
-
- if (! minimal)
- exception_optimize ();
-
- last_insn = delete_unreferenced_labels (f);
-
- if (noop_moves)
- delete_noop_moves (f);
-
- /* If we haven't yet gotten to reload and we have just run regscan,
- delete any insn that sets a register that isn't used elsewhere.
- This helps some of the optimizations below by having less insns
- being jumped around. */
-
- if (optimize && ! reload_completed && after_regscan)
- for (insn = f; insn; insn = next)
- {
- rtx set = single_set (insn);
-
- next = NEXT_INSN (insn);
-
- if (set && GET_CODE (SET_DEST (set)) == REG
- && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER
- && REGNO_FIRST_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
- /* We use regno_last_note_uid so as not to delete the setting
- of a reg that's used in notes. A subsequent optimization
- might arrange to use that reg for real. */
- && REGNO_LAST_NOTE_UID (REGNO (SET_DEST (set))) == INSN_UID (insn)
- && ! side_effects_p (SET_SRC (set))
- && ! find_reg_note (insn, REG_RETVAL, 0)
- /* An ADDRESSOF expression can turn into a use of the internal arg
- pointer, so do not delete the initialization of the internal
- arg pointer yet. If it is truly dead, flow will delete the
- initializing insn. */
- && SET_DEST (set) != current_function_internal_arg_pointer)
- delete_insn (insn);
- }
-
- /* Now iterate optimizing jumps until nothing changes over one pass. */
- changed = 1;
- old_max_reg = max_reg_num ();
- while (changed)
- {
- changed = 0;
-
- for (insn = f; insn; insn = next)
- {
- rtx reallabelprev;
- rtx temp, temp1, temp2 = NULL_RTX, temp3, temp4, temp5, temp6;
- rtx nlabel;
- int this_is_simplejump, this_is_condjump, reversep = 0;
- int this_is_condjump_in_parallel;
-
- next = NEXT_INSN (insn);
-
- /* See if this is a NOTE_INSN_LOOP_BEG followed by an unconditional
- jump. Try to optimize by duplicating the loop exit test if so.
- This is only safe immediately after regscan, because it uses
- the values of regno_first_uid and regno_last_uid. */
- if (after_regscan && GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
- && (temp1 = next_nonnote_insn (insn)) != 0
- && simplejump_p (temp1))
- {
- temp = PREV_INSN (insn);
- if (duplicate_loop_exit_test (insn))
- {
- changed = 1;
- next = NEXT_INSN (temp);
- continue;
- }
- }
-
- if (GET_CODE (insn) != JUMP_INSN)
- continue;
-
- this_is_simplejump = simplejump_p (insn);
- this_is_condjump = condjump_p (insn);
- this_is_condjump_in_parallel = condjump_in_parallel_p (insn);
-
- /* Tension the labels in dispatch tables. */
-
- if (GET_CODE (PATTERN (insn)) == ADDR_VEC)
- changed |= tension_vector_labels (PATTERN (insn), 0);
- if (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
- changed |= tension_vector_labels (PATTERN (insn), 1);
-
- /* See if this jump goes to another jump and redirect if so. */
- nlabel = follow_jumps (JUMP_LABEL (insn));
- if (nlabel != JUMP_LABEL (insn))
- changed |= redirect_jump (insn, nlabel);
-
- if (! optimize || ! minimal)
- continue;
-
- /* If a dispatch table always goes to the same place,
- get rid of it and replace the insn that uses it. */
-
- if (GET_CODE (PATTERN (insn)) == ADDR_VEC
- || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
- {
- int i;
- rtx pat = PATTERN (insn);
- int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
- int len = XVECLEN (pat, diff_vec_p);
- rtx dispatch = prev_real_insn (insn);
- rtx set;
-
- for (i = 0; i < len; i++)
- if (XEXP (XVECEXP (pat, diff_vec_p, i), 0)
- != XEXP (XVECEXP (pat, diff_vec_p, 0), 0))
- break;
-
- if (i == len
- && dispatch != 0
- && GET_CODE (dispatch) == JUMP_INSN
- && JUMP_LABEL (dispatch) != 0
- /* Don't mess with a casesi insn.
- XXX according to the comment before computed_jump_p(),
- all casesi insns should be a parallel of the jump
- and a USE of a LABEL_REF. */
- && ! ((set = single_set (dispatch)) != NULL
- && (GET_CODE (SET_SRC (set)) == IF_THEN_ELSE))
- && next_real_insn (JUMP_LABEL (dispatch)) == insn)
- {
- redirect_tablejump (dispatch,
- XEXP (XVECEXP (pat, diff_vec_p, 0), 0));
- changed = 1;
- }
- }
-
- /* If a jump references the end of the function, try to turn
- it into a RETURN insn, possibly a conditional one. */
- if (JUMP_LABEL (insn) != 0
- && (next_active_insn (JUMP_LABEL (insn)) == 0
- || GET_CODE (PATTERN (next_active_insn (JUMP_LABEL (insn))))
- == RETURN))
- changed |= redirect_jump (insn, NULL_RTX);
-
- reallabelprev = prev_active_insn (JUMP_LABEL (insn));
-
- /* Detect jump to following insn. */
- if (reallabelprev == insn && this_is_condjump)
- {
- next = next_real_insn (JUMP_LABEL (insn));
- delete_jump (insn);
- changed = 1;
- continue;
- }
-
- /* Detect a conditional jump going to the same place
- as an immediately following unconditional jump. */
- else if (this_is_condjump
- && (temp = next_active_insn (insn)) != 0
- && simplejump_p (temp)
- && (next_active_insn (JUMP_LABEL (insn))
- == next_active_insn (JUMP_LABEL (temp))))
- {
- /* Don't mess up test coverage analysis. */
- temp2 = temp;
- if (flag_test_coverage && !reload_completed)
- for (temp2 = insn; temp2 != temp; temp2 = NEXT_INSN (temp2))
- if (GET_CODE (temp2) == NOTE && NOTE_LINE_NUMBER (temp2) > 0)
- break;
-
- if (temp2 == temp)
- {
- delete_jump (insn);
- changed = 1;
- continue;
- }
- }
-
- /* Detect a conditional jump jumping over an unconditional jump. */
-
- else if ((this_is_condjump || this_is_condjump_in_parallel)
- && ! this_is_simplejump
- && reallabelprev != 0
- && GET_CODE (reallabelprev) == JUMP_INSN
- && prev_active_insn (reallabelprev) == insn
- && no_labels_between_p (insn, reallabelprev)
- && simplejump_p (reallabelprev))
- {
- /* When we invert the unconditional jump, we will be
- decrementing the usage count of its old label.
- Make sure that we don't delete it now because that
- might cause the following code to be deleted. */
- rtx prev_uses = prev_nonnote_insn (reallabelprev);
- rtx prev_label = JUMP_LABEL (insn);
-
- if (prev_label)
- ++LABEL_NUSES (prev_label);
-
- if (invert_jump (insn, JUMP_LABEL (reallabelprev)))
- {
- /* It is very likely that if there are USE insns before
- this jump, they hold REG_DEAD notes. These REG_DEAD
- notes are no longer valid due to this optimization,
- and will cause the life-analysis that following passes
- (notably delayed-branch scheduling) to think that
- these registers are dead when they are not.
-
- To prevent this trouble, we just remove the USE insns
- from the insn chain. */
-
- while (prev_uses && GET_CODE (prev_uses) == INSN
- && GET_CODE (PATTERN (prev_uses)) == USE)
- {
- rtx useless = prev_uses;
- prev_uses = prev_nonnote_insn (prev_uses);
- delete_insn (useless);
- }
-
- delete_insn (reallabelprev);
- changed = 1;
- }
-
- /* We can now safely delete the label if it is unreferenced
- since the delete_insn above has deleted the BARRIER. */
- if (prev_label && --LABEL_NUSES (prev_label) == 0)
- delete_insn (prev_label);
-
- next = NEXT_INSN (insn);
- }
-
- /* If we have an unconditional jump preceded by a USE, try to put
- the USE before the target and jump there. This simplifies many
- of the optimizations below since we don't have to worry about
- dealing with these USE insns. We only do this if the label
- being branch to already has the identical USE or if code
- never falls through to that label. */
-
- else if (this_is_simplejump
- && (temp = prev_nonnote_insn (insn)) != 0
- && GET_CODE (temp) == INSN
- && GET_CODE (PATTERN (temp)) == USE
- && (temp1 = prev_nonnote_insn (JUMP_LABEL (insn))) != 0
- && (GET_CODE (temp1) == BARRIER
- || (GET_CODE (temp1) == INSN
- && rtx_equal_p (PATTERN (temp), PATTERN (temp1))))
- /* Don't do this optimization if we have a loop containing
- only the USE instruction, and the loop start label has
- a usage count of 1. This is because we will redo this
- optimization everytime through the outer loop, and jump
- opt will never exit. */
- && ! ((temp2 = prev_nonnote_insn (temp)) != 0
- && temp2 == JUMP_LABEL (insn)
- && LABEL_NUSES (temp2) == 1))
- {
- if (GET_CODE (temp1) == BARRIER)
- {
- emit_insn_after (PATTERN (temp), temp1);
- temp1 = NEXT_INSN (temp1);
- }
-
- delete_insn (temp);
- redirect_jump (insn, get_label_before (temp1));
- reallabelprev = prev_real_insn (temp1);
- changed = 1;
- next = NEXT_INSN (insn);
- }
-
- /* Simplify if (...) x = a; else x = b; by converting it
- to x = b; if (...) x = a;
- if B is sufficiently simple, the test doesn't involve X,
- and nothing in the test modifies B or X.
-
- If we have small register classes, we also can't do this if X
- is a hard register.
-
- If the "x = b;" insn has any REG_NOTES, we don't do this because
- of the possibility that we are running after CSE and there is a
- REG_EQUAL note that is only valid if the branch has already been
- taken. If we move the insn with the REG_EQUAL note, we may
- fold the comparison to always be false in a later CSE pass.
- (We could also delete the REG_NOTES when moving the insn, but it
- seems simpler to not move it.) An exception is that we can move
- the insn if the only note is a REG_EQUAL or REG_EQUIV whose
- value is the same as "b".
-
- INSN is the branch over the `else' part.
-
- We set:
-
- TEMP to the jump insn preceding "x = a;"
- TEMP1 to X
- TEMP2 to the insn that sets "x = b;"
- TEMP3 to the insn that sets "x = a;"
- TEMP4 to the set of "x = b"; */
-
- if (this_is_simplejump
- && (temp3 = prev_active_insn (insn)) != 0
- && GET_CODE (temp3) == INSN
- && (temp4 = single_set (temp3)) != 0
- && GET_CODE (temp1 = SET_DEST (temp4)) == REG
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
- && (temp2 = next_active_insn (insn)) != 0
- && GET_CODE (temp2) == INSN
- && (temp4 = single_set (temp2)) != 0
- && rtx_equal_p (SET_DEST (temp4), temp1)
- && ! side_effects_p (SET_SRC (temp4))
- && ! may_trap_p (SET_SRC (temp4))
- && (REG_NOTES (temp2) == 0
- || ((REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUAL
- || REG_NOTE_KIND (REG_NOTES (temp2)) == REG_EQUIV)
- && XEXP (REG_NOTES (temp2), 1) == 0
- && rtx_equal_p (XEXP (REG_NOTES (temp2), 0),
- SET_SRC (temp4))))
- && (temp = prev_active_insn (temp3)) != 0
- && condjump_p (temp) && ! simplejump_p (temp)
- /* TEMP must skip over the "x = a;" insn */
- && prev_real_insn (JUMP_LABEL (temp)) == insn
- && no_labels_between_p (insn, JUMP_LABEL (temp))
- /* There must be no other entries to the "x = b;" insn. */
- && no_labels_between_p (JUMP_LABEL (temp), temp2)
- /* INSN must either branch to the insn after TEMP2 or the insn
- after TEMP2 must branch to the same place as INSN. */
- && (reallabelprev == temp2
- || ((temp5 = next_active_insn (temp2)) != 0
- && simplejump_p (temp5)
- && JUMP_LABEL (temp5) == JUMP_LABEL (insn))))
- {
- /* The test expression, X, may be a complicated test with
- multiple branches. See if we can find all the uses of
- the label that TEMP branches to without hitting a CALL_INSN
- or a jump to somewhere else. */
- rtx target = JUMP_LABEL (temp);
- int nuses = LABEL_NUSES (target);
- rtx p;
-#ifdef HAVE_cc0
- rtx q;
-#endif
-
- /* Set P to the first jump insn that goes around "x = a;". */
- for (p = temp; nuses && p; p = prev_nonnote_insn (p))
- {
- if (GET_CODE (p) == JUMP_INSN)
- {
- if (condjump_p (p) && ! simplejump_p (p)
- && JUMP_LABEL (p) == target)
- {
- nuses--;
- if (nuses == 0)
- break;
- }
- else
- break;
- }
- else if (GET_CODE (p) == CALL_INSN)
- break;
- }
-
-#ifdef HAVE_cc0
- /* We cannot insert anything between a set of cc and its use
- so if P uses cc0, we must back up to the previous insn. */
- q = prev_nonnote_insn (p);
- if (q && GET_RTX_CLASS (GET_CODE (q)) == 'i'
- && sets_cc0_p (PATTERN (q)))
- p = q;
-#endif
-
- if (p)
- p = PREV_INSN (p);
-
- /* If we found all the uses and there was no data conflict, we
- can move the assignment unless we can branch into the middle
- from somewhere. */
- if (nuses == 0 && p
- && no_labels_between_p (p, insn)
- && ! reg_referenced_between_p (temp1, p, NEXT_INSN (temp3))
- && ! reg_set_between_p (temp1, p, temp3)
- && (GET_CODE (SET_SRC (temp4)) == CONST_INT
- || ! modified_between_p (SET_SRC (temp4), p, temp2))
- /* Verify that registers used by the jump are not clobbered
- by the instruction being moved. */
- && ! regs_set_between_p (PATTERN (temp),
- PREV_INSN (temp2),
- NEXT_INSN (temp2)))
- {
- emit_insn_after_with_line_notes (PATTERN (temp2), p, temp2);
- delete_insn (temp2);
-
- /* Set NEXT to an insn that we know won't go away. */
- next = next_active_insn (insn);
-
- /* Delete the jump around the set. Note that we must do
- this before we redirect the test jumps so that it won't
- delete the code immediately following the assignment
- we moved (which might be a jump). */
-
- delete_insn (insn);
-
- /* We either have two consecutive labels or a jump to
- a jump, so adjust all the JUMP_INSNs to branch to where
- INSN branches to. */
- for (p = NEXT_INSN (p); p != next; p = NEXT_INSN (p))
- if (GET_CODE (p) == JUMP_INSN)
- redirect_jump (p, target);
-
- changed = 1;
- next = NEXT_INSN (insn);
- continue;
- }
- }
-
- /* Simplify if (...) { x = a; goto l; } x = b; by converting it
- to x = a; if (...) goto l; x = b;
- if A is sufficiently simple, the test doesn't involve X,
- and nothing in the test modifies A or X.
-
- If we have small register classes, we also can't do this if X
- is a hard register.
-
- If the "x = a;" insn has any REG_NOTES, we don't do this because
- of the possibility that we are running after CSE and there is a
- REG_EQUAL note that is only valid if the branch has already been
- taken. If we move the insn with the REG_EQUAL note, we may
- fold the comparison to always be false in a later CSE pass.
- (We could also delete the REG_NOTES when moving the insn, but it
- seems simpler to not move it.) An exception is that we can move
- the insn if the only note is a REG_EQUAL or REG_EQUIV whose
- value is the same as "a".
-
- INSN is the goto.
-
- We set:
-
- TEMP to the jump insn preceding "x = a;"
- TEMP1 to X
- TEMP2 to the insn that sets "x = b;"
- TEMP3 to the insn that sets "x = a;"
- TEMP4 to the set of "x = a"; */
-
- if (this_is_simplejump
- && (temp2 = next_active_insn (insn)) != 0
- && GET_CODE (temp2) == INSN
- && (temp4 = single_set (temp2)) != 0
- && GET_CODE (temp1 = SET_DEST (temp4)) == REG
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
- && (temp3 = prev_active_insn (insn)) != 0
- && GET_CODE (temp3) == INSN
- && (temp4 = single_set (temp3)) != 0
- && rtx_equal_p (SET_DEST (temp4), temp1)
- && ! side_effects_p (SET_SRC (temp4))
- && ! may_trap_p (SET_SRC (temp4))
- && (REG_NOTES (temp3) == 0
- || ((REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUAL
- || REG_NOTE_KIND (REG_NOTES (temp3)) == REG_EQUIV)
- && XEXP (REG_NOTES (temp3), 1) == 0
- && rtx_equal_p (XEXP (REG_NOTES (temp3), 0),
- SET_SRC (temp4))))
- && (temp = prev_active_insn (temp3)) != 0
- && condjump_p (temp) && ! simplejump_p (temp)
- /* TEMP must skip over the "x = a;" insn */
- && prev_real_insn (JUMP_LABEL (temp)) == insn
- && no_labels_between_p (temp, insn))
- {
- rtx prev_label = JUMP_LABEL (temp);
- rtx insert_after = prev_nonnote_insn (temp);
-
-#ifdef HAVE_cc0
- /* We cannot insert anything between a set of cc and its use. */
- if (insert_after && GET_RTX_CLASS (GET_CODE (insert_after)) == 'i'
- && sets_cc0_p (PATTERN (insert_after)))
- insert_after = prev_nonnote_insn (insert_after);
-#endif
- ++LABEL_NUSES (prev_label);
-
- if (insert_after
- && no_labels_between_p (insert_after, temp)
- && ! reg_referenced_between_p (temp1, insert_after, temp3)
- && ! reg_referenced_between_p (temp1, temp3,
- NEXT_INSN (temp2))
- && ! reg_set_between_p (temp1, insert_after, temp)
- && ! modified_between_p (SET_SRC (temp4), insert_after, temp)
- /* Verify that registers used by the jump are not clobbered
- by the instruction being moved. */
- && ! regs_set_between_p (PATTERN (temp),
- PREV_INSN (temp3),
- NEXT_INSN (temp3))
- && invert_jump (temp, JUMP_LABEL (insn)))
- {
- emit_insn_after_with_line_notes (PATTERN (temp3),
- insert_after, temp3);
- delete_insn (temp3);
- delete_insn (insn);
- /* Set NEXT to an insn that we know won't go away. */
- next = temp2;
- changed = 1;
- }
- if (prev_label && --LABEL_NUSES (prev_label) == 0)
- delete_insn (prev_label);
- if (changed)
- continue;
- }
-
-#if !defined(HAVE_cc0) && !defined(HAVE_conditional_arithmetic)
-
- /* If we have if (...) x = exp; and branches are expensive,
- EXP is a single insn, does not have any side effects, cannot
- trap, and is not too costly, convert this to
- t = exp; if (...) x = t;
-
- Don't do this when we have CC0 because it is unlikely to help
- and we'd need to worry about where to place the new insn and
- the potential for conflicts. We also can't do this when we have
- notes on the insn for the same reason as above.
-
- If we have conditional arithmetic, this will make this
- harder to optimize later and isn't needed, so don't do it
- in that case either.
-
- We set:
-
- TEMP to the "x = exp;" insn.
- TEMP1 to the single set in the "x = exp;" insn.
- TEMP2 to "x". */
-
- if (! reload_completed
- && this_is_condjump && ! this_is_simplejump
- && BRANCH_COST >= 3
- && (temp = next_nonnote_insn (insn)) != 0
- && GET_CODE (temp) == INSN
- && REG_NOTES (temp) == 0
- && (reallabelprev == temp
- || ((temp2 = next_active_insn (temp)) != 0
- && simplejump_p (temp2)
- && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
- && (temp1 = single_set (temp)) != 0
- && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
- && GET_CODE (SET_SRC (temp1)) != REG
- && GET_CODE (SET_SRC (temp1)) != SUBREG
- && GET_CODE (SET_SRC (temp1)) != CONST_INT
- && ! side_effects_p (SET_SRC (temp1))
- && ! may_trap_p (SET_SRC (temp1))
- && rtx_cost (SET_SRC (temp1), SET) < 10)
- {
- rtx new = gen_reg_rtx (GET_MODE (temp2));
-
- if ((temp3 = find_insert_position (insn, temp))
- && validate_change (temp, &SET_DEST (temp1), new, 0))
- {
- next = emit_insn_after (gen_move_insn (temp2, new), insn);
- emit_insn_after_with_line_notes (PATTERN (temp),
- PREV_INSN (temp3), temp);
- delete_insn (temp);
- reallabelprev = prev_active_insn (JUMP_LABEL (insn));
-
- if (after_regscan)
- {
- reg_scan_update (temp3, NEXT_INSN (next), old_max_reg);
- old_max_reg = max_reg_num ();
- }
- }
- }
-
- /* Similarly, if it takes two insns to compute EXP but they
- have the same destination. Here TEMP3 will be the second
- insn and TEMP4 the SET from that insn. */
-
- if (! reload_completed
- && this_is_condjump && ! this_is_simplejump
- && BRANCH_COST >= 4
- && (temp = next_nonnote_insn (insn)) != 0
- && GET_CODE (temp) == INSN
- && REG_NOTES (temp) == 0
- && (temp3 = next_nonnote_insn (temp)) != 0
- && GET_CODE (temp3) == INSN
- && REG_NOTES (temp3) == 0
- && (reallabelprev == temp3
- || ((temp2 = next_active_insn (temp3)) != 0
- && simplejump_p (temp2)
- && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
- && (temp1 = single_set (temp)) != 0
- && (temp2 = SET_DEST (temp1), GET_CODE (temp2) == REG)
- && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
- && ! side_effects_p (SET_SRC (temp1))
- && ! may_trap_p (SET_SRC (temp1))
- && rtx_cost (SET_SRC (temp1), SET) < 10
- && (temp4 = single_set (temp3)) != 0
- && rtx_equal_p (SET_DEST (temp4), temp2)
- && ! side_effects_p (SET_SRC (temp4))
- && ! may_trap_p (SET_SRC (temp4))
- && rtx_cost (SET_SRC (temp4), SET) < 10)
- {
- rtx new = gen_reg_rtx (GET_MODE (temp2));
-
- if ((temp5 = find_insert_position (insn, temp))
- && (temp6 = find_insert_position (insn, temp3))
- && validate_change (temp, &SET_DEST (temp1), new, 0))
- {
- /* Use the earliest of temp5 and temp6. */
- if (temp5 != insn)
- temp6 = temp5;
- next = emit_insn_after (gen_move_insn (temp2, new), insn);
- emit_insn_after_with_line_notes (PATTERN (temp),
- PREV_INSN (temp6), temp);
- emit_insn_after_with_line_notes
- (replace_rtx (PATTERN (temp3), temp2, new),
- PREV_INSN (temp6), temp3);
- delete_insn (temp);
- delete_insn (temp3);
- reallabelprev = prev_active_insn (JUMP_LABEL (insn));
-
- if (after_regscan)
- {
- reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
- old_max_reg = max_reg_num ();
- }
- }
- }
-
- /* Finally, handle the case where two insns are used to
- compute EXP but a temporary register is used. Here we must
- ensure that the temporary register is not used anywhere else. */
-
- if (! reload_completed
- && after_regscan
- && this_is_condjump && ! this_is_simplejump
- && BRANCH_COST >= 4
- && (temp = next_nonnote_insn (insn)) != 0
- && GET_CODE (temp) == INSN
- && REG_NOTES (temp) == 0
- && (temp3 = next_nonnote_insn (temp)) != 0
- && GET_CODE (temp3) == INSN
- && REG_NOTES (temp3) == 0
- && (reallabelprev == temp3
- || ((temp2 = next_active_insn (temp3)) != 0
- && simplejump_p (temp2)
- && JUMP_LABEL (temp2) == JUMP_LABEL (insn)))
- && (temp1 = single_set (temp)) != 0
- && (temp5 = SET_DEST (temp1),
- (GET_CODE (temp5) == REG
- || (GET_CODE (temp5) == SUBREG
- && (temp5 = SUBREG_REG (temp5),
- GET_CODE (temp5) == REG))))
- && REGNO (temp5) >= FIRST_PSEUDO_REGISTER
- && REGNO_FIRST_UID (REGNO (temp5)) == INSN_UID (temp)
- && REGNO_LAST_UID (REGNO (temp5)) == INSN_UID (temp3)
- && ! side_effects_p (SET_SRC (temp1))
- && ! may_trap_p (SET_SRC (temp1))
- && rtx_cost (SET_SRC (temp1), SET) < 10
- && (temp4 = single_set (temp3)) != 0
- && (temp2 = SET_DEST (temp4), GET_CODE (temp2) == REG)
- && GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp2) >= FIRST_PSEUDO_REGISTER)
- && rtx_equal_p (SET_DEST (temp4), temp2)
- && ! side_effects_p (SET_SRC (temp4))
- && ! may_trap_p (SET_SRC (temp4))
- && rtx_cost (SET_SRC (temp4), SET) < 10)
- {
- rtx new = gen_reg_rtx (GET_MODE (temp2));
-
- if ((temp5 = find_insert_position (insn, temp))
- && (temp6 = find_insert_position (insn, temp3))
- && validate_change (temp3, &SET_DEST (temp4), new, 0))
- {
- /* Use the earliest of temp5 and temp6. */
- if (temp5 != insn)
- temp6 = temp5;
- next = emit_insn_after (gen_move_insn (temp2, new), insn);
- emit_insn_after_with_line_notes (PATTERN (temp),
- PREV_INSN (temp6), temp);
- emit_insn_after_with_line_notes (PATTERN (temp3),
- PREV_INSN (temp6), temp3);
- delete_insn (temp);
- delete_insn (temp3);
- reallabelprev = prev_active_insn (JUMP_LABEL (insn));
-
- if (after_regscan)
- {
- reg_scan_update (temp6, NEXT_INSN (next), old_max_reg);
- old_max_reg = max_reg_num ();
- }
- }
- }
-#endif /* HAVE_cc0 */
-
-#ifdef HAVE_conditional_arithmetic
- /* ??? This is disabled in genconfig, as this simple-minded
- transformation can incredibly lengthen register lifetimes.
-
- Consider this example from cexp.c's yyparse:
-
- 234 (set (pc)
- (if_then_else (ne (reg:DI 149) (const_int 0 [0x0]))
- (label_ref 248) (pc)))
- 237 (set (reg/i:DI 0 $0) (const_int 1 [0x1]))
- 239 (set (pc) (label_ref 2382))
- 248 (code_label ("yybackup"))
-
- This will be transformed to:
-
- 237 (set (reg/i:DI 0 $0)
- (if_then_else:DI (eq (reg:DI 149) (const_int 0 [0x0]))
- (const_int 1 [0x1]) (reg/i:DI 0 $0)))
- 239 (set (pc)
- (if_then_else (eq (reg:DI 149) (const_int 0 [0x0]))
- (label_ref 2382) (pc)))
-
- which, from this narrow viewpoint looks fine. Except that
- between this and 3 other ocurrences of the same pattern, $0
- is now live for basically the entire function, and we'll
- get an abort in caller_save.
-
- Any replacement for this code should recall that a set of
- a register that is not live need not, and indeed should not,
- be conditionalized. Either that, or delay the transformation
- until after register allocation. */
-
- /* See if this is a conditional jump around a small number of
- instructions that we can conditionalize. Don't do this before
- the initial CSE pass or after reload.
-
- We reject any insns that have side effects or may trap.
- Strictly speaking, this is not needed since the machine may
- support conditionalizing these too, but we won't deal with that
- now. Specifically, this means that we can't conditionalize a
- CALL_INSN, which some machines, such as the ARC, can do, but
- this is a very minor optimization. */
- if (this_is_condjump && ! this_is_simplejump
- && cse_not_expected && ! reload_completed
- && BRANCH_COST > 2
- && can_reverse_comparison_p (XEXP (SET_SRC (PATTERN (insn)), 0),
- insn))
- {
- rtx ourcond = XEXP (SET_SRC (PATTERN (insn)), 0);
- int num_insns = 0;
- char *storage = (char *) oballoc (0);
- int last_insn = 0, failed = 0;
- rtx changed_jump = 0;
-
- ourcond = gen_rtx (reverse_condition (GET_CODE (ourcond)),
- VOIDmode, XEXP (ourcond, 0),
- XEXP (ourcond, 1));
-
- /* Scan forward BRANCH_COST real insns looking for the JUMP_LABEL
- of this insn. We see if we think we can conditionalize the
- insns we pass. For now, we only deal with insns that have
- one SET. We stop after an insn that modifies anything in
- OURCOND, if we have too many insns, or if we have an insn
- with a side effect or that may trip. Note that we will
- be modifying any unconditional jumps we encounter to be
- conditional; this will have the effect of also doing this
- optimization on the "else" the next time around. */
- for (temp1 = NEXT_INSN (insn);
- num_insns <= BRANCH_COST && ! failed && temp1 != 0
- && GET_CODE (temp1) != CODE_LABEL;
- temp1 = NEXT_INSN (temp1))
- {
- /* Ignore everything but an active insn. */
- if (GET_RTX_CLASS (GET_CODE (temp1)) != 'i'
- || GET_CODE (PATTERN (temp1)) == USE
- || GET_CODE (PATTERN (temp1)) == CLOBBER)
- continue;
-
- /* If this was an unconditional jump, record it since we'll
- need to remove the BARRIER if we succeed. We can only
- have one such jump since there must be a label after
- the BARRIER and it's either ours, in which case it's the
- only one or some other, in which case we'd fail.
- Likewise if it's a CALL_INSN followed by a BARRIER. */
-
- if (simplejump_p (temp1)
- || (GET_CODE (temp1) == CALL_INSN
- && NEXT_INSN (temp1) != 0
- && GET_CODE (NEXT_INSN (temp1)) == BARRIER))
- {
- if (changed_jump == 0)
- changed_jump = temp1;
- else
- changed_jump
- = gen_rtx_INSN_LIST (VOIDmode, temp1, changed_jump);
- }
-
- /* See if we are allowed another insn and if this insn
- if one we think we may be able to handle. */
- if (++num_insns > BRANCH_COST
- || last_insn
- || (((temp2 = single_set (temp1)) == 0
- || side_effects_p (SET_SRC (temp2))
- || may_trap_p (SET_SRC (temp2)))
- && GET_CODE (temp1) != CALL_INSN))
- failed = 1;
- else if (temp2 != 0)
- validate_change (temp1, &SET_SRC (temp2),
- gen_rtx_IF_THEN_ELSE
- (GET_MODE (SET_DEST (temp2)),
- copy_rtx (ourcond),
- SET_SRC (temp2), SET_DEST (temp2)),
- 1);
- else
- {
- /* This is a CALL_INSN that doesn't have a SET. */
- rtx *call_loc = &PATTERN (temp1);
-
- if (GET_CODE (*call_loc) == PARALLEL)
- call_loc = &XVECEXP (*call_loc, 0, 0);
-
- validate_change (temp1, call_loc,
- gen_rtx_IF_THEN_ELSE
- (VOIDmode, copy_rtx (ourcond),
- *call_loc, const0_rtx),
- 1);
- }
-
-
- if (modified_in_p (ourcond, temp1))
- last_insn = 1;
- }
-
- /* If we've reached our jump label, haven't failed, and all
- the changes above are valid, we can delete this jump
- insn. Also remove a BARRIER after any jump that used
- to be unconditional and remove any REG_EQUAL or REG_EQUIV
- that might have previously been present on insns we
- made conditional. */
- if (temp1 == JUMP_LABEL (insn) && ! failed
- && apply_change_group ())
- {
- for (temp1 = NEXT_INSN (insn); temp1 != JUMP_LABEL (insn);
- temp1 = NEXT_INSN (temp1))
- if (GET_RTX_CLASS (GET_CODE (temp1)) == 'i')
- for (temp2 = REG_NOTES (temp1); temp2 != 0;
- temp2 = XEXP (temp2, 1))
- if (REG_NOTE_KIND (temp2) == REG_EQUAL
- || REG_NOTE_KIND (temp2) == REG_EQUIV)
- remove_note (temp1, temp2);
-
- if (changed_jump != 0)
- {
- while (GET_CODE (changed_jump) == INSN_LIST)
- {
- delete_barrier (NEXT_INSN (XEXP (changed_jump, 0)));
- changed_jump = XEXP (changed_jump, 1);
- }
-
- delete_barrier (NEXT_INSN (changed_jump));
- }
-
- delete_insn (insn);
- changed = 1;
- continue;
- }
- else
- {
- cancel_changes (0);
- obfree (storage);
- }
- }
-#endif
- /* If branches are expensive, convert
- if (foo) bar++; to bar += (foo != 0);
- and similarly for "bar--;"
-
- INSN is the conditional branch around the arithmetic. We set:
-
- TEMP is the arithmetic insn.
- TEMP1 is the SET doing the arithmetic.
- TEMP2 is the operand being incremented or decremented.
- TEMP3 to the condition being tested.
- TEMP4 to the earliest insn used to find the condition. */
-
- if ((BRANCH_COST >= 2
-#ifdef HAVE_incscc
- || HAVE_incscc
-#endif
-#ifdef HAVE_decscc
- || HAVE_decscc
-#endif
- )
- && ! reload_completed
- && this_is_condjump && ! this_is_simplejump
- && (temp = next_nonnote_insn (insn)) != 0
- && (temp1 = single_set (temp)) != 0
- && (temp2 = SET_DEST (temp1),
- GET_MODE_CLASS (GET_MODE (temp2)) == MODE_INT)
- && GET_CODE (SET_SRC (temp1)) == PLUS
- && (XEXP (SET_SRC (temp1), 1) == const1_rtx
- || XEXP (SET_SRC (temp1), 1) == constm1_rtx)
- && rtx_equal_p (temp2, XEXP (SET_SRC (temp1), 0))
- && ! side_effects_p (temp2)
- && ! may_trap_p (temp2)
- /* INSN must either branch to the insn after TEMP or the insn
- after TEMP must branch to the same place as INSN. */
- && (reallabelprev == temp
- || ((temp3 = next_active_insn (temp)) != 0
- && simplejump_p (temp3)
- && JUMP_LABEL (temp3) == JUMP_LABEL (insn)))
- && (temp3 = get_condition (insn, &temp4)) != 0
- /* We must be comparing objects whose modes imply the size.
- We could handle BLKmode if (1) emit_store_flag could
- and (2) we could find the size reliably. */
- && GET_MODE (XEXP (temp3, 0)) != BLKmode
- && can_reverse_comparison_p (temp3, insn))
- {
- rtx temp6, target = 0, seq, init_insn = 0, init = temp2;
- enum rtx_code code = reverse_condition (GET_CODE (temp3));
-
- start_sequence ();
-
- /* It must be the case that TEMP2 is not modified in the range
- [TEMP4, INSN). The one exception we make is if the insn
- before INSN sets TEMP2 to something which is also unchanged
- in that range. In that case, we can move the initialization
- into our sequence. */
-
- if ((temp5 = prev_active_insn (insn)) != 0
- && no_labels_between_p (temp5, insn)
- && GET_CODE (temp5) == INSN
- && (temp6 = single_set (temp5)) != 0
- && rtx_equal_p (temp2, SET_DEST (temp6))
- && (CONSTANT_P (SET_SRC (temp6))
- || GET_CODE (SET_SRC (temp6)) == REG
- || GET_CODE (SET_SRC (temp6)) == SUBREG))
- {
- emit_insn (PATTERN (temp5));
- init_insn = temp5;
- init = SET_SRC (temp6);
- }
-
- if (CONSTANT_P (init)
- || ! reg_set_between_p (init, PREV_INSN (temp4), insn))
- target = emit_store_flag (gen_reg_rtx (GET_MODE (temp2)), code,
- XEXP (temp3, 0), XEXP (temp3, 1),
- VOIDmode,
- (code == LTU || code == LEU
- || code == GTU || code == GEU), 1);
-
- /* If we can do the store-flag, do the addition or
- subtraction. */
-
- if (target)
- target = expand_binop (GET_MODE (temp2),
- (XEXP (SET_SRC (temp1), 1) == const1_rtx
- ? add_optab : sub_optab),
- temp2, target, temp2, 0, OPTAB_WIDEN);
-
- if (target != 0)
- {
- /* Put the result back in temp2 in case it isn't already.
- Then replace the jump, possible a CC0-setting insn in
- front of the jump, and TEMP, with the sequence we have
- made. */
-
- if (target != temp2)
- emit_move_insn (temp2, target);
-
- seq = get_insns ();
- end_sequence ();
-
- emit_insns_before (seq, temp4);
- delete_insn (temp);
-
- if (init_insn)
- delete_insn (init_insn);
-
- next = NEXT_INSN (insn);
-#ifdef HAVE_cc0
- delete_insn (prev_nonnote_insn (insn));
-#endif
- delete_insn (insn);
-
- if (after_regscan)
- {
- reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
- old_max_reg = max_reg_num ();
- }
-
- changed = 1;
- continue;
- }
- else
- end_sequence ();
- }
-
- /* Try to use a conditional move (if the target has them), or a
- store-flag insn. If the target has conditional arithmetic as
- well as conditional move, the above code will have done something.
- Note that we prefer the above code since it is more general: the
- code below can make changes that require work to undo.
-
- The general case here is:
-
- 1) x = a; if (...) x = b; and
- 2) if (...) x = b;
-
- If the jump would be faster, the machine should not have defined
- the movcc or scc insns!. These cases are often made by the
- previous optimization.
-
- The second case is treated as x = x; if (...) x = b;.
-
- INSN here is the jump around the store. We set:
-
- TEMP to the "x op= b;" insn.
- TEMP1 to X.
- TEMP2 to B.
- TEMP3 to A (X in the second case).
- TEMP4 to the condition being tested.
- TEMP5 to the earliest insn used to find the condition.
- TEMP6 to the SET of TEMP. */
-
- if (/* We can't do this after reload has completed. */
- ! reload_completed
-#ifdef HAVE_conditional_arithmetic
- /* Defer this until after CSE so the above code gets the
- first crack at it. */
- && cse_not_expected
-#endif
- && this_is_condjump && ! this_is_simplejump
- /* Set TEMP to the "x = b;" insn. */
- && (temp = next_nonnote_insn (insn)) != 0
- && GET_CODE (temp) == INSN
- && (temp6 = single_set (temp)) != NULL_RTX
- && GET_CODE (temp1 = SET_DEST (temp6)) == REG
- && (! SMALL_REGISTER_CLASSES
- || REGNO (temp1) >= FIRST_PSEUDO_REGISTER)
- && ! side_effects_p (temp2 = SET_SRC (temp6))
- && ! may_trap_p (temp2)
- /* Allow either form, but prefer the former if both apply.
- There is no point in using the old value of TEMP1 if
- it is a register, since cse will alias them. It can
- lose if the old value were a hard register since CSE
- won't replace hard registers. Avoid using TEMP3 if
- small register classes and it is a hard register. */
- && (((temp3 = reg_set_last (temp1, insn)) != 0
- && ! (SMALL_REGISTER_CLASSES && GET_CODE (temp3) == REG
- && REGNO (temp3) < FIRST_PSEUDO_REGISTER))
- /* Make the latter case look like x = x; if (...) x = b; */
- || (temp3 = temp1, 1))
- /* INSN must either branch to the insn after TEMP or the insn
- after TEMP must branch to the same place as INSN. */
- && (reallabelprev == temp
- || ((temp4 = next_active_insn (temp)) != 0
- && simplejump_p (temp4)
- && JUMP_LABEL (temp4) == JUMP_LABEL (insn)))
- && (temp4 = get_condition (insn, &temp5)) != 0
- /* We must be comparing objects whose modes imply the size.
- We could handle BLKmode if (1) emit_store_flag could
- and (2) we could find the size reliably. */
- && GET_MODE (XEXP (temp4, 0)) != BLKmode
- /* Even if branches are cheap, the store_flag optimization
- can win when the operation to be performed can be
- expressed directly. */
-#ifdef HAVE_cc0
- /* If the previous insn sets CC0 and something else, we can't
- do this since we are going to delete that insn. */
-
- && ! ((temp6 = prev_nonnote_insn (insn)) != 0
- && GET_CODE (temp6) == INSN
- && (sets_cc0_p (PATTERN (temp6)) == -1
- || (sets_cc0_p (PATTERN (temp6)) == 1
- && FIND_REG_INC_NOTE (temp6, NULL_RTX))))
-#endif
- )
- {
-#ifdef HAVE_conditional_move
- /* First try a conditional move. */
- {
- enum rtx_code code = GET_CODE (temp4);
- rtx var = temp1;
- rtx cond0, cond1, aval, bval;
- rtx target, new_insn;
-
- /* Copy the compared variables into cond0 and cond1, so that
- any side effects performed in or after the old comparison,
- will not affect our compare which will come later. */
- /* ??? Is it possible to just use the comparison in the jump
- insn? After all, we're going to delete it. We'd have
- to modify emit_conditional_move to take a comparison rtx
- instead or write a new function. */
-
- /* We want the target to be able to simplify comparisons with
- zero (and maybe other constants as well), so don't create
- pseudos for them. There's no need to either. */
- if (GET_CODE (XEXP (temp4, 0)) == CONST_INT
- || GET_CODE (XEXP (temp4, 0)) == CONST_DOUBLE)
- cond0 = XEXP (temp4, 0);
- else
- cond0 = gen_reg_rtx (GET_MODE (XEXP (temp4, 0)));
-
- if (GET_CODE (XEXP (temp4, 1)) == CONST_INT
- || GET_CODE (XEXP (temp4, 1)) == CONST_DOUBLE)
- cond1 = XEXP (temp4, 1);
- else
- cond1 = gen_reg_rtx (GET_MODE (XEXP (temp4, 1)));
-
- /* Careful about copying these values -- an IOR or what may
- need to do other things, like clobber flags. */
- /* ??? Assume for the moment that AVAL is ok. */
- aval = temp3;
-
- start_sequence ();
-
- /* We're dealing with a single_set insn with no side effects
- on SET_SRC. We do need to be reasonably certain that if
- we need to force BVAL into a register that we won't
- clobber the flags -- general_operand should suffice. */
- if (general_operand (temp2, GET_MODE (var)))
- bval = temp2;
- else
- {
- bval = gen_reg_rtx (GET_MODE (var));
- new_insn = copy_rtx (temp);
- temp6 = single_set (new_insn);
- SET_DEST (temp6) = bval;
- emit_insn (PATTERN (new_insn));
- }
-
- target = emit_conditional_move (var, code,
- cond0, cond1, VOIDmode,
- aval, bval, GET_MODE (var),
- (code == LTU || code == GEU
- || code == LEU || code == GTU));
-
- if (target)
- {
- rtx seq1, seq2, last;
- int copy_ok;
-
- /* Save the conditional move sequence but don't emit it
- yet. On some machines, like the alpha, it is possible
- that temp5 == insn, so next generate the sequence that
- saves the compared values and then emit both
- sequences ensuring seq1 occurs before seq2. */
- seq2 = get_insns ();
- end_sequence ();
-
- /* "Now that we can't fail..." Famous last words.
- Generate the copy insns that preserve the compared
- values. */
- start_sequence ();
- emit_move_insn (cond0, XEXP (temp4, 0));
- if (cond1 != XEXP (temp4, 1))
- emit_move_insn (cond1, XEXP (temp4, 1));
- seq1 = get_insns ();
- end_sequence ();
-
- /* Validate the sequence -- this may be some weird
- bit-extract-and-test instruction for which there
- exists no complimentary bit-extract insn. */
- copy_ok = 1;
- for (last = seq1; last ; last = NEXT_INSN (last))
- if (recog_memoized (last) < 0)
- {
- copy_ok = 0;
- break;
- }
-
- if (copy_ok)
- {
- emit_insns_before (seq1, temp5);
-
- /* Insert conditional move after insn, to be sure
- that the jump and a possible compare won't be
- separated. */
- last = emit_insns_after (seq2, insn);
-
- /* ??? We can also delete the insn that sets X to A.
- Flow will do it too though. */
- delete_insn (temp);
- next = NEXT_INSN (insn);
- delete_jump (insn);
-
- if (after_regscan)
- {
- reg_scan_update (seq1, NEXT_INSN (last),
- old_max_reg);
- old_max_reg = max_reg_num ();
- }
-
- changed = 1;
- continue;
- }
- }
- else
- end_sequence ();
- }
-#endif
-
- /* That didn't work, try a store-flag insn.
-
- We further divide the cases into:
-
- 1) x = a; if (...) x = b; and either A or B is zero,
- 2) if (...) x = 0; and jumps are expensive,
- 3) x = a; if (...) x = b; and A and B are constants where all
- the set bits in A are also set in B and jumps are expensive,
- 4) x = a; if (...) x = b; and A and B non-zero, and jumps are
- more expensive, and
- 5) if (...) x = b; if jumps are even more expensive. */
-
- if (GET_MODE_CLASS (GET_MODE (temp1)) == MODE_INT
- /* We will be passing this as operand into expand_and. No
- good if it's not valid as an operand. */
- && general_operand (temp2, GET_MODE (temp2))
- && ((GET_CODE (temp3) == CONST_INT)
- /* Make the latter case look like
- x = x; if (...) x = 0; */
- || (temp3 = temp1,
- ((BRANCH_COST >= 2
- && temp2 == const0_rtx)
- || BRANCH_COST >= 3)))
- /* If B is zero, OK; if A is zero, can only do (1) if we
- can reverse the condition. See if (3) applies possibly
- by reversing the condition. Prefer reversing to (4) when
- branches are very expensive. */
- && (((BRANCH_COST >= 2
- || STORE_FLAG_VALUE == -1
- || (STORE_FLAG_VALUE == 1
- /* Check that the mask is a power of two,
- so that it can probably be generated
- with a shift. */
- && GET_CODE (temp3) == CONST_INT
- && exact_log2 (INTVAL (temp3)) >= 0))
- && (reversep = 0, temp2 == const0_rtx))
- || ((BRANCH_COST >= 2
- || STORE_FLAG_VALUE == -1
- || (STORE_FLAG_VALUE == 1
- && GET_CODE (temp2) == CONST_INT
- && exact_log2 (INTVAL (temp2)) >= 0))
- && temp3 == const0_rtx
- && (reversep = can_reverse_comparison_p (temp4, insn)))
- || (BRANCH_COST >= 2
- && GET_CODE (temp2) == CONST_INT
- && GET_CODE (temp3) == CONST_INT
- && ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp2)
- || ((INTVAL (temp2) & INTVAL (temp3)) == INTVAL (temp3)
- && (reversep = can_reverse_comparison_p (temp4,
- insn)))))
- || BRANCH_COST >= 3)
- )
- {
- enum rtx_code code = GET_CODE (temp4);
- rtx uval, cval, var = temp1;
- int normalizep;
- rtx target;
-
- /* If necessary, reverse the condition. */
- if (reversep)
- code = reverse_condition (code), uval = temp2, cval = temp3;
- else
- uval = temp3, cval = temp2;
-
- /* If CVAL is non-zero, normalize to -1. Otherwise, if UVAL
- is the constant 1, it is best to just compute the result
- directly. If UVAL is constant and STORE_FLAG_VALUE
- includes all of its bits, it is best to compute the flag
- value unnormalized and `and' it with UVAL. Otherwise,
- normalize to -1 and `and' with UVAL. */
- normalizep = (cval != const0_rtx ? -1
- : (uval == const1_rtx ? 1
- : (GET_CODE (uval) == CONST_INT
- && (INTVAL (uval) & ~STORE_FLAG_VALUE) == 0)
- ? 0 : -1));
-
- /* We will be putting the store-flag insn immediately in
- front of the comparison that was originally being done,
- so we know all the variables in TEMP4 will be valid.
- However, this might be in front of the assignment of
- A to VAR. If it is, it would clobber the store-flag
- we will be emitting.
-
- Therefore, emit into a temporary which will be copied to
- VAR immediately after TEMP. */
-
- start_sequence ();
- target = emit_store_flag (gen_reg_rtx (GET_MODE (var)), code,
- XEXP (temp4, 0), XEXP (temp4, 1),
- VOIDmode,
- (code == LTU || code == LEU
- || code == GEU || code == GTU),
- normalizep);
- if (target)
- {
- rtx seq;
- rtx before = insn;
-
- seq = get_insns ();
- end_sequence ();
-
- /* Put the store-flag insns in front of the first insn
- used to compute the condition to ensure that we
- use the same values of them as the current
- comparison. However, the remainder of the insns we
- generate will be placed directly in front of the
- jump insn, in case any of the pseudos we use
- are modified earlier. */
-
- emit_insns_before (seq, temp5);
-
- start_sequence ();
-
- /* Both CVAL and UVAL are non-zero. */
- if (cval != const0_rtx && uval != const0_rtx)
- {
- rtx tem1, tem2;
-
- tem1 = expand_and (uval, target, NULL_RTX);
- if (GET_CODE (cval) == CONST_INT
- && GET_CODE (uval) == CONST_INT
- && (INTVAL (cval) & INTVAL (uval)) == INTVAL (cval))
- tem2 = cval;
- else
- {
- tem2 = expand_unop (GET_MODE (var), one_cmpl_optab,
- target, NULL_RTX, 0);
- tem2 = expand_and (cval, tem2,
- (GET_CODE (tem2) == REG
- ? tem2 : 0));
- }
-
- /* If we usually make new pseudos, do so here. This
- turns out to help machines that have conditional
- move insns. */
- /* ??? Conditional moves have already been handled.
- This may be obsolete. */
-
- if (flag_expensive_optimizations)
- target = 0;
-
- target = expand_binop (GET_MODE (var), ior_optab,
- tem1, tem2, target,
- 1, OPTAB_WIDEN);
- }
- else if (normalizep != 1)
- {
- /* We know that either CVAL or UVAL is zero. If
- UVAL is zero, negate TARGET and `and' with CVAL.
- Otherwise, `and' with UVAL. */
- if (uval == const0_rtx)
- {
- target = expand_unop (GET_MODE (var), one_cmpl_optab,
- target, NULL_RTX, 0);
- uval = cval;
- }
-
- target = expand_and (uval, target,
- (GET_CODE (target) == REG
- && ! preserve_subexpressions_p ()
- ? target : NULL_RTX));
- }
-
- emit_move_insn (var, target);
- seq = get_insns ();
- end_sequence ();
-#ifdef HAVE_cc0
- /* If INSN uses CC0, we must not separate it from the
- insn that sets cc0. */
- if (reg_mentioned_p (cc0_rtx, PATTERN (before)))
- before = prev_nonnote_insn (before);
-#endif
- emit_insns_before (seq, before);
-
- delete_insn (temp);
- next = NEXT_INSN (insn);
- delete_jump (insn);
-
- if (after_regscan)
- {
- reg_scan_update (seq, NEXT_INSN (next), old_max_reg);
- old_max_reg = max_reg_num ();
- }
-
- changed = 1;
- continue;
- }
- else
- end_sequence ();
- }
- }
-
-
- /* Simplify if (...) x = 1; else {...} if (x) ...
- We recognize this case scanning backwards as well.
-
- TEMP is the assignment to x;
- TEMP1 is the label at the head of the second if. */
- /* ?? This should call get_condition to find the values being
- compared, instead of looking for a COMPARE insn when HAVE_cc0
- is not defined. This would allow it to work on the m88k. */
- /* ?? This optimization is only safe before cse is run if HAVE_cc0
- is not defined and the condition is tested by a separate compare
- insn. This is because the code below assumes that the result
- of the compare dies in the following branch.
-
- Not only that, but there might be other insns between the
- compare and branch whose results are live. Those insns need
- to be executed.
-
- A way to fix this is to move the insns at JUMP_LABEL (insn)
- to before INSN. If we are running before flow, they will
- be deleted if they aren't needed. But this doesn't work
- well after flow.
-
- This is really a special-case of jump threading, anyway. The
- right thing to do is to replace this and jump threading with
- much simpler code in cse.
-
- This code has been turned off in the non-cc0 case in the
- meantime. */
-
-#ifdef HAVE_cc0
- else if (this_is_simplejump
- /* Safe to skip USE and CLOBBER insns here
- since they will not be deleted. */
- && (temp = prev_active_insn (insn))
- && no_labels_between_p (temp, insn)
- && GET_CODE (temp) == INSN
- && GET_CODE (PATTERN (temp)) == SET
- && GET_CODE (SET_DEST (PATTERN (temp))) == REG
- && CONSTANT_P (SET_SRC (PATTERN (temp)))
- && (temp1 = next_active_insn (JUMP_LABEL (insn)))
- /* If we find that the next value tested is `x'
- (TEMP1 is the insn where this happens), win. */
- && GET_CODE (temp1) == INSN
- && GET_CODE (PATTERN (temp1)) == SET
-#ifdef HAVE_cc0
- /* Does temp1 `tst' the value of x? */
- && SET_SRC (PATTERN (temp1)) == SET_DEST (PATTERN (temp))
- && SET_DEST (PATTERN (temp1)) == cc0_rtx
- && (temp1 = next_nonnote_insn (temp1))
-#else
- /* Does temp1 compare the value of x against zero? */
- && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
- && XEXP (SET_SRC (PATTERN (temp1)), 1) == const0_rtx
- && (XEXP (SET_SRC (PATTERN (temp1)), 0)
- == SET_DEST (PATTERN (temp)))
- && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
- && (temp1 = find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
-#endif
- && condjump_p (temp1))
- {
- /* Get the if_then_else from the condjump. */
- rtx choice = SET_SRC (PATTERN (temp1));
- if (GET_CODE (choice) == IF_THEN_ELSE)
- {
- enum rtx_code code = GET_CODE (XEXP (choice, 0));
- rtx val = SET_SRC (PATTERN (temp));
- rtx cond
- = simplify_relational_operation (code, GET_MODE (SET_DEST (PATTERN (temp))),
- val, const0_rtx);
- rtx ultimate;
-
- if (cond == const_true_rtx)
- ultimate = XEXP (choice, 1);
- else if (cond == const0_rtx)
- ultimate = XEXP (choice, 2);
- else
- ultimate = 0;
-
- if (ultimate == pc_rtx)
- ultimate = get_label_after (temp1);
- else if (ultimate && GET_CODE (ultimate) != RETURN)
- ultimate = XEXP (ultimate, 0);
-
- if (ultimate && JUMP_LABEL(insn) != ultimate)
- changed |= redirect_jump (insn, ultimate);
- }
- }
-#endif
-
-#if 0
- /* @@ This needs a bit of work before it will be right.
-
- Any type of comparison can be accepted for the first and
- second compare. When rewriting the first jump, we must
- compute the what conditions can reach label3, and use the
- appropriate code. We can not simply reverse/swap the code
- of the first jump. In some cases, the second jump must be
- rewritten also.
-
- For example,
- < == converts to > ==
- < != converts to == >
- etc.
-
- If the code is written to only accept an '==' test for the second
- compare, then all that needs to be done is to swap the condition
- of the first branch.
-
- It is questionable whether we want this optimization anyways,
- since if the user wrote code like this because he/she knew that
- the jump to label1 is taken most of the time, then rewriting
- this gives slower code. */
- /* @@ This should call get_condition to find the values being
- compared, instead of looking for a COMPARE insn when HAVE_cc0
- is not defined. This would allow it to work on the m88k. */
- /* @@ This optimization is only safe before cse is run if HAVE_cc0
- is not defined and the condition is tested by a separate compare
- insn. This is because the code below assumes that the result
- of the compare dies in the following branch. */
-
- /* Simplify test a ~= b
- condjump label1;
- test a == b
- condjump label2;
- jump label3;
- label1:
-
- rewriting as
- test a ~~= b
- condjump label3
- test a == b
- condjump label2
- label1:
-
- where ~= is an inequality, e.g. >, and ~~= is the swapped
- inequality, e.g. <.
-
- We recognize this case scanning backwards.
-
- TEMP is the conditional jump to `label2';
- TEMP1 is the test for `a == b';
- TEMP2 is the conditional jump to `label1';
- TEMP3 is the test for `a ~= b'. */
- else if (this_is_simplejump
- && (temp = prev_active_insn (insn))
- && no_labels_between_p (temp, insn)
- && condjump_p (temp)
- && (temp1 = prev_active_insn (temp))
- && no_labels_between_p (temp1, temp)
- && GET_CODE (temp1) == INSN
- && GET_CODE (PATTERN (temp1)) == SET
-#ifdef HAVE_cc0
- && sets_cc0_p (PATTERN (temp1)) == 1
-#else
- && GET_CODE (SET_SRC (PATTERN (temp1))) == COMPARE
- && GET_CODE (SET_DEST (PATTERN (temp1))) == REG
- && (temp == find_next_ref (SET_DEST (PATTERN (temp1)), temp1))
-#endif
- && (temp2 = prev_active_insn (temp1))
- && no_labels_between_p (temp2, temp1)
- && condjump_p (temp2)
- && JUMP_LABEL (temp2) == next_nonnote_insn (NEXT_INSN (insn))
- && (temp3 = prev_active_insn (temp2))
- && no_labels_between_p (temp3, temp2)
- && GET_CODE (PATTERN (temp3)) == SET
- && rtx_equal_p (SET_DEST (PATTERN (temp3)),
- SET_DEST (PATTERN (temp1)))
- && rtx_equal_p (SET_SRC (PATTERN (temp1)),
- SET_SRC (PATTERN (temp3)))
- && ! inequality_comparisons_p (PATTERN (temp))
- && inequality_comparisons_p (PATTERN (temp2)))
- {
- rtx fallthrough_label = JUMP_LABEL (temp2);
-
- ++LABEL_NUSES (fallthrough_label);
- if (swap_jump (temp2, JUMP_LABEL (insn)))
- {
- delete_insn (insn);
- changed = 1;
- }
-
- if (--LABEL_NUSES (fallthrough_label) == 0)
- delete_insn (fallthrough_label);
- }
-#endif
- /* Simplify if (...) {... x = 1;} if (x) ...
-
- We recognize this case backwards.
-
- TEMP is the test of `x';
- TEMP1 is the assignment to `x' at the end of the
- previous statement. */
- /* @@ This should call get_condition to find the values being
- compared, instead of looking for a COMPARE insn when HAVE_cc0
- is not defined. This would allow it to work on the m88k. */
- /* @@ This optimization is only safe before cse is run if HAVE_cc0
- is not defined and the condition is tested by a separate compare
- insn. This is because the code below assumes that the result
- of the compare dies in the following branch. */
-
- /* ??? This has to be turned off. The problem is that the
- unconditional jump might indirectly end up branching to the
- label between TEMP1 and TEMP. We can't detect this, in general,
- since it may become a jump to there after further optimizations.
- If that jump is done, it will be deleted, so we will retry
- this optimization in the next pass, thus an infinite loop.
-
- The present code prevents this by putting the jump after the
- label, but this is not logically correct. */
-#if 0
- else if (this_is_condjump
- /* Safe to skip USE and CLOBBER insns here
- since they will not be deleted. */
- && (temp = prev_active_insn (insn))
- && no_labels_between_p (temp, insn)
- && GET_CODE (temp) == INSN
- && GET_CODE (PATTERN (temp)) == SET
-#ifdef HAVE_cc0
- && sets_cc0_p (PATTERN (temp)) == 1
- && GET_CODE (SET_SRC (PATTERN (temp))) == REG
-#else
- /* Temp must be a compare insn, we can not accept a register
- to register move here, since it may not be simply a
- tst insn. */
- && GET_CODE (SET_SRC (PATTERN (temp))) == COMPARE
- && XEXP (SET_SRC (PATTERN (temp)), 1) == const0_rtx
- && GET_CODE (XEXP (SET_SRC (PATTERN (temp)), 0)) == REG
- && GET_CODE (SET_DEST (PATTERN (temp))) == REG
- && insn == find_next_ref (SET_DEST (PATTERN (temp)), temp)
-#endif
- /* May skip USE or CLOBBER insns here
- for checking for opportunity, since we
- take care of them later. */
- && (temp1 = prev_active_insn (temp))
- && GET_CODE (temp1) == INSN
- && GET_CODE (PATTERN (temp1)) == SET
-#ifdef HAVE_cc0
- && SET_SRC (PATTERN (temp)) == SET_DEST (PATTERN (temp1))
-#else
- && (XEXP (SET_SRC (PATTERN (temp)), 0)
- == SET_DEST (PATTERN (temp1)))
-#endif
- && CONSTANT_P (SET_SRC (PATTERN (temp1)))
- /* If this isn't true, cse will do the job. */
- && ! no_labels_between_p (temp1, temp))
- {
- /* Get the if_then_else from the condjump. */
- rtx choice = SET_SRC (PATTERN (insn));
- if (GET_CODE (choice) == IF_THEN_ELSE
- && (GET_CODE (XEXP (choice, 0)) == EQ
- || GET_CODE (XEXP (choice, 0)) == NE))
- {
- int want_nonzero = (GET_CODE (XEXP (choice, 0)) == NE);
- rtx last_insn;
- rtx ultimate;
- rtx p;
-
- /* Get the place that condjump will jump to
- if it is reached from here. */
- if ((SET_SRC (PATTERN (temp1)) != const0_rtx)
- == want_nonzero)
- ultimate = XEXP (choice, 1);
- else
- ultimate = XEXP (choice, 2);
- /* Get it as a CODE_LABEL. */
- if (ultimate == pc_rtx)
- ultimate = get_label_after (insn);
- else
- /* Get the label out of the LABEL_REF. */
- ultimate = XEXP (ultimate, 0);
-
- /* Insert the jump immediately before TEMP, specifically
- after the label that is between TEMP1 and TEMP. */
- last_insn = PREV_INSN (temp);
-
- /* If we would be branching to the next insn, the jump
- would immediately be deleted and the re-inserted in
- a subsequent pass over the code. So don't do anything
- in that case. */
- if (next_active_insn (last_insn)
- != next_active_insn (ultimate))
- {
- emit_barrier_after (last_insn);
- p = emit_jump_insn_after (gen_jump (ultimate),
- last_insn);
- JUMP_LABEL (p) = ultimate;
- ++LABEL_NUSES (ultimate);
- if (INSN_UID (ultimate) < max_jump_chain
- && INSN_CODE (p) < max_jump_chain)
- {
- jump_chain[INSN_UID (p)]
- = jump_chain[INSN_UID (ultimate)];
- jump_chain[INSN_UID (ultimate)] = p;
- }
- changed = 1;
- continue;
- }
- }
- }
-#endif
-#ifdef HAVE_trap
- /* Detect a conditional jump jumping over an unconditional trap. */
- else if (HAVE_trap
- && this_is_condjump && ! this_is_simplejump
- && reallabelprev != 0
- && GET_CODE (reallabelprev) == INSN
- && GET_CODE (PATTERN (reallabelprev)) == TRAP_IF
- && TRAP_CONDITION (PATTERN (reallabelprev)) == const_true_rtx
- && prev_active_insn (reallabelprev) == insn
- && no_labels_between_p (insn, reallabelprev)
- && (temp2 = get_condition (insn, &temp4))
- && can_reverse_comparison_p (temp2, insn))
- {
- rtx new = gen_cond_trap (reverse_condition (GET_CODE (temp2)),
- XEXP (temp2, 0), XEXP (temp2, 1),
- TRAP_CODE (PATTERN (reallabelprev)));
-
- if (new)
- {
- emit_insn_before (new, temp4);
- delete_insn (reallabelprev);
- delete_jump (insn);
- changed = 1;
- continue;
- }
- }
- /* Detect a jump jumping to an unconditional trap. */
- else if (HAVE_trap && this_is_condjump
- && (temp = next_active_insn (JUMP_LABEL (insn)))
- && GET_CODE (temp) == INSN
- && GET_CODE (PATTERN (temp)) == TRAP_IF
- && (this_is_simplejump
- || (temp2 = get_condition (insn, &temp4))))
- {
- rtx tc = TRAP_CONDITION (PATTERN (temp));
-
- if (tc == const_true_rtx
- || (! this_is_simplejump && rtx_equal_p (temp2, tc)))
- {
- rtx new;
- /* Replace an unconditional jump to a trap with a trap. */
- if (this_is_simplejump)
- {
- emit_barrier_after (emit_insn_before (gen_trap (), insn));
- delete_jump (insn);
- changed = 1;
- continue;
- }
- new = gen_cond_trap (GET_CODE (temp2), XEXP (temp2, 0),
- XEXP (temp2, 1),
- TRAP_CODE (PATTERN (temp)));
- if (new)
- {
- emit_insn_before (new, temp4);
- delete_jump (insn);
- changed = 1;
- continue;
- }
- }
- /* If the trap condition and jump condition are mutually
- exclusive, redirect the jump to the following insn. */
- else if (GET_RTX_CLASS (GET_CODE (tc)) == '<'
- && ! this_is_simplejump
- && swap_condition (GET_CODE (temp2)) == GET_CODE (tc)
- && rtx_equal_p (XEXP (tc, 0), XEXP (temp2, 0))
- && rtx_equal_p (XEXP (tc, 1), XEXP (temp2, 1))
- && redirect_jump (insn, get_label_after (temp)))
- {
- changed = 1;
- continue;
- }
- }
-#endif
- else
- {
- /* Now that the jump has been tensioned,
- try cross jumping: check for identical code
- before the jump and before its target label. */
-
- /* First, cross jumping of conditional jumps: */
-
- if (cross_jump && condjump_p (insn))
- {
- rtx newjpos, newlpos;
- rtx x = prev_real_insn (JUMP_LABEL (insn));
-
- /* A conditional jump may be crossjumped
- only if the place it jumps to follows
- an opposing jump that comes back here. */
-
- if (x != 0 && ! jump_back_p (x, insn))
- /* We have no opposing jump;
- cannot cross jump this insn. */
- x = 0;
-
- newjpos = 0;
- /* TARGET is nonzero if it is ok to cross jump
- to code before TARGET. If so, see if matches. */
- if (x != 0)
- find_cross_jump (insn, x, 2,
- &newjpos, &newlpos);
-
- if (newjpos != 0)
- {
- do_cross_jump (insn, newjpos, newlpos);
- /* Make the old conditional jump
- into an unconditional one. */
- SET_SRC (PATTERN (insn))
- = gen_rtx_LABEL_REF (VOIDmode, JUMP_LABEL (insn));
- INSN_CODE (insn) = -1;
- emit_barrier_after (insn);
- /* Add to jump_chain unless this is a new label
- whose UID is too large. */
- if (INSN_UID (JUMP_LABEL (insn)) < max_jump_chain)
- {
- jump_chain[INSN_UID (insn)]
- = jump_chain[INSN_UID (JUMP_LABEL (insn))];
- jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
- }
- changed = 1;
- next = insn;
- }
- }
-
- /* Cross jumping of unconditional jumps:
- a few differences. */
-
- if (cross_jump && simplejump_p (insn))
- {
- rtx newjpos, newlpos;
- rtx target;
-
- newjpos = 0;
-
- /* TARGET is nonzero if it is ok to cross jump
- to code before TARGET. If so, see if matches. */
- find_cross_jump (insn, JUMP_LABEL (insn), 1,
- &newjpos, &newlpos);
-
- /* If cannot cross jump to code before the label,
- see if we can cross jump to another jump to
- the same label. */
- /* Try each other jump to this label. */
- if (INSN_UID (JUMP_LABEL (insn)) < max_uid)
- for (target = jump_chain[INSN_UID (JUMP_LABEL (insn))];
- target != 0 && newjpos == 0;
- target = jump_chain[INSN_UID (target)])
- if (target != insn
- && JUMP_LABEL (target) == JUMP_LABEL (insn)
- /* Ignore TARGET if it's deleted. */
- && ! INSN_DELETED_P (target))
- find_cross_jump (insn, target, 2,
- &newjpos, &newlpos);
-
- if (newjpos != 0)
- {
- do_cross_jump (insn, newjpos, newlpos);
- changed = 1;
- next = insn;
- }
- }
-
- /* This code was dead in the previous jump.c! */
- if (cross_jump && GET_CODE (PATTERN (insn)) == RETURN)
- {
- /* Return insns all "jump to the same place"
- so we can cross-jump between any two of them. */
-
- rtx newjpos, newlpos, target;
-
- newjpos = 0;
-
- /* If cannot cross jump to code before the label,
- see if we can cross jump to another jump to
- the same label. */
- /* Try each other jump to this label. */
- for (target = jump_chain[0];
- target != 0 && newjpos == 0;
- target = jump_chain[INSN_UID (target)])
- if (target != insn
- && ! INSN_DELETED_P (target)
- && GET_CODE (PATTERN (target)) == RETURN)
- find_cross_jump (insn, target, 2,
- &newjpos, &newlpos);
-
- if (newjpos != 0)
- {
- do_cross_jump (insn, newjpos, newlpos);
- changed = 1;
- next = insn;
- }
- }
- }
- }
-
- first = 0;
- }
-
- /* Delete extraneous line number notes.
- Note that two consecutive notes for different lines are not really
- extraneous. There should be some indication where that line belonged,
- even if it became empty. */
-
- {
- rtx last_note = 0;
-
- for (insn = f; insn; insn = NEXT_INSN (insn))
- if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) >= 0)
- {
- /* Delete this note if it is identical to previous note. */
- if (last_note
- && NOTE_SOURCE_FILE (insn) == NOTE_SOURCE_FILE (last_note)
- && NOTE_LINE_NUMBER (insn) == NOTE_LINE_NUMBER (last_note))
- {
- delete_insn (insn);
- continue;
- }
-
- last_note = insn;
- }
- }
-
- /* CAN_REACH_END is persistent for each function. Once set it should
- not be cleared. This is especially true for the case where we
- delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by
- the front-end before compiling each function. */
- if (! minimal && calculate_can_reach_end (last_insn, optimize != 0))
- can_reach_end = 1;
-
-end:
- /* Clean up. */
- free (jump_chain);
- jump_chain = 0;
-}
-\f
-/* Initialize LABEL_NUSES and JUMP_LABEL fields. Delete any REG_LABEL
- notes whose labels don't occur in the insn any more. Returns the
- largest INSN_UID found. */
-static int
-init_label_info (f)
- rtx f;
-{
- int largest_uid = 0;
- rtx insn;
-
- for (insn = f; insn; insn = NEXT_INSN (insn))
- {
- if (GET_CODE (insn) == CODE_LABEL)
- LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);
- else if (GET_CODE (insn) == JUMP_INSN)
- JUMP_LABEL (insn) = 0;
- else if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
- {
- rtx note, next;
-
- for (note = REG_NOTES (insn); note; note = next)
- {
- next = XEXP (note, 1);
- if (REG_NOTE_KIND (note) == REG_LABEL
- && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
- remove_note (insn, note);
- }
- }
- if (INSN_UID (insn) > largest_uid)
- largest_uid = INSN_UID (insn);
- }
-
- return largest_uid;
-}
-
-/* Delete insns following barriers, up to next label.
-
- Also delete no-op jumps created by gcse. */
-
-static void
-delete_barrier_successors (f)
- rtx f;
-{
- rtx insn;
-
- for (insn = f; insn;)
- {
- if (GET_CODE (insn) == BARRIER)
- {
- insn = NEXT_INSN (insn);
-
- never_reached_warning (insn);
-
- while (insn != 0 && GET_CODE (insn) != CODE_LABEL)
- {
- if (GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
- insn = NEXT_INSN (insn);
- else
- insn = delete_insn (insn);
- }
- /* INSN is now the code_label. */
- }
-
- /* Also remove (set (pc) (pc)) insns which can be created by
- gcse. We eliminate such insns now to avoid having them
- cause problems later. */
- else if (GET_CODE (insn) == JUMP_INSN
- && GET_CODE (PATTERN (insn)) == SET
- && SET_SRC (PATTERN (insn)) == pc_rtx
- && SET_DEST (PATTERN (insn)) == pc_rtx)
- insn = delete_insn (insn);
-
- else
- insn = NEXT_INSN (insn);
- }
-}
-
-/* Mark the label each jump jumps to.
- Combine consecutive labels, and count uses of labels.
-
- For each label, make a chain (using `jump_chain')
- of all the *unconditional* jumps that jump to it;
- also make a chain of all returns.
-
- CROSS_JUMP indicates whether we are doing cross jumping
- and if we are whether we will be paying attention to
- death notes or not. */
-
-static void
-mark_all_labels (f, cross_jump)
- rtx f;
- int cross_jump;
-{
- rtx insn;
-
- for (insn = f; insn; insn = NEXT_INSN (insn))
- if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
- {
- mark_jump_label (PATTERN (insn), insn, cross_jump, 0);
- if (! INSN_DELETED_P (insn) && GET_CODE (insn) == JUMP_INSN)
- {
- if (JUMP_LABEL (insn) != 0 && simplejump_p (insn))
- {
- jump_chain[INSN_UID (insn)]
- = jump_chain[INSN_UID (JUMP_LABEL (insn))];
- jump_chain[INSN_UID (JUMP_LABEL (insn))] = insn;
- }
- if (GET_CODE (PATTERN (insn)) == RETURN)
- {
- jump_chain[INSN_UID (insn)] = jump_chain[0];
- jump_chain[0] = insn;
- }
- }
- }
-}
-
-/* Delete all labels already not referenced.
- Also find and return the last insn. */
-
-static rtx
-delete_unreferenced_labels (f)
- rtx f;
-{
- rtx final = NULL_RTX;
- rtx insn;
-
- for (insn = f; insn; )
- {
- if (GET_CODE (insn) == CODE_LABEL
- && LABEL_NUSES (insn) == 0
- && LABEL_ALTERNATE_NAME (insn) == NULL)
- insn = delete_insn (insn);
- else
- {
- final = insn;
- insn = NEXT_INSN (insn);
- }
- }
-
- return final;
-}
-
-/* Delete various simple forms of moves which have no necessary
- side effect. */
-
-static void
-delete_noop_moves (f)
- rtx f;
-{
- rtx insn, next;
-
- for (insn = f; insn; )
- {
- next = NEXT_INSN (insn);
-
- if (GET_CODE (insn) == INSN)
- {
- register rtx body = PATTERN (insn);
-
- /* Detect and delete no-op move instructions
- resulting from not allocating a parameter in a register. */
-
- if (GET_CODE (body) == SET
- && (SET_DEST (body) == SET_SRC (body)
- || (GET_CODE (SET_DEST (body)) == MEM
- && GET_CODE (SET_SRC (body)) == MEM
- && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
- && ! (GET_CODE (SET_DEST (body)) == MEM
- && MEM_VOLATILE_P (SET_DEST (body)))
- && ! (GET_CODE (SET_SRC (body)) == MEM
- && MEM_VOLATILE_P (SET_SRC (body))))
- delete_computation (insn);
-
- /* Detect and ignore no-op move instructions
- resulting from smart or fortuitous register allocation. */
-
- else if (GET_CODE (body) == SET)
- {
- int sreg = true_regnum (SET_SRC (body));
- int dreg = true_regnum (SET_DEST (body));
-
- if (sreg == dreg && sreg >= 0)
- delete_insn (insn);
- else if (sreg >= 0 && dreg >= 0)
- {
- rtx trial;
- rtx tem = find_equiv_reg (NULL_RTX, insn, 0,
- sreg, NULL_PTR, dreg,
- GET_MODE (SET_SRC (body)));
-
- if (tem != 0
- && GET_MODE (tem) == GET_MODE (SET_DEST (body)))
- {
- /* DREG may have been the target of a REG_DEAD note in
- the insn which makes INSN redundant. If so, reorg
- would still think it is dead. So search for such a
- note and delete it if we find it. */
- if (! find_regno_note (insn, REG_UNUSED, dreg))
- for (trial = prev_nonnote_insn (insn);
- trial && GET_CODE (trial) != CODE_LABEL;
- trial = prev_nonnote_insn (trial))
- if (find_regno_note (trial, REG_DEAD, dreg))
- {
- remove_death (dreg, trial);
- break;
- }
-
- /* Deleting insn could lose a death-note for SREG. */
- if ((trial = find_regno_note (insn, REG_DEAD, sreg)))
- {
- /* Change this into a USE so that we won't emit
- code for it, but still can keep the note. */
- PATTERN (insn)
- = gen_rtx_USE (VOIDmode, XEXP (trial, 0));
- INSN_CODE (insn) = -1;
- /* Remove all reg notes but the REG_DEAD one. */
- REG_NOTES (insn) = trial;
- XEXP (trial, 1) = NULL_RTX;
- }
- else
- delete_insn (insn);
- }
- }
- else if (dreg >= 0 && CONSTANT_P (SET_SRC (body))
- && find_equiv_reg (SET_SRC (body), insn, 0, dreg,
- NULL_PTR, 0,
- GET_MODE (SET_DEST (body))))
- {
- /* This handles the case where we have two consecutive
- assignments of the same constant to pseudos that didn't
- get a hard reg. Each SET from the constant will be
- converted into a SET of the spill register and an
- output reload will be made following it. This produces
- two loads of the same constant into the same spill
- register. */
-
- rtx in_insn = insn;
-
- /* Look back for a death note for the first reg.
- If there is one, it is no longer accurate. */
- while (in_insn && GET_CODE (in_insn) != CODE_LABEL)
- {
- if ((GET_CODE (in_insn) == INSN
- || GET_CODE (in_insn) == JUMP_INSN)
- && find_regno_note (in_insn, REG_DEAD, dreg))
- {
- remove_death (dreg, in_insn);
- break;
- }
- in_insn = PREV_INSN (in_insn);
- }
-
- /* Delete the second load of the value. */
- delete_insn (insn);
- }
- }
- else if (GET_CODE (body) == PARALLEL)
- {
- /* If each part is a set between two identical registers or
- a USE or CLOBBER, delete the insn. */
- int i, sreg, dreg;
- rtx tem;
-
- for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
- {
- tem = XVECEXP (body, 0, i);
- if (GET_CODE (tem) == USE || GET_CODE (tem) == CLOBBER)
- continue;
-
- if (GET_CODE (tem) != SET
- || (sreg = true_regnum (SET_SRC (tem))) < 0
- || (dreg = true_regnum (SET_DEST (tem))) < 0
- || dreg != sreg)
- break;
- }
-
- if (i < 0)
- delete_insn (insn);
- }
- /* Also delete insns to store bit fields if they are no-ops. */
- /* Not worth the hair to detect this in the big-endian case. */
- else if (! BYTES_BIG_ENDIAN
- && GET_CODE (body) == SET
- && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
- && XEXP (SET_DEST (body), 2) == const0_rtx
- && XEXP (SET_DEST (body), 0) == SET_SRC (body)
- && ! (GET_CODE (SET_SRC (body)) == MEM
- && MEM_VOLATILE_P (SET_SRC (body))))
- delete_insn (insn);
- }
- insn = next;
- }
-}
-
-/* See if there is still a NOTE_INSN_FUNCTION_END in this function.
- If so indicate that this function can drop off the end by returning
- 1, else return 0.
-
- CHECK_DELETED indicates whether we must check if the note being
- searched for has the deleted flag set.
-
- DELETE_FINAL_NOTE indicates whether we should delete the note
- if we find it. */
-
-static int
-calculate_can_reach_end (last, delete_final_note)
- rtx last;
- int delete_final_note;
-{
- rtx insn = last;
- int n_labels = 1;
-
- while (insn != NULL_RTX)
- {
- int ok = 0;
-
- /* One label can follow the end-note: the return label. */
- if (GET_CODE (insn) == CODE_LABEL && n_labels-- > 0)
- ok = 1;
- /* Ordinary insns can follow it if returning a structure. */
- else if (GET_CODE (insn) == INSN)
- ok = 1;
- /* If machine uses explicit RETURN insns, no epilogue,
- then one of them follows the note. */
- else if (GET_CODE (insn) == JUMP_INSN
- && GET_CODE (PATTERN (insn)) == RETURN)
- ok = 1;
- /* A barrier can follow the return insn. */
- else if (GET_CODE (insn) == BARRIER)
- ok = 1;
- /* Other kinds of notes can follow also. */
- else if (GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) != NOTE_INSN_FUNCTION_END)
- ok = 1;
-
- if (ok != 1)
- break;
-
- insn = PREV_INSN (insn);
- }
-
- /* See if we backed up to the appropriate type of note. */
- if (insn != NULL_RTX
- && GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END)
- {
- if (delete_final_note)
- delete_insn (insn);
- return 1;
- }
-
- return 0;
-}
-
-/* LOOP_START is a NOTE_INSN_LOOP_BEG note that is followed by an unconditional
- jump. Assume that this unconditional jump is to the exit test code. If
- the code is sufficiently simple, make a copy of it before INSN,
- followed by a jump to the exit of the loop. Then delete the unconditional
- jump after INSN.
-
- Return 1 if we made the change, else 0.
-
- This is only safe immediately after a regscan pass because it uses the
- values of regno_first_uid and regno_last_uid. */
-
-static int
-duplicate_loop_exit_test (loop_start)
- rtx loop_start;
-{
- rtx insn, set, reg, p, link;
- rtx copy = 0, first_copy = 0;
- int num_insns = 0;
- rtx exitcode = NEXT_INSN (JUMP_LABEL (next_nonnote_insn (loop_start)));
- rtx lastexit;
- int max_reg = max_reg_num ();
- rtx *reg_map = 0;
-
- /* Scan the exit code. We do not perform this optimization if any insn:
-
- is a CALL_INSN
- is a CODE_LABEL
- has a REG_RETVAL or REG_LIBCALL note (hard to adjust)
- is a NOTE_INSN_LOOP_BEG because this means we have a nested loop
- is a NOTE_INSN_BLOCK_{BEG,END} because duplicating these notes
- is not valid.
-
- We also do not do this if we find an insn with ASM_OPERANDS. While
- this restriction should not be necessary, copying an insn with
- ASM_OPERANDS can confuse asm_noperands in some cases.
-
- Also, don't do this if the exit code is more than 20 insns. */
-
- for (insn = exitcode;
- insn
- && ! (GET_CODE (insn) == NOTE
- && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END);
- insn = NEXT_INSN (insn))
- {
- switch (GET_CODE (insn))
- {
- case CODE_LABEL:
- case CALL_INSN:
- return 0;
- case NOTE:
- /* We could be in front of the wrong NOTE_INSN_LOOP_END if there is
- a jump immediately after the loop start that branches outside
- the loop but within an outer loop, near the exit test.
- If we copied this exit test and created a phony
- NOTE_INSN_LOOP_VTOP, this could make instructions immediately
- before the exit test look like these could be safely moved
- out of the loop even if they actually may be never executed.
- This can be avoided by checking here for NOTE_INSN_LOOP_CONT. */
-
- if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
- return 0;
-
- if (optimize < 2
- && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
- /* If we were to duplicate this code, we would not move
- the BLOCK notes, and so debugging the moved code would
- be difficult. Thus, we only move the code with -O2 or
- higher. */
- return 0;
-
- break;
- case JUMP_INSN:
- case INSN:
- /* The code below would grossly mishandle REG_WAS_0 notes,
- so get rid of them here. */
- while ((p = find_reg_note (insn, REG_WAS_0, NULL_RTX)) != 0)
- remove_note (insn, p);
- if (++num_insns > 20
- || find_reg_note (insn, REG_RETVAL, NULL_RTX)
- || find_reg_note (insn, REG_LIBCALL, NULL_RTX))
- return 0;
- break;
- default:
- break;
- }
- }
-
- /* Unless INSN is zero, we can do the optimization. */
- if (insn == 0)
- return 0;
-
- lastexit = insn;
-
- /* See if any insn sets a register only used in the loop exit code and
- not a user variable. If so, replace it with a new register. */
- for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
- if (GET_CODE (insn) == INSN
- && (set = single_set (insn)) != 0
- && ((reg = SET_DEST (set), GET_CODE (reg) == REG)
- || (GET_CODE (reg) == SUBREG
- && (reg = SUBREG_REG (reg), GET_CODE (reg) == REG)))
- && REGNO (reg) >= FIRST_PSEUDO_REGISTER
- && REGNO_FIRST_UID (REGNO (reg)) == INSN_UID (insn))
- {
- for (p = NEXT_INSN (insn); p != lastexit; p = NEXT_INSN (p))
- if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (p))
- break;
-
- if (p != lastexit)
- {
- /* We can do the replacement. Allocate reg_map if this is the
- first replacement we found. */
- if (reg_map == 0)
- reg_map = (rtx *) xcalloc (max_reg, sizeof (rtx));
-
- REG_LOOP_TEST_P (reg) = 1;
-
- reg_map[REGNO (reg)] = gen_reg_rtx (GET_MODE (reg));
- }
- }
-
- /* Now copy each insn. */
- for (insn = exitcode; insn != lastexit; insn = NEXT_INSN (insn))
- {
- switch (GET_CODE (insn))
- {
- case BARRIER:
- copy = emit_barrier_before (loop_start);
- break;
- case NOTE:
- /* Only copy line-number notes. */
- if (NOTE_LINE_NUMBER (insn) >= 0)
- {
- copy = emit_note_before (NOTE_LINE_NUMBER (insn), loop_start);
- NOTE_SOURCE_FILE (copy) = NOTE_SOURCE_FILE (insn);
- }
- break;
-
- case INSN:
- copy = emit_insn_before (copy_insn (PATTERN (insn)), loop_start);
- if (reg_map)
- replace_regs (PATTERN (copy), reg_map, max_reg, 1);
-
- mark_jump_label (PATTERN (copy), copy, 0, 0);
-
- /* Copy all REG_NOTES except REG_LABEL since mark_jump_label will
- make them. */
- for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
- if (REG_NOTE_KIND (link) != REG_LABEL)
- REG_NOTES (copy)
- = copy_insn_1 (gen_rtx_EXPR_LIST (REG_NOTE_KIND (link),
- XEXP (link, 0),
- REG_NOTES (copy)));
- if (reg_map && REG_NOTES (copy))
- replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
- break;
-
- case JUMP_INSN:
- copy = emit_jump_insn_before (copy_insn (PATTERN (insn)), loop_start);
- if (reg_map)
- replace_regs (PATTERN (copy), reg_map, max_reg, 1);
- mark_jump_label (PATTERN (copy), copy, 0, 0);
- if (REG_NOTES (insn))
- {
- REG_NOTES (copy) = copy_insn_1 (REG_NOTES (insn));
- if (reg_map)
- replace_regs (REG_NOTES (copy), reg_map, max_reg, 1);
- }
-
- /* If this is a simple jump, add it to the jump chain. */
-
- if (INSN_UID (copy) < max_jump_chain && JUMP_LABEL (copy)
- && simplejump_p (copy))
- {
- jump_chain[INSN_UID (copy)]
- = jump_chain[INSN_UID (JUMP_LABEL (copy))];
- jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
- }
- break;
-
- default:
- abort ();
- }
-
- /* Record the first insn we copied. We need it so that we can
- scan the copied insns for new pseudo registers. */
- if (! first_copy)
- first_copy = copy;
- }
-
- /* Now clean up by emitting a jump to the end label and deleting the jump
- at the start of the loop. */
- if (! copy || GET_CODE (copy) != BARRIER)
- {
- copy = emit_jump_insn_before (gen_jump (get_label_after (insn)),
- loop_start);
-
- /* Record the first insn we copied. We need it so that we can
- scan the copied insns for new pseudo registers. This may not
- be strictly necessary since we should have copied at least one
- insn above. But I am going to be safe. */
- if (! first_copy)
- first_copy = copy;
-
- mark_jump_label (PATTERN (copy), copy, 0, 0);
- if (INSN_UID (copy) < max_jump_chain
- && INSN_UID (JUMP_LABEL (copy)) < max_jump_chain)
- {
- jump_chain[INSN_UID (copy)]
- = jump_chain[INSN_UID (JUMP_LABEL (copy))];
- jump_chain[INSN_UID (JUMP_LABEL (copy))] = copy;
- }
- emit_barrier_before (loop_start);
- }
-
- /* Now scan from the first insn we copied to the last insn we copied
- (copy) for new pseudo registers. Do this after the code to jump to
- the end label since that might create a new pseudo too. */
- reg_scan_update (first_copy, copy, max_reg);
-
- /* Mark the exit code as the virtual top of the converted loop. */
- emit_note_before (NOTE_INSN_LOOP_VTOP, exitcode);
-
- delete_insn (next_nonnote_insn (loop_start));
-
- /* Clean up. */
- if (reg_map)
- free (reg_map);
-
- return 1;
-}
-\f
-/* Move all block-beg, block-end, loop-beg, loop-cont, loop-vtop, and
- loop-end notes between START and END out before START. Assume that
- END is not such a note. START may be such a note. Returns the value
- of the new starting insn, which may be different if the original start
- was such a note. */
-
-rtx
-squeeze_notes (start, end)
- rtx start, end;
-{
- rtx insn;
- rtx next;
-
- for (insn = start; insn != end; insn = next)
- {
- next = NEXT_INSN (insn);
- if (GET_CODE (insn) == NOTE
- && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT
- || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP))
- {
- if (insn == start)
- start = next;
- else
- {
- rtx prev = PREV_INSN (insn);
- PREV_INSN (insn) = PREV_INSN (start);
- NEXT_INSN (insn) = start;
- NEXT_INSN (PREV_INSN (insn)) = insn;
- PREV_INSN (NEXT_INSN (insn)) = insn;
- NEXT_INSN (prev) = next;
- PREV_INSN (next) = prev;
- }
- }
- }
-
- return start;
-}
-\f
-/* Compare the instructions before insn E1 with those before E2
- to find an opportunity for cross jumping.
- (This means detecting identical sequences of insns followed by
- jumps to the same place, or followed by a label and a jump
- to that label, and replacing one with a jump to the other.)
-
- Assume E1 is a jump that jumps to label E2
- (that is not always true but it might as well be).
- Find the longest possible equivalent sequences
- and store the first insns of those sequences into *F1 and *F2.
- Store zero there if no equivalent preceding instructions are found.
-
- We give up if we find a label in stream 1.
- Actually we could transfer that label into stream 2. */
-
-static void
-find_cross_jump (e1, e2, minimum, f1, f2)
- rtx e1, e2;
- int minimum;
- rtx *f1, *f2;
-{
- register rtx i1 = e1, i2 = e2;
- register rtx p1, p2;
- int lose = 0;
-
- rtx last1 = 0, last2 = 0;
- rtx afterlast1 = 0, afterlast2 = 0;
-
- *f1 = 0;
- *f2 = 0;
-
- while (1)
- {
- i1 = prev_nonnote_insn (i1);
-
- i2 = PREV_INSN (i2);
- while (i2 && (GET_CODE (i2) == NOTE || GET_CODE (i2) == CODE_LABEL))
- i2 = PREV_INSN (i2);
-
- if (i1 == 0)
- break;
-
- /* Don't allow the range of insns preceding E1 or E2
- to include the other (E2 or E1). */
- if (i2 == e1 || i1 == e2)
- break;
-
- /* If we will get to this code by jumping, those jumps will be
- tensioned to go directly to the new label (before I2),
- so this cross-jumping won't cost extra. So reduce the minimum. */
- if (GET_CODE (i1) == CODE_LABEL)
- {
- --minimum;
- break;
- }
-
- if (i2 == 0 || GET_CODE (i1) != GET_CODE (i2))
- break;
-
- /* Avoid moving insns across EH regions if either of the insns
- can throw. */
- if (flag_exceptions
- && (asynchronous_exceptions || GET_CODE (i1) == CALL_INSN)
- && !in_same_eh_region (i1, i2))
- break;
-
- p1 = PATTERN (i1);
- p2 = PATTERN (i2);
-
- /* If this is a CALL_INSN, compare register usage information.
- If we don't check this on stack register machines, the two
- CALL_INSNs might be merged leaving reg-stack.c with mismatching
- numbers of stack registers in the same basic block.
- If we don't check this on machines with delay slots, a delay slot may
- be filled that clobbers a parameter expected by the subroutine.
-
- ??? We take the simple route for now and assume that if they're
- equal, they were constructed identically. */
-
- if (GET_CODE (i1) == CALL_INSN
- && ! rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
- CALL_INSN_FUNCTION_USAGE (i2)))
- lose = 1;
-
-#ifdef STACK_REGS
- /* If cross_jump_death_matters is not 0, the insn's mode
- indicates whether or not the insn contains any stack-like
- regs. */
-
- if (!lose && cross_jump_death_matters && stack_regs_mentioned (i1))
- {
- /* If register stack conversion has already been done, then
- death notes must also be compared before it is certain that
- the two instruction streams match. */
-
- rtx note;
- HARD_REG_SET i1_regset, i2_regset;
-
- CLEAR_HARD_REG_SET (i1_regset);
- CLEAR_HARD_REG_SET (i2_regset);
-
- for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_DEAD
- && STACK_REG_P (XEXP (note, 0)))
- SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
-
- for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_DEAD
- && STACK_REG_P (XEXP (note, 0)))
- SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
-
- GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
-
- lose = 1;
-
- done:
- ;
- }
-#endif
-
- /* Don't allow old-style asm or volatile extended asms to be accepted
- for cross jumping purposes. It is conceptually correct to allow
- them, since cross-jumping preserves the dynamic instruction order
- even though it is changing the static instruction order. However,
- if an asm is being used to emit an assembler pseudo-op, such as
- the MIPS `.set reorder' pseudo-op, then the static instruction order
- matters and it must be preserved. */
- if (GET_CODE (p1) == ASM_INPUT || GET_CODE (p2) == ASM_INPUT
- || (GET_CODE (p1) == ASM_OPERANDS && MEM_VOLATILE_P (p1))
- || (GET_CODE (p2) == ASM_OPERANDS && MEM_VOLATILE_P (p2)))
- lose = 1;
-
- if (lose || GET_CODE (p1) != GET_CODE (p2)
- || ! rtx_renumbered_equal_p (p1, p2))
- {
- /* The following code helps take care of G++ cleanups. */
- rtx equiv1;
- rtx equiv2;
-
- if (!lose && GET_CODE (p1) == GET_CODE (p2)
- && ((equiv1 = find_reg_note (i1, REG_EQUAL, NULL_RTX)) != 0
- || (equiv1 = find_reg_note (i1, REG_EQUIV, NULL_RTX)) != 0)
- && ((equiv2 = find_reg_note (i2, REG_EQUAL, NULL_RTX)) != 0
- || (equiv2 = find_reg_note (i2, REG_EQUIV, NULL_RTX)) != 0)
- /* If the equivalences are not to a constant, they may
- reference pseudos that no longer exist, so we can't
- use them. */
- && CONSTANT_P (XEXP (equiv1, 0))
- && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
- {
- rtx s1 = single_set (i1);
- rtx s2 = single_set (i2);
- if (s1 != 0 && s2 != 0
- && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
- {
- validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
- validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
- if (! rtx_renumbered_equal_p (p1, p2))
- cancel_changes (0);
- else if (apply_change_group ())
- goto win;
- }
- }