\f
/* An obstack for our working variables. */
-static struct obstack gcse_obstack;
-
-struct reg_use {rtx reg_rtx; };
-
-/* Hash table of expressions. */
-
-struct expr
-{
- /* The expression (SET_SRC for expressions, PATTERN for assignments). */
- rtx expr;
- /* Index in the available expression bitmaps. */
- int bitmap_index;
- /* Next entry with the same hash. */
- struct expr *next_same_hash;
- /* List of available occurrence in basic blocks in the function.
- An "available occurrence" is one that is the last occurrence in the
- basic block and the operands are not modified by following statements in
- the basic block [including this insn]. */
- struct occr *avail_occr;
-};
+static struct obstack cprop_obstack;
/* Occurrence of an expression.
There is one per basic block. If a pattern appears more than once the
DEF_VEC_P (occr_t);
DEF_VEC_ALLOC_P (occr_t, heap);
-/* Expression and copy propagation hash tables.
+/* Hash table entry for assignment expressions. */
+
+struct expr
+{
+ /* The expression (DEST := SRC). */
+ rtx dest;
+ rtx src;
+
+ /* Index in the available expression bitmaps. */
+ int bitmap_index;
+ /* Next entry with the same hash. */
+ struct expr *next_same_hash;
+ /* List of available occurrence in basic blocks in the function.
+ An "available occurrence" is one that is the last occurrence in the
+ basic block and whose operands are not modified by following statements
+ in the basic block [including this insn]. */
+ struct occr *avail_occr;
+};
+
+/* Hash table for copy propagation expressions.
Each hash table is an array of buckets.
??? It is known that if it were an array of entries, structure elements
`next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
/* Array of implicit set patterns indexed by basic block index. */
static rtx *implicit_sets;
+/* Array of indexes of expressions for implicit set patterns indexed by basic
+ block index. In other words, implicit_set_indexes[i] is the bitmap_index
+ of the expression whose RTX is implicit_sets[i]. */
+static int *implicit_set_indexes;
+
/* Bitmap containing one bit for each register in the program.
Used when performing GCSE to track which registers have been set since
the start or end of the basic block while traversing that block. */
static int global_const_prop_count;
/* Number of global copies propagated. */
static int global_copy_prop_count;
-\f
-
-#define GNEW(T) ((T *) gmalloc (sizeof (T)))
-
-#define GNEWVEC(T, N) ((T *) gmalloc (sizeof (T) * (N)))
-#define GNEWVAR(T, S) ((T *) gmalloc ((S)))
-
-#define GOBNEW(T) ((T *) gcse_alloc (sizeof (T)))
-#define GOBNEWVAR(T, S) ((T *) gcse_alloc ((S)))
-\f
-/* Cover function to xmalloc to record bytes allocated. */
-
-static void *
-gmalloc (size_t size)
-{
- bytes_used += size;
- return xmalloc (size);
-}
+#define GOBNEW(T) ((T *) cprop_alloc (sizeof (T)))
+#define GOBNEWVAR(T, S) ((T *) cprop_alloc ((S)))
/* Cover function to obstack_alloc. */
static void *
-gcse_alloc (unsigned long size)
+cprop_alloc (unsigned long size)
{
bytes_used += size;
- return obstack_alloc (&gcse_obstack, size);
-}
-
-/* Allocate memory for the reg/memory set tracking tables.
- This is called at the start of each pass. */
-
-static void
-alloc_gcse_mem (void)
-{
- /* Allocate vars to track sets of regs. */
- reg_set_bitmap = ALLOC_REG_SET (NULL);
-}
-
-/* Free memory allocated by alloc_gcse_mem. */
-
-static void
-free_gcse_mem (void)
-{
- FREE_REG_SET (reg_set_bitmap);
+ return obstack_alloc (&cprop_obstack, size);
}
\f
/* Return nonzero if register X is unchanged from INSN to the end
return hash % hash_table_size;
}
-/* Return nonzero if exp1 is equivalent to exp2. */
-
-static int
-expr_equiv_p (const_rtx x, const_rtx y)
-{
- return exp_equiv_p (x, y, 0, true);
-}
-
-/* Insert pattern X in INSN in the hash table.
- X is a SET of a reg to either another reg or a constant.
- If it is already present, record it as the last occurrence in INSN's
- basic block. */
+/* Insert assignment DEST:=SET from INSN in the hash table.
+ DEST is a register and SET is a register or a suitable constant.
+ If the assignment is already present in the table, record it as
+ the last occurrence in INSN's basic block.
+ IMPLICIT is true if it's an implicit set, false otherwise. */
static void
-insert_set_in_table (rtx x, rtx insn, struct hash_table_d *table)
+insert_set_in_table (rtx dest, rtx src, rtx insn, struct hash_table_d *table,
+ bool implicit)
{
- int found;
+ bool found = false;
unsigned int hash;
struct expr *cur_expr, *last_expr = NULL;
struct occr *cur_occr;
- gcc_assert (GET_CODE (x) == SET && REG_P (SET_DEST (x)));
+ hash = hash_set (REGNO (dest), table->size);
- hash = hash_set (REGNO (SET_DEST (x)), table->size);
-
- cur_expr = table->table[hash];
- found = 0;
-
- while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
+ for (cur_expr = table->table[hash]; cur_expr;
+ cur_expr = cur_expr->next_same_hash)
{
- /* If the expression isn't found, save a pointer to the end of
- the list. */
+ if (dest == cur_expr->dest
+ && src == cur_expr->src)
+ {
+ found = true;
+ break;
+ }
last_expr = cur_expr;
- cur_expr = cur_expr->next_same_hash;
}
if (! found)
/* Set the fields of the expr element.
We must copy X because it can be modified when copy propagation is
performed on its operands. */
- cur_expr->expr = copy_rtx (x);
+ cur_expr->dest = copy_rtx (dest);
+ cur_expr->src = copy_rtx (src);
cur_expr->bitmap_index = table->n_elems++;
cur_expr->next_same_hash = NULL;
cur_expr->avail_occr = NULL;
cur_occr->next = cur_expr->avail_occr;
cur_expr->avail_occr = cur_occr;
}
+
+ /* Record bitmap_index of the implicit set in implicit_set_indexes. */
+ if (implicit)
+ implicit_set_indexes[BLOCK_FOR_INSN(insn)->index] = cur_expr->bitmap_index;
}
/* Determine whether the rtx X should be treated as a constant for CPROP.
is sharable. */
static bool
-gcse_constant_p (const_rtx x)
+cprop_constant_p (const_rtx x)
{
return CONSTANT_P (x) && (GET_CODE (x) != CONST || shared_const_p (x));
}
-/* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
- expression one). */
+/* Scan SET present in INSN and add an entry to the hash TABLE.
+ IMPLICIT is true if it's an implicit set, false otherwise. */
static void
-hash_scan_set (rtx pat, rtx insn, struct hash_table_d *table)
+hash_scan_set (rtx set, rtx insn, struct hash_table_d *table, bool implicit)
{
- rtx src = SET_SRC (pat);
- rtx dest = SET_DEST (pat);
+ rtx src = SET_SRC (set);
+ rtx dest = SET_DEST (set);
if (REG_P (dest)
&& ! HARD_REGISTER_P (dest)
for INSN, we miss copy propagation opportunities.
Note that this does not impede profitable constant propagations. We
- "look through" reg-reg sets in lookup_avail_set. */
+ "look through" reg-reg sets in lookup_set. */
rtx note = find_reg_equal_equiv_note (insn);
if (note != 0
&& REG_NOTE_KIND (note) == REG_EQUAL
&& !REG_P (src)
- && gcse_constant_p (XEXP (note, 0)))
- src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
+ && cprop_constant_p (XEXP (note, 0)))
+ src = XEXP (note, 0), set = gen_rtx_SET (VOIDmode, dest, src);
/* Record sets for constant/copy propagation. */
if ((REG_P (src)
&& src != dest
&& ! HARD_REGISTER_P (src)
&& reg_available_p (src, insn))
- || gcse_constant_p (src))
- insert_set_in_table (pat, insn, table);
+ || cprop_constant_p (src))
+ insert_set_in_table (dest, src, insn, table, implicit);
}
}
-/* Process INSN and add hash table entries as appropriate.
-
- Only available expressions that set a single pseudo-reg are recorded.
-
- Single sets in a PARALLEL could be handled, but it's an extra complication
- that isn't dealt with right now. The trick is handling the CLOBBERs that
- are also in the PARALLEL. Later.
-
- If SET_P is nonzero, this is for the assignment hash table,
- otherwise it is for the expression hash table. */
+/* Process INSN and add hash table entries as appropriate. */
static void
hash_scan_insn (rtx insn, struct hash_table_d *table)
what's been modified. */
if (GET_CODE (pat) == SET)
- hash_scan_set (pat, insn, table);
+ hash_scan_set (pat, insn, table, false);
else if (GET_CODE (pat) == PARALLEL)
for (i = 0; i < XVECLEN (pat, 0); i++)
{
rtx x = XVECEXP (pat, 0, i);
if (GET_CODE (x) == SET)
- hash_scan_set (x, insn, table);
+ hash_scan_set (x, insn, table, false);
}
}
+/* Dump the hash table TABLE to file FILE under the name NAME. */
+
static void
dump_hash_table (FILE *file, const char *name, struct hash_table_d *table)
{
expr = flat_table[i];
fprintf (file, "Index %d (hash value %d)\n ",
expr->bitmap_index, hash_val[i]);
- print_rtl (file, expr->expr);
+ print_rtl (file, expr->dest);
+ fprintf (file, " := ");
+ print_rtl (file, expr->src);
fprintf (file, "\n");
}
}
/* Record as unavailable all registers that are DEF operands of INSN. */
+
static void
make_set_regs_unavailable (rtx insn)
{
SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (*def_rec));
}
-/* Top level function to create an assignments hash table.
+/* Top level function to create an assignment hash table.
Assignment entries are placed in the hash table if
- they are of the form (set (pseudo-reg) src),
{
basic_block bb;
+ /* Allocate vars to track sets of regs. */
+ reg_set_bitmap = ALLOC_REG_SET (NULL);
+
FOR_EACH_BB (bb)
{
rtx insn;
/* Insert implicit sets in the hash table, pretending they appear as
insns at the head of the basic block. */
if (implicit_sets[bb->index] != NULL_RTX)
- hash_scan_set (implicit_sets[bb->index], BB_HEAD (bb), table);
+ hash_scan_set (implicit_sets[bb->index], BB_HEAD (bb), table, true);
}
+
+ FREE_REG_SET (reg_set_bitmap);
}
/* Allocate space for the set/expr hash TABLE.
??? Later take some measurements. */
table->size |= 1;
n = table->size * sizeof (struct expr *);
- table->table = GNEWVAR (struct expr *, n);
+ table->table = XNEWVAR (struct expr *, n);
}
/* Free things allocated by alloc_hash_table. */
expr = table->table[hash];
- while (expr && REGNO (SET_DEST (expr->expr)) != regno)
+ while (expr && REGNO (expr->dest) != regno)
expr = expr->next_same_hash;
return expr;
{
do
expr = expr->next_same_hash;
- while (expr && REGNO (SET_DEST (expr->expr)) != regno);
+ while (expr && REGNO (expr->dest) != regno);
return expr;
}
for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++)
SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (*def_rec));
}
-
\f
/* Compute copy/constant propagation working variables. */
/* Local properties of assignments. */
-static sbitmap *cprop_pavloc;
-static sbitmap *cprop_absaltered;
+static sbitmap *cprop_avloc;
+static sbitmap *cprop_kill;
/* Global properties of assignments (computed from the local properties). */
static sbitmap *cprop_avin;
static void
alloc_cprop_mem (int n_blocks, int n_sets)
{
- cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
- cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
+ cprop_avloc = sbitmap_vector_alloc (n_blocks, n_sets);
+ cprop_kill = sbitmap_vector_alloc (n_blocks, n_sets);
cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
static void
free_cprop_mem (void)
{
- sbitmap_vector_free (cprop_pavloc);
- sbitmap_vector_free (cprop_absaltered);
+ sbitmap_vector_free (cprop_avloc);
+ sbitmap_vector_free (cprop_kill);
sbitmap_vector_free (cprop_avin);
sbitmap_vector_free (cprop_avout);
}
-/* For each block, compute whether X is transparent. X is either an
- expression or an assignment [though we don't care which, for this context
- an assignment is treated as an expression]. For each block where an
- element of X is modified, set the INDX bit in BMAP. */
-
-static void
-compute_transp (const_rtx x, int indx, sbitmap *bmap)
-{
- int i, j;
- enum rtx_code code;
- const char *fmt;
-
- /* repeat is used to turn tail-recursion into iteration since GCC
- can't do it when there's no return value. */
- repeat:
-
- if (x == 0)
- return;
-
- code = GET_CODE (x);
- switch (code)
- {
- case REG:
- {
- df_ref def;
- for (def = DF_REG_DEF_CHAIN (REGNO (x));
- def;
- def = DF_REF_NEXT_REG (def))
- SET_BIT (bmap[DF_REF_BB (def)->index], indx);
- }
- return;
-
- case PC:
- case CC0: /*FIXME*/
- case CONST:
- case CONST_INT:
- case CONST_DOUBLE:
- case CONST_FIXED:
- case CONST_VECTOR:
- case SYMBOL_REF:
- case LABEL_REF:
- case ADDR_VEC:
- case ADDR_DIFF_VEC:
- return;
-
- default:
- break;
- }
-
- for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
- {
- if (fmt[i] == 'e')
- {
- /* If we are about to do the last recursive call
- needed at this level, change it into iteration.
- This function is called enough to be worth it. */
- if (i == 0)
- {
- x = XEXP (x, i);
- goto repeat;
- }
-
- compute_transp (XEXP (x, i), indx, bmap);
- }
- else if (fmt[i] == 'E')
- for (j = 0; j < XVECLEN (x, i); j++)
- compute_transp (XVECEXP (x, i, j), indx, bmap);
- }
-}
-
/* Compute the local properties of each recorded expression.
Local properties are those that are defined by the block, irrespective of
other blocks.
- An expression is transparent in a block if its operands are not modified
- in the block.
+ An expression is killed in a block if its operands, either DEST or SRC, are
+ modified in the block.
An expression is computed (locally available) in a block if it is computed
at least once and expression would contain the same value if the
computation was moved to the end of the block.
- TRANSP and COMP are destination sbitmaps for recording local properties.
- If NULL, then it is not necessary to compute or record that particular
- property.
-
- TRANSP is computed as ~TRANSP, since this is really cprop's ABSALTERED. */
+ KILL and COMP are destination sbitmaps for recording local properties. */
static void
-compute_local_properties (sbitmap *transp, sbitmap *comp,
+compute_local_properties (sbitmap *kill, sbitmap *comp,
struct hash_table_d *table)
{
unsigned int i;
- /* Initialize any bitmaps that were passed in. */
- if (transp)
- {
- sbitmap_vector_zero (transp, last_basic_block);
- }
-
- if (comp)
- sbitmap_vector_zero (comp, last_basic_block);
+ /* Initialize the bitmaps that were passed in. */
+ sbitmap_vector_zero (kill, last_basic_block);
+ sbitmap_vector_zero (comp, last_basic_block);
for (i = 0; i < table->size; i++)
{
for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
{
int indx = expr->bitmap_index;
+ df_ref def;
struct occr *occr;
- /* The expression is transparent in this block if it is not killed.
- We start by assuming all are transparent [none are killed], and
- then reset the bits for those that are. */
- if (transp)
- compute_transp (expr->expr, indx, transp);
+ /* For each definition of the destination pseudo-reg, the expression
+ is killed in the block where the definition is. */
+ for (def = DF_REG_DEF_CHAIN (REGNO (expr->dest));
+ def; def = DF_REF_NEXT_REG (def))
+ SET_BIT (kill[DF_REF_BB (def)->index], indx);
+
+ /* If the source is a pseudo-reg, for each definition of the source,
+ the expression is killed in the block where the definition is. */
+ if (REG_P (expr->src))
+ for (def = DF_REG_DEF_CHAIN (REGNO (expr->src));
+ def; def = DF_REF_NEXT_REG (def))
+ SET_BIT (kill[DF_REF_BB (def)->index], indx);
/* The occurrences recorded in avail_occr are exactly those that
- we want to set to nonzero in COMP. */
- if (comp)
- for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
- {
- SET_BIT (comp[BLOCK_FOR_INSN (occr->insn)->index], indx);
- }
+ are locally available in the block where they are. */
+ for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
+ {
+ SET_BIT (comp[BLOCK_FOR_INSN (occr->insn)->index], indx);
+ }
}
}
}
static void
compute_cprop_data (void)
{
- compute_local_properties (cprop_absaltered, cprop_pavloc, &set_hash_table);
- compute_available (cprop_pavloc, cprop_absaltered,
- cprop_avout, cprop_avin);
+ basic_block bb;
+
+ compute_local_properties (cprop_kill, cprop_avloc, &set_hash_table);
+ compute_available (cprop_avloc, cprop_kill, cprop_avout, cprop_avin);
+
+ /* Merge implicit sets into CPROP_AVIN. They are always available at the
+ entry of their basic block. We need to do this because 1) implicit sets
+ aren't recorded for the local pass so they cannot be propagated within
+ their basic block by this pass and 2) the global pass would otherwise
+ propagate them only in the successors of their basic block. */
+ FOR_EACH_BB (bb)
+ {
+ int index = implicit_set_indexes[bb->index];
+ if (index != -1)
+ SET_BIT (cprop_avin[bb->index], index);
+ }
}
\f
/* Copy/constant propagation. */
/* Maximum number of register uses in an insn that we handle. */
#define MAX_USES 8
-/* Table of uses found in an insn.
+/* Table of uses (registers, both hard and pseudo) found in an insn.
Allocated statically to avoid alloc/free complexity and overhead. */
-static struct reg_use reg_use_table[MAX_USES];
+static rtx reg_use_table[MAX_USES];
/* Index into `reg_use_table' while building it. */
-static int reg_use_count;
+static unsigned reg_use_count;
/* Set up a list of register numbers used in INSN. The found uses are stored
in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
if (reg_use_count == MAX_USES)
return;
- reg_use_table[reg_use_count].reg_rtx = x;
+ reg_use_table[reg_use_count] = x;
reg_use_count++;
}
}
}
-/* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
- Returns nonzero is successful. */
+/* Try to replace all uses of FROM in INSN with TO.
+ Return nonzero if successful. */
static int
try_replace_reg (rtx from, rtx to, rtx insn)
simplify_replace_rtx (XEXP (note, 0), from, to));
if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
{
- /* If above failed and this is a single set, try to simplify the source of
- the set given our substitution. We could perhaps try this for multiple
- SETs, but it probably won't buy us anything. */
+ /* If above failed and this is a single set, try to simplify the source
+ of the set given our substitution. We could perhaps try this for
+ multiple SETs, but it probably won't buy us anything. */
src = simplify_replace_rtx (SET_SRC (set), from, to);
if (!rtx_equal_p (src, SET_SRC (set))
note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
}
+ if (set && MEM_P (SET_DEST (set)) && reg_mentioned_p (from, SET_DEST (set)))
+ {
+ /* Registers can also appear as uses in SET_DEST if it is a MEM.
+ We could perhaps try this for multiple SETs, but it probably
+ won't buy us anything. */
+ rtx dest = simplify_replace_rtx (SET_DEST (set), from, to);
+
+ if (!rtx_equal_p (dest, SET_DEST (set))
+ && validate_change (insn, &SET_DEST (set), dest, 0))
+ success = 1;
+ }
+
/* REG_EQUAL may get simplified into register.
We don't allow that. Remove that note. This code ought
not to happen, because previous code ought to synthesize
return success;
}
-/* Find a set of REGNOs that are available on entry to INSN's block. Returns
+/* Find a set of REGNOs that are available on entry to INSN's block. Return
NULL no such set is found. */
static struct expr *
if (set == 0)
break;
- gcc_assert (GET_CODE (set->expr) == SET);
-
- src = SET_SRC (set->expr);
+ src = set->src;
/* We know the set is available.
Now check that SRC is locally anticipatable (i.e. none of the
If the source operand changed, we may still use it for the next
iteration of this loop, but we may not use it for substitutions. */
- if (gcse_constant_p (src) || reg_not_set_p (src, insn))
+ if (cprop_constant_p (src) || reg_not_set_p (src, insn))
set1 = set;
/* If the source of the set is anything except a register, then
JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
it is the instruction that immediately precedes JUMP, and must be a
single SET of a register. FROM is what we will try to replace,
- SRC is the constant we will try to substitute for it. Returns nonzero
+ SRC is the constant we will try to substitute for it. Return nonzero
if a change was made. */
static int
if (dump_file != NULL)
{
fprintf (dump_file,
- "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
- REGNO (from), INSN_UID (jump));
+ "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with"
+ "constant ", REGNO (from), INSN_UID (jump));
print_rtl (dump_file, src);
fprintf (dump_file, "\n");
}
return 1;
}
-static bool
-constprop_register (rtx insn, rtx from, rtx to)
+/* Subroutine of cprop_insn that tries to propagate constants. FROM is what
+ we will try to replace, SRC is the constant we will try to substitute for
+ it and INSN is the instruction where this will be happening. */
+
+static int
+constprop_register (rtx from, rtx src, rtx insn)
{
rtx sset;
{
rtx dest = SET_DEST (sset);
if ((REG_P (dest) || CC0_P (dest))
- && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
+ && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn),
+ from, src))
return 1;
}
/* Handle normal insns next. */
- if (NONJUMP_INSN_P (insn)
- && try_replace_reg (from, to, insn))
+ if (NONJUMP_INSN_P (insn) && try_replace_reg (from, src, insn))
return 1;
/* Try to propagate a CONST_INT into a conditional jump.
Right now the insn in question must look like
(set (pc) (if_then_else ...)) */
else if (any_condjump_p (insn) && onlyjump_p (insn))
- return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
+ return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, src);
return 0;
}
/* Perform constant and copy propagation on INSN.
- The result is nonzero if a change was made. */
+ Return nonzero if a change was made. */
static int
cprop_insn (rtx insn)
{
- struct reg_use *reg_used;
- int changed = 0;
+ unsigned i;
+ int changed = 0, changed_this_round;
rtx note;
- if (!INSN_P (insn))
- return 0;
-
+retry:
+ changed_this_round = 0;
reg_use_count = 0;
note_uses (&PATTERN (insn), find_used_regs, NULL);
- note = find_reg_equal_equiv_note (insn);
-
/* We may win even when propagating constants into notes. */
+ note = find_reg_equal_equiv_note (insn);
if (note)
find_used_regs (&XEXP (note, 0), NULL);
- for (reg_used = ®_use_table[0]; reg_use_count > 0;
- reg_used++, reg_use_count--)
+ for (i = 0; i < reg_use_count; i++)
{
- unsigned int regno = REGNO (reg_used->reg_rtx);
- rtx pat, src;
+ rtx reg_used = reg_use_table[i];
+ unsigned int regno = REGNO (reg_used);
+ rtx src;
struct expr *set;
/* If the register has already been set in this block, there's
nothing we can do. */
- if (! reg_not_set_p (reg_used->reg_rtx, insn))
+ if (! reg_not_set_p (reg_used, insn))
continue;
/* Find an assignment that sets reg_used and is available
if (! set)
continue;
- pat = set->expr;
- /* ??? We might be able to handle PARALLELs. Later. */
- gcc_assert (GET_CODE (pat) == SET);
-
- src = SET_SRC (pat);
+ src = set->src;
/* Constant propagation. */
- if (gcse_constant_p (src))
+ if (cprop_constant_p (src))
{
- if (constprop_register (insn, reg_used->reg_rtx, src))
+ if (constprop_register (reg_used, src, insn))
{
- changed = 1;
+ changed_this_round = changed = 1;
global_const_prop_count++;
if (dump_file != NULL)
{
- fprintf (dump_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
- fprintf (dump_file, "insn %d with constant ", INSN_UID (insn));
+ fprintf (dump_file,
+ "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
+ fprintf (dump_file, "insn %d with constant ",
+ INSN_UID (insn));
print_rtl (dump_file, src);
fprintf (dump_file, "\n");
}
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
&& REGNO (src) != regno)
{
- if (try_replace_reg (reg_used->reg_rtx, src, insn))
+ if (try_replace_reg (reg_used, src, insn))
{
- changed = 1;
+ changed_this_round = changed = 1;
global_copy_prop_count++;
if (dump_file != NULL)
{
- fprintf (dump_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
+ fprintf (dump_file,
+ "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
regno, INSN_UID (insn));
fprintf (dump_file, " with reg %d\n", REGNO (src));
}
/* The original insn setting reg_used may or may not now be
- deletable. We leave the deletion to flow. */
+ deletable. We leave the deletion to DCE. */
/* FIXME: If it turns out that the insn isn't deletable,
then we may have unnecessarily extended register lifetimes
and made things worse. */
}
}
+
+ /* If try_replace_reg simplified the insn, the regs found
+ by find_used_regs may not be valid anymore. Start over. */
+ if (changed_this_round)
+ goto retry;
}
if (changed && DEBUG_INSN_P (insn))
rtx this_rtx = l->loc;
rtx note;
- if (gcse_constant_p (this_rtx))
+ if (cprop_constant_p (this_rtx))
newcnst = this_rtx;
if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
/* Don't copy propagate if it has attached REG_EQUIV note.
|| ! MEM_P (XEXP (note, 0))))
newreg = this_rtx;
}
- if (newcnst && constprop_register (insn, x, newcnst))
+ if (newcnst && constprop_register (x, newcnst, insn))
{
if (dump_file != NULL)
{
{
basic_block bb;
rtx insn;
- struct reg_use *reg_used;
bool changed = false;
+ unsigned i;
cselib_init (0);
FOR_EACH_BB (bb)
if (note)
local_cprop_find_used_regs (&XEXP (note, 0), NULL);
- for (reg_used = ®_use_table[0]; reg_use_count > 0;
- reg_used++, reg_use_count--)
+ for (i = 0; i < reg_use_count; i++)
{
- if (do_local_cprop (reg_used->reg_rtx, insn))
+ if (do_local_cprop (reg_use_table[i], insn))
{
- changed = true;
+ if (!DEBUG_INSN_P (insn))
+ changed = true;
break;
}
}
if (INSN_DELETED_P (insn))
break;
}
- while (reg_use_count);
+ while (i < reg_use_count);
}
cselib_process_insn (insn);
}
return get_condition (jump, NULL, false, true);
}
-/* Check the comparison COND to see if we can safely form an implicit set from
- it. COND is either an EQ or NE comparison. */
+/* Check the comparison COND to see if we can safely form an implicit
+ set from it. */
static bool
implicit_set_cond_p (const_rtx cond)
{
- const enum machine_mode mode = GET_MODE (XEXP (cond, 0));
- const_rtx cst = XEXP (cond, 1);
+ enum machine_mode mode;
+ rtx cst;
+
+ /* COND must be either an EQ or NE comparison. */
+ if (GET_CODE (cond) != EQ && GET_CODE (cond) != NE)
+ return false;
+
+ /* The first operand of COND must be a pseudo-reg. */
+ if (! REG_P (XEXP (cond, 0))
+ || HARD_REGISTER_P (XEXP (cond, 0)))
+ return false;
+
+ /* The second operand of COND must be a suitable constant. */
+ mode = GET_MODE (XEXP (cond, 0));
+ cst = XEXP (cond, 1);
/* We can't perform this optimization if either operand might be or might
contain a signed zero. */
return 0;
}
- return gcse_constant_p (cst);
+ return cprop_constant_p (cst);
}
/* Find the implicit sets of a function. An "implicit set" is a constraint
function records the set patterns that are implicit at the start of each
basic block.
- FIXME: This would be more effective if critical edges are pre-split. As
- it is now, we can't record implicit sets for blocks that have
- critical successor edges. This results in missed optimizations
- and in more (unnecessary) work in cfgcleanup.c:thread_jump(). */
+ If an implicit set is found but the set is implicit on a critical edge,
+ this critical edge is split.
-static void
+ Return true if the CFG was modified, false otherwise. */
+
+static bool
find_implicit_sets (void)
{
basic_block bb, dest;
- unsigned int count;
rtx cond, new_rtx;
+ unsigned int count = 0;
+ bool edges_split = false;
+ size_t implicit_sets_size = last_basic_block + 10;
+
+ implicit_sets = XCNEWVEC (rtx, implicit_sets_size);
- count = 0;
FOR_EACH_BB (bb)
- /* Check for more than one successor. */
- if (EDGE_COUNT (bb->succs) > 1)
- {
- cond = fis_get_condition (BB_END (bb));
+ {
+ /* Check for more than one successor. */
+ if (EDGE_COUNT (bb->succs) <= 1)
+ continue;
- if (cond
- && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
- && REG_P (XEXP (cond, 0))
- && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
- && implicit_set_cond_p (cond))
- {
- dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
- : FALLTHRU_EDGE (bb)->dest;
+ cond = fis_get_condition (BB_END (bb));
- if (dest
- /* Record nothing for a critical edge. */
- && single_pred_p (dest)
- && dest != EXIT_BLOCK_PTR)
- {
- new_rtx = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
- XEXP (cond, 1));
- implicit_sets[dest->index] = new_rtx;
- if (dump_file)
- {
- fprintf(dump_file, "Implicit set of reg %d in ",
- REGNO (XEXP (cond, 0)));
- fprintf(dump_file, "basic block %d\n", dest->index);
- }
- count++;
- }
- }
+ /* If no condition is found or if it isn't of a suitable form,
+ ignore it. */
+ if (! cond || ! implicit_set_cond_p (cond))
+ continue;
+
+ dest = GET_CODE (cond) == EQ
+ ? BRANCH_EDGE (bb)->dest : FALLTHRU_EDGE (bb)->dest;
+
+ /* If DEST doesn't go anywhere, ignore it. */
+ if (! dest || dest == EXIT_BLOCK_PTR)
+ continue;
+
+ /* We have found a suitable implicit set. Try to record it now as
+ a SET in DEST. If DEST has more than one predecessor, the edge
+ between BB and DEST is a critical edge and we must split it,
+ because we can only record one implicit set per DEST basic block. */
+ if (! single_pred_p (dest))
+ {
+ dest = split_edge (find_edge (bb, dest));
+ edges_split = true;
+ }
+
+ if (implicit_sets_size <= (size_t) dest->index)
+ {
+ size_t old_implicit_sets_size = implicit_sets_size;
+ implicit_sets_size *= 2;
+ implicit_sets = XRESIZEVEC (rtx, implicit_sets, implicit_sets_size);
+ memset (implicit_sets + old_implicit_sets_size, 0,
+ (implicit_sets_size - old_implicit_sets_size) * sizeof (rtx));
}
+ new_rtx = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
+ XEXP (cond, 1));
+ implicit_sets[dest->index] = new_rtx;
+ if (dump_file)
+ {
+ fprintf(dump_file, "Implicit set of reg %d in ",
+ REGNO (XEXP (cond, 0)));
+ fprintf(dump_file, "basic block %d\n", dest->index);
+ }
+ count++;
+ }
+
if (dump_file)
fprintf (dump_file, "Found %d implicit sets\n", count);
+
+ /* Confess our sins. */
+ return edges_split;
}
/* Bypass conditional jumps. */
static int bypass_last_basic_block;
/* Find a set of REGNO to a constant that is available at the end of basic
- block BB. Returns NULL if no such set is found. Based heavily upon
+ block BB. Return NULL if no such set is found. Based heavily upon
find_avail_set. */
static struct expr *
if (set == 0)
break;
- gcc_assert (GET_CODE (set->expr) == SET);
-
- src = SET_SRC (set->expr);
- if (gcse_constant_p (src))
+ src = set->src;
+ if (cprop_constant_p (src))
result = set;
if (! REG_P (src))
return result;
}
-
/* Subroutine of bypass_block that checks whether a pseudo is killed by
any of the instructions inserted on an edge. Jump bypassing places
condition code setters on CFG edges using insert_insn_on_edge. This
{
rtx insn, note;
edge e, edest;
- int i, change;
+ int change;
int may_be_loop_header;
unsigned removed_p;
+ unsigned i;
edge_iterator ei;
insn = (setcc != NULL) ? setcc : jump;
}
/* The irreducible loops created by redirecting of edges entering the
- loop from outside would decrease effectiveness of some of the following
- optimizations, so prevent this. */
+ loop from outside would decrease effectiveness of some of the
+ following optimizations, so prevent this. */
if (may_be_loop_header
&& !(e->flags & EDGE_DFS_BACK))
{
for (i = 0; i < reg_use_count; i++)
{
- struct reg_use *reg_used = ®_use_table[i];
- unsigned int regno = REGNO (reg_used->reg_rtx);
+ rtx reg_used = reg_use_table[i];
+ unsigned int regno = REGNO (reg_used);
basic_block dest, old_dest;
struct expr *set;
rtx src, new_rtx;
continue;
/* Check the data flow is valid after edge insertions. */
- if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
+ if (e->insns.r && reg_killed_on_edge (reg_used, e))
continue;
src = SET_SRC (pc_set (jump));
SET_DEST (PATTERN (setcc)),
SET_SRC (PATTERN (setcc)));
- new_rtx = simplify_replace_rtx (src, reg_used->reg_rtx,
- SET_SRC (set->expr));
+ new_rtx = simplify_replace_rtx (src, reg_used, set->src);
/* Jump bypassing may have already placed instructions on
edges of the CFG. We can't bypass an outgoing edge that
has instructions associated with it, as these insns won't
get executed if the incoming edge is redirected. */
-
if (new_rtx == pc_rtx)
{
edest = FALLTHRU_EDGE (bb);
/* Avoid unification of the edge with other edges from original
branch. We would end up emitting the instruction on "both"
edges. */
-
if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc)))
&& find_edge (e->src, dest))
dest = NULL;
fprintf (dump_file, "JUMP-BYPASS: Proved reg %d "
"in jump_insn %d equals constant ",
regno, INSN_UID (jump));
- print_rtl (dump_file, SET_SRC (set->expr));
+ print_rtl (dump_file, set->src);
fprintf (dump_file, "\nBypass edge from %d->%d to %d\n",
e->src->index, old_dest->index, dest->index);
}
/* Find basic blocks with more than one predecessor that only contain a
single conditional jump. If the result of the comparison is known at
compile-time from any incoming edge, redirect that edge to the
- appropriate target. Returns nonzero if a change was made.
+ appropriate target. Return nonzero if a change was made.
This function is now mis-named, because we also handle indirect jumps. */
return changed;
}
\f
-/* Return true if the graph is too expensive to optimize. PASS is the
+/* Return true if the graph is too expensive to optimize. PASS is the
optimization about to be performed. */
static bool
return false;
}
-
\f
/* Main function for the CPROP pass. */
static int
one_cprop_pass (void)
{
+ int i;
int changed = 0;
/* Return if there's nothing to do, or it is too expensive. */
global_copy_prop_count = local_copy_prop_count = 0;
bytes_used = 0;
- gcc_obstack_init (&gcse_obstack);
- alloc_gcse_mem ();
+ gcc_obstack_init (&cprop_obstack);
/* Do a local const/copy propagation pass first. The global pass
only handles global opportunities.
FIXME: The global analysis would not get into infinite loops if it
would use the DF solver (via df_simple_dataflow) instead of
the solver implemented in this file. */
- if (local_cprop_pass ())
- {
- delete_unreachable_blocks ();
- df_analyze ();
- }
+ changed |= local_cprop_pass ();
+ if (changed)
+ delete_unreachable_blocks ();
+
+ /* Determine implicit sets. This may change the CFG (split critical
+ edges if that exposes an implicit set).
+ Note that find_implicit_sets() does not rely on up-to-date DF caches
+ so that we do not have to re-run df_analyze() even if local CPROP
+ changed something.
+ ??? This could run earlier so that any uncovered implicit sets
+ sets could be exploited in local_cprop_pass() also. Later. */
+ changed |= find_implicit_sets ();
+
+ /* If local_cprop_pass() or find_implicit_sets() changed something,
+ run df_analyze() to bring all insn caches up-to-date, and to take
+ new basic blocks from edge splitting on the DF radar.
+ NB: This also runs the fast DCE pass, because execute_rtl_cprop
+ sets DF_LR_RUN_DCE. */
+ if (changed)
+ df_analyze ();
- /* Determine implicit sets. */
- implicit_sets = XCNEWVEC (rtx, last_basic_block);
- find_implicit_sets ();
+ /* Initialize implicit_set_indexes array. */
+ implicit_set_indexes = XNEWVEC (int, last_basic_block);
+ for (i = 0; i < last_basic_block; i++)
+ implicit_set_indexes[i] = -1;
alloc_hash_table (&set_hash_table);
compute_hash_table (&set_hash_table);
alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
compute_cprop_data ();
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
+ free (implicit_set_indexes);
+ implicit_set_indexes = NULL;
+
+ /* Allocate vars to track sets of regs. */
+ reg_set_bitmap = ALLOC_REG_SET (NULL);
+
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR,
+ next_bb)
{
/* Reset tables used to keep track of what's still valid [since
the start of the block]. */
/* Keep track of everything modified by this insn. */
/* ??? Need to be careful w.r.t. mods done to INSN.
Don't call mark_oprs_set if we turned the
- insn into a NOTE. */
- if (! NOTE_P (insn))
+ insn into a NOTE, or deleted the insn. */
+ if (! NOTE_P (insn) && ! INSN_DELETED_P (insn))
mark_oprs_set (insn);
}
}
changed |= bypass_conditional_jumps ();
+
+ FREE_REG_SET (reg_set_bitmap);
free_cprop_mem ();
}
+ else
+ {
+ free (implicit_set_indexes);
+ implicit_set_indexes = NULL;
+ }
free_hash_table (&set_hash_table);
- free_gcse_mem ();
- obstack_free (&gcse_obstack, NULL);
+ obstack_free (&cprop_obstack, NULL);
if (dump_file)
{
return changed;
}
-
\f
/* All the passes implemented in this file. Each pass has its
own gate and execute function, and at the end of the file a
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_df_finish | TODO_verify_rtl_sharing |
- TODO_dump_func |
TODO_verify_flow | TODO_ggc_collect /* todo_flags_finish */
}
};
-
OSDN Git Service
