#include "toplev.h"
#include "target.h"
#include "rtlhooks-def.h"
+/* Include output.h for dump_file. */
+#include "output.h"
/* Number of attempts to combine instructions in this function. */
those blocks as starting points. */
static sbitmap refresh_blocks;
\f
+/* The following array records the combine_insn_cost for every insn
+ in the instruction stream. */
+
+static int *uid_insn_cost;
+
+/* Length of the currently allocated uid_insn_cost array. */
+
+static int last_insn_cost;
+
/* Incremented for each label. */
static int label_tick;
#define SUBST_INT(INTO, NEWVAL) do_SUBST_INT(&(INTO), (NEWVAL))
\f
+/* Calculate the rtx_cost of a single instruction. A return value of zero
+ indicates an instruction without a known cost. */
+
+static int
+combine_insn_cost (rtx pat)
+{
+ int i, cost;
+ rtx set;
+
+ /* Extract the single set rtx from the instruction pattern.
+ We can't use single_set since we only have the pattern. */
+ if (GET_CODE (pat) == SET)
+ set = pat;
+ else if (GET_CODE (pat) == PARALLEL)
+ {
+ set = NULL_RTX;
+ for (i = 0; i < XVECLEN (pat, 0); i++)
+ {
+ rtx x = XVECEXP (pat, 0, i);
+ if (GET_CODE (x) == SET)
+ {
+ if (set)
+ return 0;
+ set = x;
+ }
+ }
+ if (!set)
+ return 0;
+ }
+ else
+ return 0;
+
+ cost = rtx_cost (SET_SRC (set), SET);
+ return cost > 0 ? cost : COSTS_N_INSNS (1);
+}
+
+/* Subroutine of try_combine. Determine whether the combine replacement
+ patterns NEWPAT and NEWI2PAT are cheaper according to combine_insn_cost
+ that the original instruction sequence I1, I2 and I3. Note that I1
+ and/or NEWI2PAT may be NULL_RTX. This function returns false, if the
+ costs of all instructions can be estimated, and the replacements are
+ more expensive than the original sequence. */
+
+static bool
+combine_validate_cost (rtx i1, rtx i2, rtx i3, rtx newpat, rtx newi2pat)
+{
+ int i1_cost, i2_cost, i3_cost;
+ int new_i2_cost, new_i3_cost;
+ int old_cost, new_cost;
+
+ /* Lookup the original combine_insn_costs. */
+ i2_cost = INSN_UID (i2) <= last_insn_cost
+ ? uid_insn_cost[INSN_UID (i2)] : 0;
+ i3_cost = INSN_UID (i3) <= last_insn_cost
+ ? uid_insn_cost[INSN_UID (i3)] : 0;
+
+ if (i1)
+ {
+ i1_cost = INSN_UID (i1) <= last_insn_cost
+ ? uid_insn_cost[INSN_UID (i1)] : 0;
+ old_cost = (i1_cost > 0 && i2_cost > 0 && i3_cost > 0)
+ ? i1_cost + i2_cost + i3_cost : 0;
+ }
+ else
+ {
+ old_cost = (i2_cost > 0 && i3_cost > 0) ? i2_cost + i3_cost : 0;
+ i1_cost = 0;
+ }
+
+ /* Calculate the replacement combine_insn_costs. */
+ new_i3_cost = combine_insn_cost (newpat);
+ if (newi2pat)
+ {
+ new_i2_cost = combine_insn_cost (newi2pat);
+ new_cost = (new_i2_cost > 0 && new_i3_cost > 0)
+ ? new_i2_cost + new_i3_cost : 0;
+ }
+ else
+ {
+ new_cost = new_i3_cost;
+ new_i2_cost = 0;
+ }
+
+ /* Disallow this recombination if both new_cost and old_cost are
+ greater than zero, and new_cost is greater than old cost. */
+ if (!undobuf.other_insn
+ && old_cost > 0
+ && new_cost > old_cost)
+ {
+ if (dump_file)
+ {
+ if (i1)
+ {
+ fprintf (dump_file,
+ "rejecting combination of insns %d, %d and %d\n",
+ INSN_UID (i1), INSN_UID (i2), INSN_UID (i3));
+ fprintf (dump_file, "original costs %d + %d + %d = %d\n",
+ i1_cost, i2_cost, i3_cost, old_cost);
+ }
+ else
+ {
+ fprintf (dump_file,
+ "rejecting combination of insns %d and %d\n",
+ INSN_UID (i2), INSN_UID (i3));
+ fprintf (dump_file, "original costs %d + %d = %d\n",
+ i2_cost, i3_cost, old_cost);
+ }
+
+ if (newi2pat)
+ {
+ fprintf (dump_file, "replacement costs %d + %d = %d\n",
+ new_i2_cost, new_i3_cost, new_cost);
+ }
+ else
+ fprintf (dump_file, "replacement cost %d\n", new_cost);
+ }
+
+ return false;
+ }
+
+ /* Update the uid_insn_cost array with the replacement costs. */
+ uid_insn_cost[INSN_UID (i2)] = new_i2_cost;
+ uid_insn_cost[INSN_UID (i3)] = new_i3_cost;
+ if (i1)
+ uid_insn_cost[INSN_UID (i1)] = 0;
+
+ return true;
+}
+\f
/* Main entry point for combiner. F is the first insn of the function.
NREGS is the first unused pseudo-reg number.
refresh_blocks = sbitmap_alloc (last_basic_block);
sbitmap_zero (refresh_blocks);
+ /* Allocate array of current combine_insn_costs. */
+ uid_insn_cost = xcalloc (max_uid_cuid + 1, sizeof (int));
+ last_insn_cost = max_uid_cuid;
+
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
{
uid_cuid[INSN_UID (insn)] = ++i;
set_nonzero_bits_and_sign_copies (XEXP (links, 0), NULL_RTX,
NULL);
#endif
+
+ /* Record the current combine_insn_cost of this instruction. */
+ uid_insn_cost[INSN_UID (insn)] = combine_insn_cost (PATTERN (insn));
+ if (dump_file)
+ fprintf(dump_file, "insn_cost %d: %d\n",
+ INSN_UID (insn), uid_insn_cost[INSN_UID (insn)]);
}
if (GET_CODE (insn) == CODE_LABEL)
/* Clean up. */
sbitmap_free (refresh_blocks);
+ free (uid_insn_cost);
free (reg_stat);
free (uid_cuid);
}
#endif
+ /* Only allow this combination if combine_insn_costs reports that the
+ replacement instructions are cheaper than the originals. */
+ if (!combine_validate_cost (i1, i2, i3, newpat, newi2pat))
+ {
+ undo_all ();
+ return 0;
+ }
+
/* We now know that we can do this combination. Merge the insns and
update the status of registers and LOG_LINKS. */
projects / gcc.git / commitdiff