/* Natural loop analysis code for GNU compiler.
- Copyright (C) 2002, 2003 Free Software Foundation, Inc.
+ Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
This file is part of GCC.
#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
+#include "obstack.h"
#include "basic-block.h"
#include "cfgloop.h"
#include "expr.h"
#include "output.h"
-struct unmark_altered_insn_data;
-static void unmark_altered (rtx, rtx, regset);
-static void blocks_invariant_registers (basic_block *, int, regset);
-static void unmark_altered_insn (rtx, rtx, struct unmark_altered_insn_data *);
-static void blocks_single_set_registers (basic_block *, int, rtx *);
-static int invariant_rtx_wrto_regs_p_helper (rtx *, regset);
-static bool invariant_rtx_wrto_regs_p (rtx, regset);
-static rtx test_for_iteration (struct loop_desc *desc, unsigned HOST_WIDE_INT);
-static bool constant_iterations (struct loop_desc *, unsigned HOST_WIDE_INT *,
- bool *);
-static bool simple_loop_exit_p (struct loops *, struct loop *, edge, regset,
- rtx *, struct loop_desc *);
-static rtx variable_initial_value (rtx, regset, rtx, rtx *);
-static rtx variable_initial_values (edge, rtx);
-static bool simple_condition_p (struct loop *, rtx, regset,
- struct loop_desc *);
-static basic_block simple_increment (struct loops *, struct loop *, rtx *,
- struct loop_desc *);
-static rtx count_strange_loop_iterations (rtx, rtx, enum rtx_code,
- int, rtx, enum machine_mode);
-
/* Checks whether BB is executed exactly once in each LOOP iteration. */
+
bool
-just_once_each_iteration_p (struct loops *loops, struct loop *loop, basic_block bb)
+just_once_each_iteration_p (struct loop *loop, basic_block bb)
{
/* It must be executed at least once each iteration. */
- if (!dominated_by_p (loops->cfg.dom, loop->latch, bb))
+ if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
return false;
/* And just once. */
return true;
}
+/* Structure representing edge of a graph. */
-/* Unmarks modified registers; helper to blocks_invariant_registers. */
-static void
-unmark_altered (rtx what, rtx by ATTRIBUTE_UNUSED, regset regs)
-{
- if (GET_CODE (what) == SUBREG)
- what = SUBREG_REG (what);
- if (!REG_P (what))
- return;
- CLEAR_REGNO_REG_SET (regs, REGNO (what));
-}
-
-/* Marks registers that are invariant inside blocks BBS. */
-static void
-blocks_invariant_registers (basic_block *bbs, int nbbs, regset regs)
+struct edge
{
- rtx insn;
- int i;
+ int src, dest; /* Source and destination. */
+ struct edge *pred_next, *succ_next;
+ /* Next edge in predecessor and successor lists. */
+ void *data; /* Data attached to the edge. */
+};
- for (i = 0; i < max_reg_num (); i++)
- SET_REGNO_REG_SET (regs, i);
- for (i = 0; i < nbbs; i++)
- for (insn = bbs[i]->head;
- insn != NEXT_INSN (bbs[i]->end);
- insn = NEXT_INSN (insn))
- if (INSN_P (insn))
- note_stores (PATTERN (insn),
- (void (*) (rtx, rtx, void *)) unmark_altered,
- regs);
-}
+/* Structure representing vertex of a graph. */
-/* Unmarks modified registers; helper to blocks_single_set_registers. */
-struct unmark_altered_insn_data
+struct vertex
{
- rtx *regs;
- rtx insn;
+ struct edge *pred, *succ;
+ /* Lists of predecessors and successors. */
+ int component; /* Number of dfs restarts before reaching the
+ vertex. */
+ int post; /* Postorder number. */
};
-static void
-unmark_altered_insn (rtx what, rtx by ATTRIBUTE_UNUSED,
- struct unmark_altered_insn_data *data)
+/* Structure representing a graph. */
+
+struct graph
{
- int rn;
+ int n_vertices; /* Number of vertices. */
+ struct vertex *vertices;
+ /* The vertices. */
+};
- if (GET_CODE (what) == SUBREG)
- what = SUBREG_REG (what);
- if (!REG_P (what))
- return;
- rn = REGNO (what);
- if (data->regs[rn] == data->insn)
- return;
- data->regs[rn] = NULL;
-}
+/* Dumps graph G into F. */
-/* Marks registers that have just single simple set in BBS; the relevant
- insn is returned in REGS. */
-static void
-blocks_single_set_registers (basic_block *bbs, int nbbs, rtx *regs)
+extern void dump_graph (FILE *, struct graph *);
+void dump_graph (FILE *f, struct graph *g)
{
- rtx insn;
int i;
- struct unmark_altered_insn_data data;
-
- for (i = 0; i < max_reg_num (); i++)
- regs[i] = NULL;
+ struct edge *e;
- for (i = 0; i < nbbs; i++)
- for (insn = bbs[i]->head;
- insn != NEXT_INSN (bbs[i]->end);
- insn = NEXT_INSN (insn))
- {
- rtx set = single_set (insn);
- if (!set)
- continue;
- if (!REG_P (SET_DEST (set)))
- continue;
- regs[REGNO (SET_DEST (set))] = insn;
- }
+ for (i = 0; i < g->n_vertices; i++)
+ {
+ if (!g->vertices[i].pred
+ && !g->vertices[i].succ)
+ continue;
- data.regs = regs;
- for (i = 0; i < nbbs; i++)
- for (insn = bbs[i]->head;
- insn != NEXT_INSN (bbs[i]->end);
- insn = NEXT_INSN (insn))
- {
- if (!INSN_P (insn))
- continue;
- data.insn = insn;
- note_stores (PATTERN (insn),
- (void (*) (rtx, rtx, void *)) unmark_altered_insn,
- &data);
- }
-}
+ fprintf (f, "%d (%d)\t<-", i, g->vertices[i].component);
+ for (e = g->vertices[i].pred; e; e = e->pred_next)
+ fprintf (f, " %d", e->src);
+ fprintf (f, "\n");
-/* Helper for invariant_rtx_wrto_regs_p. */
-static int
-invariant_rtx_wrto_regs_p_helper (rtx *expr, regset invariant_regs)
-{
- switch (GET_CODE (*expr))
- {
- case CC0:
- case PC:
- case UNSPEC_VOLATILE:
- return 1;
-
- case CONST_INT:
- case CONST_DOUBLE:
- case CONST:
- case SYMBOL_REF:
- case LABEL_REF:
- return 0;
-
- case ASM_OPERANDS:
- return MEM_VOLATILE_P (*expr);
-
- case MEM:
- /* If the memory is not constant, assume it is modified. If it is
- constant, we still have to check the address. */
- return !RTX_UNCHANGING_P (*expr);
-
- case REG:
- return !REGNO_REG_SET_P (invariant_regs, REGNO (*expr));
-
- default:
- return 0;
+ fprintf (f, "\t->");
+ for (e = g->vertices[i].succ; e; e = e->succ_next)
+ fprintf (f, " %d", e->dest);
+ fprintf (f, "\n");
}
}
-/* Checks that EXPR is invariant provided that INVARIANT_REGS are invariant. */
-static bool
-invariant_rtx_wrto_regs_p (rtx expr, regset invariant_regs)
-{
- return !for_each_rtx (&expr, (rtx_function) invariant_rtx_wrto_regs_p_helper,
- invariant_regs);
-}
+/* Creates a new graph with N_VERTICES vertices. */
-/* Checks whether CONDITION is a simple comparison in that one of operands
- is register and the other one is invariant in the LOOP. Fills var, lim
- and cond fields in DESC. */
-static bool
-simple_condition_p (struct loop *loop ATTRIBUTE_UNUSED, rtx condition,
- regset invariant_regs, struct loop_desc *desc)
+static struct graph *
+new_graph (int n_vertices)
{
- rtx op0, op1;
+ struct graph *g = xmalloc (sizeof (struct graph));
- /* Check condition. */
- switch (GET_CODE (condition))
- {
- case EQ:
- case NE:
- case LE:
- case LT:
- case GE:
- case GT:
- case GEU:
- case GTU:
- case LEU:
- case LTU:
- break;
- default:
- return false;
- }
-
- /* Of integers or pointers. */
- if (GET_MODE_CLASS (GET_MODE (XEXP (condition, 0))) != MODE_INT
- && GET_MODE_CLASS (GET_MODE (XEXP (condition, 0))) != MODE_PARTIAL_INT)
- return false;
-
- /* One of operands must be a simple register. */
- op0 = XEXP (condition, 0);
- op1 = XEXP (condition, 1);
-
- /* One of operands must be invariant. */
- if (invariant_rtx_wrto_regs_p (op0, invariant_regs))
- {
- /* And the other one must be a register. */
- if (!REG_P (op1))
- return false;
- desc->var = op1;
- desc->lim = op0;
-
- desc->cond = swap_condition (GET_CODE (condition));
- if (desc->cond == UNKNOWN)
- return false;
- return true;
- }
-
- /* Check the other operand. */
- if (!invariant_rtx_wrto_regs_p (op1, invariant_regs))
- return false;
- if (!REG_P (op0))
- return false;
-
- desc->var = op0;
- desc->lim = op1;
-
- desc->cond = GET_CODE (condition);
+ g->n_vertices = n_vertices;
+ g->vertices = xcalloc (n_vertices, sizeof (struct vertex));
- return true;
+ return g;
}
-/* Checks whether DESC->var is incremented/decremented exactly once each
- iteration. Fills in DESC->stride and returns block in that DESC->var is
- modified. */
-static basic_block
-simple_increment (struct loops *loops, struct loop *loop,
- rtx *simple_increment_regs, struct loop_desc *desc)
-{
- rtx mod_insn, set, set_src, set_add;
- basic_block mod_bb;
-
- /* Find insn that modifies var. */
- mod_insn = simple_increment_regs[REGNO (desc->var)];
- if (!mod_insn)
- return NULL;
- mod_bb = BLOCK_FOR_INSN (mod_insn);
-
- /* Check that it is executed exactly once each iteration. */
- if (!just_once_each_iteration_p (loops, loop, mod_bb))
- return NULL;
-
- /* mod_insn must be a simple increment/decrement. */
- set = single_set (mod_insn);
- if (!set)
- abort ();
- if (!rtx_equal_p (SET_DEST (set), desc->var))
- abort ();
-
- set_src = find_reg_equal_equiv_note (mod_insn);
- if (!set_src)
- set_src = SET_SRC (set);
- if (GET_CODE (set_src) != PLUS)
- return NULL;
- if (!rtx_equal_p (XEXP (set_src, 0), desc->var))
- return NULL;
-
- /* Set desc->stride. */
- set_add = XEXP (set_src, 1);
- if (CONSTANT_P (set_add))
- desc->stride = set_add;
- else
- return NULL;
-
- return mod_bb;
-}
+/* Adds an edge from F to T to graph G, with DATA attached. */
-/* Tries to find initial value of VAR in INSN. This value must be invariant
- wrto INVARIANT_REGS. If SET_INSN is not NULL, insn in that var is set is
- placed here. */
-static rtx
-variable_initial_value (rtx insn, regset invariant_regs, rtx var, rtx *set_insn)
+static void
+add_edge (struct graph *g, int f, int t, void *data)
{
- basic_block bb;
- rtx set;
-
- /* Go back through cfg. */
- bb = BLOCK_FOR_INSN (insn);
- while (1)
- {
- for (; insn != bb->head; insn = PREV_INSN (insn))
- {
- if (INSN_P (insn))
- note_stores (PATTERN (insn),
- (void (*) (rtx, rtx, void *)) unmark_altered,
- invariant_regs);
- if (modified_between_p (var, PREV_INSN (insn), NEXT_INSN (insn)))
- break;
- }
-
- if (insn != bb->head)
- {
- /* We found place where var is set. */
- rtx set_dest;
- rtx val;
- rtx note;
-
- set = single_set (insn);
- if (!set)
- return NULL;
- set_dest = SET_DEST (set);
- if (!rtx_equal_p (set_dest, var))
- return NULL;
-
- note = find_reg_equal_equiv_note (insn);
- if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST)
- val = XEXP (note, 0);
- else
- val = SET_SRC (set);
- if (!invariant_rtx_wrto_regs_p (val, invariant_regs))
- return NULL;
-
- if (set_insn)
- *set_insn = insn;
- return val;
- }
+ struct edge *e = xmalloc (sizeof (struct edge));
+ e->src = f;
+ e->dest = t;
+ e->data = data;
- if (bb->pred->pred_next || bb->pred->src == ENTRY_BLOCK_PTR)
- return NULL;
+ e->pred_next = g->vertices[t].pred;
+ g->vertices[t].pred = e;
- bb = bb->pred->src;
- insn = bb->end;
- }
-
- return NULL;
+ e->succ_next = g->vertices[f].succ;
+ g->vertices[f].succ = e;
}
-/* Returns list of definitions of initial value of VAR at Edge. */
-static rtx
-variable_initial_values (edge e, rtx var)
-{
- rtx set_insn, list;
- regset invariant_regs;
- regset_head invariant_regs_head;
- int i;
-
- invariant_regs = INITIALIZE_REG_SET (invariant_regs_head);
- for (i = 0; i < max_reg_num (); i++)
- SET_REGNO_REG_SET (invariant_regs, i);
-
- list = alloc_EXPR_LIST (0, copy_rtx (var), NULL);
-
- if (e->src == ENTRY_BLOCK_PTR)
- return list;
+/* Runs dfs search over vertices of G, from NQ vertices in queue QS.
+ The vertices in postorder are stored into QT. If FORWARD is false,
+ backward dfs is run. */
- set_insn = e->src->end;
- while (REG_P (var)
- && (var = variable_initial_value (set_insn, invariant_regs, var, &set_insn)))
- list = alloc_EXPR_LIST (0, copy_rtx (var), list);
-
- FREE_REG_SET (invariant_regs);
- return list;
-}
-
-/* Counts constant number of iterations of the loop described by DESC;
- returns false if impossible. */
-static bool
-constant_iterations (struct loop_desc *desc, unsigned HOST_WIDE_INT *niter,
- bool *may_be_zero)
+static void
+dfs (struct graph *g, int *qs, int nq, int *qt, bool forward)
{
- rtx test, expr;
- rtx ainit, alim;
+ int i, tick = 0, v, comp = 0, top;
+ struct edge *e;
+ struct edge **stack = xmalloc (sizeof (struct edge *) * g->n_vertices);
- test = test_for_iteration (desc, 0);
- if (test == const0_rtx)
+ for (i = 0; i < g->n_vertices; i++)
{
- *niter = 0;
- *may_be_zero = false;
- return true;
+ g->vertices[i].component = -1;
+ g->vertices[i].post = -1;
}
- *may_be_zero = (test != const_true_rtx);
+#define FST_EDGE(V) (forward ? g->vertices[(V)].succ : g->vertices[(V)].pred)
+#define NEXT_EDGE(E) (forward ? (E)->succ_next : (E)->pred_next)
+#define EDGE_SRC(E) (forward ? (E)->src : (E)->dest)
+#define EDGE_DEST(E) (forward ? (E)->dest : (E)->src)
- /* It would make a little sense to check every with every when we
- know that all but the first alternative are simply registers. */
- for (ainit = desc->var_alts; ainit; ainit = XEXP (ainit, 1))
- {
- alim = XEXP (desc->lim_alts, 0);
- if (!(expr = count_loop_iterations (desc, XEXP (ainit, 0), alim)))
- continue;
- if (GET_CODE (expr) == CONST_INT)
- {
- *niter = INTVAL (expr);
- return true;
- }
- }
- for (alim = XEXP (desc->lim_alts, 1); alim; alim = XEXP (alim, 1))
+ for (i = 0; i < nq; i++)
{
- ainit = XEXP (desc->var_alts, 0);
- if (!(expr = count_loop_iterations (desc, ainit, XEXP (alim, 0))))
+ v = qs[i];
+ if (g->vertices[v].post != -1)
continue;
- if (GET_CODE (expr) == CONST_INT)
- {
- *niter = INTVAL (expr);
- return true;
- }
- }
- return false;
-}
+ g->vertices[v].component = comp++;
+ e = FST_EDGE (v);
+ top = 0;
-/* Attempts to determine a number of iterations of a "strange" loop.
- Its induction variable starts with value INIT, is compared by COND
- with LIM. If POSTINCR, it is incremented after the test. It is incremented
- by STRIDE each iteration and iterates in MODE.
-
- By "strange" we mean loops where induction variable increases in the wrong
- direction wrto comparison, i.e. for (i = 6; i > 5; i++). */
-static rtx
-count_strange_loop_iterations (rtx init, rtx lim, enum rtx_code cond,
- int postincr, rtx stride, enum machine_mode mode)
-{
- rtx rqmt, n_to_wrap, before_wrap, after_wrap;
- rtx mode_min, mode_max;
- int size;
-
- if (!postincr)
- init = simplify_gen_binary (PLUS, mode, init, stride);
+ while (1)
+ {
+ while (e && g->vertices[EDGE_DEST (e)].component != -1)
+ e = NEXT_EDGE (e);
- /* If we are able to prove that we don't pass the first test, we are
- done. */
- rqmt = simplify_gen_relational (cond, SImode, mode, init, lim);
- if (rqmt == const0_rtx)
- return const0_rtx;
+ if (!e)
+ {
+ if (qt)
+ qt[tick] = v;
+ g->vertices[v].post = tick++;
- /* And if we don't know we pass it, the things are too complicated for us. */
- if (rqmt != const_true_rtx)
- return NULL_RTX;
+ if (!top)
+ break;
- switch (cond)
- {
- case GE:
- case GT:
- case LE:
- case LT:
- size = GET_MODE_BITSIZE (mode);
- mode_min = GEN_INT (-((unsigned HOST_WIDEST_INT) 1 << (size - 1)));
- mode_max = GEN_INT (((unsigned HOST_WIDEST_INT) 1 << (size - 1)) - 1);
-
- break;
-
- case GEU:
- case GTU:
- case LEU:
- case LTU:
- case EQ:
- mode_min = const0_rtx;
- mode_max = simplify_gen_binary (MINUS, mode, const0_rtx, const1_rtx);
- break;
-
- default:
- abort ();
- }
+ e = stack[--top];
+ v = EDGE_SRC (e);
+ e = NEXT_EDGE (e);
+ continue;
+ }
- switch (cond)
- {
- case EQ:
- /* This iterates once, as init == lim. */
- return const1_rtx;
-
- /* The behavior is undefined in signed cases. Never mind, we still
- try to behave sanely. */
- case GE:
- case GT:
- case GEU:
- case GTU:
- if (INTVAL (stride) <= 0)
- abort ();
- n_to_wrap = simplify_gen_binary (MINUS, mode, mode_max, copy_rtx (init));
- n_to_wrap = simplify_gen_binary (UDIV, mode, n_to_wrap, stride);
- before_wrap = simplify_gen_binary (MULT, mode,
- copy_rtx (n_to_wrap), stride);
- before_wrap = simplify_gen_binary (PLUS, mode,
- before_wrap, copy_rtx (init));
- after_wrap = simplify_gen_binary (PLUS, mode,
- before_wrap, stride);
- if (GET_CODE (after_wrap) != CONST_INT)
- {
- after_wrap = simplify_gen_binary (PLUS, mode, mode_min, stride);
- after_wrap = simplify_gen_binary (MINUS, mode, after_wrap, const1_rtx);
+ stack[top++] = e;
+ v = EDGE_DEST (e);
+ e = FST_EDGE (v);
+ g->vertices[v].component = comp - 1;
}
- break;
-
- case LE:
- case LT:
- case LEU:
- case LTU:
- if (INTVAL (stride) >= 0)
- abort ();
- stride = simplify_gen_unary (NEG, mode, stride, mode);
- n_to_wrap = simplify_gen_binary (MINUS, mode, copy_rtx (init), mode_min);
- n_to_wrap = simplify_gen_binary (UDIV, mode, n_to_wrap, stride);
- before_wrap = simplify_gen_binary (MULT, mode,
- copy_rtx (n_to_wrap), stride);
- before_wrap = simplify_gen_binary (MINUS, mode,
- copy_rtx (init), before_wrap);
- after_wrap = simplify_gen_binary (MINUS, mode,
- before_wrap, stride);
- if (GET_CODE (after_wrap) != CONST_INT)
- {
- after_wrap = simplify_gen_binary (MINUS, mode, mode_max, stride);
- after_wrap = simplify_gen_binary (PLUS, mode, after_wrap, const1_rtx);
- }
- break;
- default:
- abort ();
}
- /* If this is const_true_rtx and we did not take a conservative approximation
- of after_wrap above, we might iterate the calculation (but of course we
- would have to take care about infinite cases). Ignore this for now. */
- rqmt = simplify_gen_relational (cond, SImode, mode, after_wrap, lim);
- if (rqmt != const0_rtx)
- return NULL_RTX;
-
- return simplify_gen_binary (PLUS, mode, n_to_wrap, const1_rtx);
+ free (stack);
}
-/* Return RTX expression representing number of iterations of loop as bounded
- by test described by DESC (in the case loop really has multiple exit
- edges, fewer iterations may happen in the practice).
+/* Marks the edge E in graph G irreducible if it connects two vertices in the
+ same scc. */
- Return NULL if it is unknown. Additionally the value may be invalid for
- paradoxical loop (lets define paradoxical loops as loops whose test is
- failing at -1th iteration, for instance "for (i=5;i<1;i++);").
-
- These cases needs to be either cared by copying the loop test in the front
- of loop or keeping the test in first iteration of loop.
-
- When INIT/LIM are set, they are used instead of var/lim of DESC. */
-rtx
-count_loop_iterations (struct loop_desc *desc, rtx init, rtx lim)
+static void
+check_irred (struct graph *g, struct edge *e)
{
- enum rtx_code cond = desc->cond;
- rtx stride = desc->stride;
- rtx mod, exp;
-
- /* Give up on floating point modes and friends. It can be possible to do
- the job for constant loop bounds, but it is probably not worthwhile. */
- if (!INTEGRAL_MODE_P (GET_MODE (desc->var)))
- return NULL;
-
- init = copy_rtx (init ? init : desc->var);
- lim = copy_rtx (lim ? lim : desc->lim);
+ edge real = e->data;
- /* Ensure that we always handle the condition to stay inside loop. */
- if (desc->neg)
- cond = reverse_condition (cond);
+ /* All edges should lead from a component with higher number to the
+ one with lower one. */
+ gcc_assert (g->vertices[e->src].component >= g->vertices[e->dest].component);
- /* Compute absolute value of the difference of initial and final value. */
- if (INTVAL (stride) > 0)
- {
- /* Handle strange tests specially. */
- if (cond == EQ || cond == GE || cond == GT || cond == GEU
- || cond == GTU)
- return count_strange_loop_iterations (init, lim, cond, desc->postincr,
- stride, GET_MODE (desc->var));
- exp = simplify_gen_binary (MINUS, GET_MODE (desc->var),
- lim, init);
- }
- else
- {
- /* Bypass nonsensical tests. */
- if (cond == EQ || cond == LE || cond == LT || cond == LEU
- || cond == LTU)
- return count_strange_loop_iterations (init, lim, cond, desc->postincr,
- stride, GET_MODE (desc->var));
- exp = simplify_gen_binary (MINUS, GET_MODE (desc->var),
- init, lim);
- stride = simplify_gen_unary (NEG, GET_MODE (desc->var),
- stride, GET_MODE (desc->var));
- }
-
- /* Normalize difference so the value is always first examined
- and later incremented. */
-
- if (!desc->postincr)
- exp = simplify_gen_binary (MINUS, GET_MODE (desc->var),
- exp, stride);
-
- /* Determine delta caused by exit condition. */
- switch (cond)
- {
- case NE:
- /* For NE tests, make sure that the iteration variable won't miss
- the final value. If EXP mod STRIDE is not zero, then the
- iteration variable will overflow before the loop exits, and we
- can not calculate the number of iterations easily. */
- if (stride != const1_rtx
- && (simplify_gen_binary (UMOD, GET_MODE (desc->var), exp, stride)
- != const0_rtx))
- return NULL;
- break;
- case LT:
- case GT:
- case LTU:
- case GTU:
- break;
- case LE:
- case GE:
- case LEU:
- case GEU:
- exp = simplify_gen_binary (PLUS, GET_MODE (desc->var),
- exp, const1_rtx);
- break;
- default:
- abort ();
- }
-
- if (stride != const1_rtx)
- {
- /* Number of iterations is now (EXP + STRIDE - 1 / STRIDE),
- but we need to take care for overflows. */
-
- mod = simplify_gen_binary (UMOD, GET_MODE (desc->var), exp, stride);
-
- /* This is dirty trick. When we can't compute number of iterations
- to be constant, we simply ignore the possible overflow, as
- runtime unroller always use power of 2 amounts and does not
- care about possible lost bits. */
-
- if (GET_CODE (mod) != CONST_INT)
- {
- rtx stridem1 = simplify_gen_binary (PLUS, GET_MODE (desc->var),
- stride, constm1_rtx);
- exp = simplify_gen_binary (PLUS, GET_MODE (desc->var),
- exp, stridem1);
- exp = simplify_gen_binary (UDIV, GET_MODE (desc->var), exp, stride);
- }
- else
- {
- exp = simplify_gen_binary (UDIV, GET_MODE (desc->var), exp, stride);
- if (mod != const0_rtx)
- exp = simplify_gen_binary (PLUS, GET_MODE (desc->var),
- exp, const1_rtx);
- }
- }
-
- if (rtl_dump_file)
- {
- fprintf (rtl_dump_file, "; Number of iterations: ");
- print_simple_rtl (rtl_dump_file, exp);
- fprintf (rtl_dump_file, "\n");
- }
-
- return exp;
-}
-
-/* Return simplified RTX expression representing the value of test
- described of DESC at given iteration of loop. */
+ if (g->vertices[e->src].component != g->vertices[e->dest].component)
+ return;
-static rtx
-test_for_iteration (struct loop_desc *desc, unsigned HOST_WIDE_INT iter)
-{
- enum rtx_code cond = desc->cond;
- rtx exp = XEXP (desc->var_alts, 0);
- rtx addval;
-
- /* Give up on floating point modes and friends. It can be possible to do
- the job for constant loop bounds, but it is probably not worthwhile. */
- if (!INTEGRAL_MODE_P (GET_MODE (desc->var)))
- return NULL;
-
- /* Ensure that we always handle the condition to stay inside loop. */
- if (desc->neg)
- cond = reverse_condition (cond);
-
- /* Compute the value of induction variable. */
- addval = simplify_gen_binary (MULT, GET_MODE (desc->var),
- desc->stride,
- gen_int_mode (desc->postincr
- ? iter : iter + 1,
- GET_MODE (desc->var)));
- exp = simplify_gen_binary (PLUS, GET_MODE (desc->var), exp, addval);
- /* Test at given condition. */
- exp = simplify_gen_relational (cond, SImode,
- GET_MODE (desc->var), exp, desc->lim);
-
- if (rtl_dump_file)
- {
- fprintf (rtl_dump_file, "; Conditional to continue loop at "
- HOST_WIDE_INT_PRINT_UNSIGNED "th iteration: ", iter);
- print_simple_rtl (rtl_dump_file, exp);
- fprintf (rtl_dump_file, "\n");
- }
- return exp;
+ real->flags |= EDGE_IRREDUCIBLE_LOOP;
+ if (flow_bb_inside_loop_p (real->src->loop_father, real->dest))
+ real->src->flags |= BB_IRREDUCIBLE_LOOP;
}
+/* Runs CALLBACK for all edges in G. */
-/* Tests whether exit at EXIT_EDGE from LOOP is simple. Returns simple loop
- description joined to it in in DESC. INVARIANT_REGS and SINGLE_SET_REGS
- are results of blocks_{invariant,single_set}_regs over BODY. */
-static bool
-simple_loop_exit_p (struct loops *loops, struct loop *loop, edge exit_edge,
- regset invariant_regs, rtx *single_set_regs,
- struct loop_desc *desc)
+static void
+for_each_edge (struct graph *g,
+ void (callback) (struct graph *, struct edge *))
{
- basic_block mod_bb, exit_bb;
- int fallthru_out;
- rtx condition;
- edge ei, e;
-
- exit_bb = exit_edge->src;
-
- fallthru_out = (exit_edge->flags & EDGE_FALLTHRU);
-
- if (!exit_bb)
- return false;
-
- /* It must be tested (at least) once during any iteration. */
- if (!dominated_by_p (loops->cfg.dom, loop->latch, exit_bb))
- return false;
-
- /* It must end in a simple conditional jump. */
- if (!any_condjump_p (exit_bb->end))
- return false;
-
- ei = exit_bb->succ;
- if (ei == exit_edge)
- ei = ei->succ_next;
-
- desc->out_edge = exit_edge;
- desc->in_edge = ei;
-
- /* Condition must be a simple comparison in that one of operands
- is register and the other one is invariant. */
- if (!(condition = get_condition (exit_bb->end, NULL)))
- return false;
-
- if (!simple_condition_p (loop, condition, invariant_regs, desc))
- return false;
-
- /* Var must be simply incremented or decremented in exactly one insn that
- is executed just once every iteration. */
- if (!(mod_bb = simple_increment (loops, loop, single_set_regs, desc)))
- return false;
-
- /* OK, it is simple loop. Now just fill in remaining info. */
- desc->postincr = !dominated_by_p (loops->cfg.dom, exit_bb, mod_bb);
- desc->neg = !fallthru_out;
-
- /* Find initial value of var and alternative values for lim. */
- e = loop_preheader_edge (loop);
- desc->var_alts = variable_initial_values (e, desc->var);
- desc->lim_alts = variable_initial_values (e, desc->lim);
+ struct edge *e;
+ int i;
- /* Number of iterations. */
- desc->const_iter =
- constant_iterations (desc, &desc->niter, &desc->may_be_zero);
- if (!desc->const_iter && !count_loop_iterations (desc, NULL, NULL))
- return false;
- return true;
+ for (i = 0; i < g->n_vertices; i++)
+ for (e = g->vertices[i].succ; e; e = e->succ_next)
+ callback (g, e);
}
-/* Tests whether LOOP is simple for loop. Returns simple loop description
- in DESC. */
-bool
-simple_loop_p (struct loops *loops, struct loop *loop, struct loop_desc *desc)
-{
- unsigned i;
- basic_block *body;
- edge e;
- struct loop_desc act;
- bool any = false;
- regset invariant_regs;
- regset_head invariant_regs_head;
- rtx *single_set_regs;
- int n_branches;
-
- body = get_loop_body (loop);
-
- invariant_regs = INITIALIZE_REG_SET (invariant_regs_head);
- single_set_regs = xmalloc (max_reg_num () * sizeof (rtx));
-
- blocks_invariant_registers (body, loop->num_nodes, invariant_regs);
- blocks_single_set_registers (body, loop->num_nodes, single_set_regs);
-
- n_branches = 0;
- for (i = 0; i < loop->num_nodes; i++)
- {
- for (e = body[i]->succ; e; e = e->succ_next)
- if (!flow_bb_inside_loop_p (loop, e->dest)
- && simple_loop_exit_p (loops, loop, e,
- invariant_regs, single_set_regs, &act))
- {
- /* Prefer constant iterations; the less the better. */
- if (!any)
- any = true;
- else if (!act.const_iter
- || (desc->const_iter && act.niter >= desc->niter))
- continue;
- *desc = act;
- }
-
- if (body[i]->succ && body[i]->succ->succ_next)
- n_branches++;
- }
- desc->n_branches = n_branches;
-
- if (rtl_dump_file && any)
- {
- fprintf (rtl_dump_file, "; Simple loop %i\n", loop->num);
- if (desc->postincr)
- fprintf (rtl_dump_file,
- "; does postincrement after loop exit condition\n");
-
- fprintf (rtl_dump_file, "; Induction variable:");
- print_simple_rtl (rtl_dump_file, desc->var);
- fputc ('\n', rtl_dump_file);
-
- fprintf (rtl_dump_file, "; Initial values:");
- print_simple_rtl (rtl_dump_file, desc->var_alts);
- fputc ('\n', rtl_dump_file);
-
- fprintf (rtl_dump_file, "; Stride:");
- print_simple_rtl (rtl_dump_file, desc->stride);
- fputc ('\n', rtl_dump_file);
-
- fprintf (rtl_dump_file, "; Compared with:");
- print_simple_rtl (rtl_dump_file, desc->lim);
- fputc ('\n', rtl_dump_file);
-
- fprintf (rtl_dump_file, "; Alternative values:");
- print_simple_rtl (rtl_dump_file, desc->lim_alts);
- fputc ('\n', rtl_dump_file);
-
- fprintf (rtl_dump_file, "; Exit condition:");
- if (desc->neg)
- fprintf (rtl_dump_file, "(negated)");
- fprintf (rtl_dump_file, "%s\n", GET_RTX_NAME (desc->cond));
-
- fprintf (rtl_dump_file, "; Number of branches:");
- fprintf (rtl_dump_file, "%d\n", desc->n_branches);
+/* Releases the memory occupied by G. */
- fputc ('\n', rtl_dump_file);
- }
+static void
+free_graph (struct graph *g)
+{
+ struct edge *e, *n;
+ int i;
- free (body);
- FREE_REG_SET (invariant_regs);
- free (single_set_regs);
- return any;
+ for (i = 0; i < g->n_vertices; i++)
+ for (e = g->vertices[i].succ; e; e = n)
+ {
+ n = e->succ_next;
+ free (e);
+ }
+ free (g->vertices);
+ free (g);
}
/* Marks blocks and edges that are part of non-recognized loops; i.e. we
Everything is a bit complicated due to fact we do not want to do this
for parts of cycles that only "pass" through some loop -- i.e. for
each cycle, we want to mark blocks that belong directly to innermost
- loop containing the whole cycle. */
+ loop containing the whole cycle.
+
+ LOOPS is the loop tree. */
+
+#define LOOP_REPR(LOOP) ((LOOP)->num + last_basic_block)
+#define BB_REPR(BB) ((BB)->index + 1)
+
void
mark_irreducible_loops (struct loops *loops)
{
- int *dfs_in, *closed, *mr, *mri, *n_edges, *stack;
- unsigned i;
- edge **edges, e;
- edge *estack;
basic_block act;
- int stack_top, tick, depth;
+ edge e;
+ edge_iterator ei;
+ int i, src, dest;
+ struct graph *g;
+ int *queue1 = xmalloc ((last_basic_block + loops->num) * sizeof (int));
+ int *queue2 = xmalloc ((last_basic_block + loops->num) * sizeof (int));
+ int nq, depth;
struct loop *cloop;
/* Reset the flags. */
FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
{
act->flags &= ~BB_IRREDUCIBLE_LOOP;
- for (e = act->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, act->succs)
e->flags &= ~EDGE_IRREDUCIBLE_LOOP;
}
- /* The first last_basic_block + 1 entries are for real blocks (including
- entry); then we have loops->num - 1 fake blocks for loops to that we
- assign edges leading from loops (fake loop 0 is not interesting). */
- dfs_in = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- closed = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- mr = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- mri = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- n_edges = xmalloc ((last_basic_block + loops->num) * sizeof (int));
- edges = xmalloc ((last_basic_block + loops->num) * sizeof (edge *));
- stack = xmalloc ((n_basic_blocks + loops->num) * sizeof (int));
- estack = xmalloc ((n_basic_blocks + loops->num) * sizeof (edge));
-
/* Create the edge lists. */
- for (i = 0; i < last_basic_block + loops->num; i++)
- n_edges[i] = 0;
+ g = new_graph (last_basic_block + loops->num);
+
FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
- for (e = act->succ; e; e = e->succ_next)
+ FOR_EACH_EDGE (e, ei, act->succs)
{
/* Ignore edges to exit. */
if (e->dest == EXIT_BLOCK_PTR)
continue;
+
/* And latch edges. */
if (e->dest->loop_father->header == e->dest
&& e->dest->loop_father->latch == act)
continue;
+
/* Edges inside a single loop should be left where they are. Edges
to subloop headers should lead to representative of the subloop,
- but from the same place. */
- if (act->loop_father == e->dest->loop_father
- || act->loop_father == e->dest->loop_father->outer)
- {
- n_edges[act->index + 1]++;
- continue;
- }
- /* Edges exiting loops remain. They should lead from representative
+ but from the same place.
+
+ Edges exiting loops should lead from representative
of the son of nearest common ancestor of the loops in that
act lays. */
- depth = find_common_loop (act->loop_father, e->dest->loop_father)->depth + 1;
- if (depth == act->loop_father->depth)
- cloop = act->loop_father;
- else
- cloop = act->loop_father->pred[depth];
- n_edges[cloop->num + last_basic_block]++;
- }
- for (i = 0; i < last_basic_block + loops->num; i++)
- {
- edges[i] = xmalloc (n_edges[i] * sizeof (edge));
- n_edges[i] = 0;
- }
+ src = BB_REPR (act);
+ dest = BB_REPR (e->dest);
- FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
- for (e = act->succ; e; e = e->succ_next)
- {
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
- if (e->dest->loop_father->header == e->dest
- && e->dest->loop_father->latch == act)
- continue;
- if (act->loop_father == e->dest->loop_father
- || act->loop_father == e->dest->loop_father->outer)
+ if (e->dest->loop_father->header == e->dest)
+ dest = LOOP_REPR (e->dest->loop_father);
+
+ if (!flow_bb_inside_loop_p (act->loop_father, e->dest))
{
- edges[act->index + 1][n_edges[act->index + 1]++] = e;
- continue;
+ depth = find_common_loop (act->loop_father,
+ e->dest->loop_father)->depth + 1;
+ if (depth == act->loop_father->depth)
+ cloop = act->loop_father;
+ else
+ cloop = act->loop_father->pred[depth];
+
+ src = LOOP_REPR (cloop);
}
- depth = find_common_loop (act->loop_father, e->dest->loop_father)->depth + 1;
- if (depth == act->loop_father->depth)
- cloop = act->loop_father;
- else
- cloop = act->loop_father->pred[depth];
- i = cloop->num + last_basic_block;
- edges[i][n_edges[i]++] = e;
+
+ add_edge (g, src, dest, e);
}
- /* Compute dfs numbering, starting from loop headers, and mark found
- loops.*/
- tick = 0;
- for (i = 0; i < last_basic_block + loops->num; i++)
+ /* Find the strongly connected components. Use the algorithm of Tarjan --
+ first determine the postorder dfs numbering in reversed graph, then
+ run the dfs on the original graph in the order given by decreasing
+ numbers assigned by the previous pass. */
+ nq = 0;
+ FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
{
- dfs_in[i] = -1;
- closed[i] = 0;
- mr[i] = last_basic_block + loops->num;
- mri[i] = -1;
+ queue1[nq++] = BB_REPR (act);
}
-
- stack_top = 0;
- for (i = 0; i < loops->num; i++)
+ for (i = 1; i < (int) loops->num; i++)
if (loops->parray[i])
- {
- stack[stack_top] = loops->parray[i]->header->index + 1;
- estack[stack_top] = NULL;
- stack_top++;
- }
-
- while (stack_top)
- {
- int idx, sidx;
+ queue1[nq++] = LOOP_REPR (loops->parray[i]);
+ dfs (g, queue1, nq, queue2, false);
+ for (i = 0; i < nq; i++)
+ queue1[i] = queue2[nq - i - 1];
+ dfs (g, queue1, nq, NULL, true);
- idx = stack[stack_top - 1];
- if (dfs_in[idx] < 0)
- dfs_in[idx] = tick++;
+ /* Mark the irreducible loops. */
+ for_each_edge (g, check_irred);
- while (n_edges[idx])
- {
- e = edges[idx][--n_edges[idx]];
- sidx = e->dest->loop_father->header == e->dest
- ? e->dest->loop_father->num + last_basic_block
- : e->dest->index + 1;
- if (closed[sidx])
- {
- if (!closed[mri[sidx]])
- {
- if (mr[sidx] < mr[idx])
- {
- mr[idx] = mr[sidx];
- mri[idx] = mri[sidx];
- }
-
- if (mr[sidx] <= dfs_in[idx])
- e->flags |= EDGE_IRREDUCIBLE_LOOP;
- }
- continue;
- }
- if (dfs_in[sidx] < 0)
- {
- stack[stack_top] = sidx;
- estack[stack_top] = e;
- stack_top++;
- goto next;
- }
- if (dfs_in[sidx] < mr[idx])
- {
- mr[idx] = dfs_in[sidx];
- mri[idx] = sidx;
- }
- e->flags |= EDGE_IRREDUCIBLE_LOOP;
- }
+ free_graph (g);
+ free (queue1);
+ free (queue2);
- /* Return back. */
- closed[idx] = 1;
- e = estack[stack_top - 1];
- stack_top--;
- if (e)
- {
- /* Propagate information back. */
- sidx = stack[stack_top - 1];
- if (mr[sidx] > mr[idx])
- {
- mr[sidx] = mr[idx];
- mri[sidx] = mri[idx];
- }
- if (mr[idx] <= dfs_in[sidx])
- e->flags |= EDGE_IRREDUCIBLE_LOOP;
- }
- /* Mark the block if relevant. */
- if (idx && idx <= last_basic_block && mr[idx] <= dfs_in[idx])
- BASIC_BLOCK (idx - 1)->flags |= BB_IRREDUCIBLE_LOOP;
-next:;
- }
-
- free (stack);
- free (estack);
- free (dfs_in);
- free (closed);
- free (mr);
- free (mri);
- for (i = 0; i < last_basic_block + loops->num; i++)
- free (edges[i]);
- free (edges);
- free (n_edges);
loops->state |= LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS;
}
{
bb = bbs[i];
ninsns++;
- for (insn = bb->head; insn != bb->end; insn = NEXT_INSN (insn))
+ for (insn = BB_HEAD (bb); insn != BB_END (bb); insn = NEXT_INSN (insn))
if (INSN_P (insn))
ninsns++;
}
bb = bbs[i];
binsns = 1;
- for (insn = bb->head; insn != bb->end; insn = NEXT_INSN (insn))
+ for (insn = BB_HEAD (bb); insn != BB_END (bb); insn = NEXT_INSN (insn))
if (INSN_P (insn))
binsns++;
expected_loop_iterations (const struct loop *loop)
{
edge e;
+ edge_iterator ei;
if (loop->header->count)
{
count_in = 0;
count_latch = 0;
- for (e = loop->header->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, loop->header->preds)
if (e->src == loop->latch)
count_latch = e->count;
else
count_in += e->count;
if (count_in == 0)
- return 0;
-
- expected = (count_latch + count_in - 1) / count_in;
+ expected = count_latch * 2;
+ else
+ expected = (count_latch + count_in - 1) / count_in;
/* Avoid overflows. */
return (expected > REG_BR_PROB_BASE ? REG_BR_PROB_BASE : expected);
freq_in = 0;
freq_latch = 0;
- for (e = loop->header->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, loop->header->preds)
if (e->src == loop->latch)
freq_latch = EDGE_FREQUENCY (e);
else
freq_in += EDGE_FREQUENCY (e);
if (freq_in == 0)
- return 0;
+ return freq_latch * 2;
return (freq_latch + freq_in - 1) / freq_in;
}
}
+
+/* Returns the maximum level of nesting of subloops of LOOP. */
+
+unsigned
+get_loop_level (const struct loop *loop)
+{
+ const struct loop *ploop;
+ unsigned mx = 0, l;
+
+ for (ploop = loop->inner; ploop; ploop = ploop->next)
+ {
+ l = get_loop_level (ploop);
+ if (l >= mx)
+ mx = l + 1;
+ }
+ return mx;
+}
+
+/* Returns estimate on cost of computing SEQ. */
+
+static unsigned
+seq_cost (rtx seq)
+{
+ unsigned cost = 0;
+ rtx set;
+
+ for (; seq; seq = NEXT_INSN (seq))
+ {
+ set = single_set (seq);
+ if (set)
+ cost += rtx_cost (set, SET);
+ else
+ cost++;
+ }
+
+ return cost;
+}
+
+/* The properties of the target. */
+
+unsigned target_avail_regs; /* Number of available registers. */
+unsigned target_res_regs; /* Number of reserved registers. */
+unsigned target_small_cost; /* The cost for register when there is a free one. */
+unsigned target_pres_cost; /* The cost for register when there are not too many
+ free ones. */
+unsigned target_spill_cost; /* The cost for register when we need to spill. */
+
+/* Initialize the constants for computing set costs. */
+
+void
+init_set_costs (void)
+{
+ rtx seq;
+ rtx reg1 = gen_raw_REG (SImode, FIRST_PSEUDO_REGISTER);
+ rtx reg2 = gen_raw_REG (SImode, FIRST_PSEUDO_REGISTER + 1);
+ rtx addr = gen_raw_REG (Pmode, FIRST_PSEUDO_REGISTER + 2);
+ rtx mem = validize_mem (gen_rtx_MEM (SImode, addr));
+ unsigned i;
+
+ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+ if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i)
+ && !fixed_regs[i])
+ target_avail_regs++;
+
+ target_res_regs = 3;
+
+ /* These are really just heuristic values. */
+
+ start_sequence ();
+ emit_move_insn (reg1, reg2);
+ seq = get_insns ();
+ end_sequence ();
+ target_small_cost = seq_cost (seq);
+ target_pres_cost = 2 * target_small_cost;
+
+ start_sequence ();
+ emit_move_insn (mem, reg1);
+ emit_move_insn (reg2, mem);
+ seq = get_insns ();
+ end_sequence ();
+ target_spill_cost = seq_cost (seq);
+}
+
+/* Calculates cost for having SIZE new loop global variables. REGS_USED is the
+ number of global registers used in loop. N_USES is the number of relevant
+ variable uses. */
+
+unsigned
+global_cost_for_size (unsigned size, unsigned regs_used, unsigned n_uses)
+{
+ unsigned regs_needed = regs_used + size;
+ unsigned cost = 0;
+
+ if (regs_needed + target_res_regs <= target_avail_regs)
+ cost += target_small_cost * size;
+ else if (regs_needed <= target_avail_regs)
+ cost += target_pres_cost * size;
+ else
+ {
+ cost += target_pres_cost * size;
+ cost += target_spill_cost * n_uses * (regs_needed - target_avail_regs) / regs_needed;
+ }
+
+ return cost;
+}
+
+/* Sets EDGE_LOOP_EXIT flag for all exits of LOOPS. */
+
+void
+mark_loop_exit_edges (struct loops *loops)
+{
+ basic_block bb;
+ edge e;
+
+ if (loops->num <= 1)
+ return;
+
+ FOR_EACH_BB (bb)
+ {
+ edge_iterator ei;
+
+ /* Do not mark exits from the fake outermost loop. */
+ if (!bb->loop_father->outer)
+ continue;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if (loop_exit_edge_p (bb->loop_father, e))
+ e->flags |= EDGE_LOOP_EXIT;
+ else
+ e->flags &= ~EDGE_LOOP_EXIT;
+ }
+ }
+}
+
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