[rtl-optimization/117467] Mark FP destinations as dead

The next step in improving ext-dce is to clean up a minor wart in the
set/clobber handling code.

In that code the safe thing to do is to not process a destination at all.  That
will leave bits set in the live bitmaps for objects that may no longer be live.
Of course with extraneous bits set we use more memory and do more work managing
the bitmaps, but it's safe from a code correctness standpoint.

One case that is slipping through that we need to fix is scalar fp
destinations.  Essentially the code never tried to handle those and as a result
would leave those entities live and bubble them up through the CFG.

In the testcase at hand this takes us from ~10k live objects at entry to ~4k
live objects at entry.  Time spent in ext-dce goes from 2.14s to .64s.

Bootstrapped and regression tested on x86_64.

	PR rtl-optimization/117467
gcc/
	* ext-dce.cc (ext_dce_process_sets): Handle FP destinations better.

diff --git a/gcc/ext-dce.cc b/gcc/ext-dce.cc
index c53dd5b461617c726ac32f7b7b40008f708d8abf..35ddda00cdb639a6d9ad13afdf07b334a9cda77a 100644 (file)
--- a/gcc/ext-dce.cc
+++ b/gcc/ext-dce.cc
@@ -206,8 +206,8 @@ ext_dce_process_sets (rtx_insn *insn, rtx obj, bitmap live_tmp)
 
          /* We don't support vector destinations or destinations
             wider than DImode.  */
-         scalar_int_mode outer_mode;
-         if (!is_a <scalar_int_mode> (GET_MODE (x), &outer_mode)
+         scalar_mode outer_mode;
+         if (!is_a <scalar_mode> (GET_MODE (x), &outer_mode)
              || GET_MODE_BITSIZE (outer_mode) > HOST_BITS_PER_WIDE_INT)
            {
              /* Skip the subrtxs of this destination.  There is
@@ -239,7 +239,7 @@ ext_dce_process_sets (rtx_insn *insn, rtx obj, bitmap live_tmp)
              /* The inner mode might be larger, just punt for
                 that case.  Remember, we can not just continue to process
                 the inner RTXs due to the STRICT_LOW_PART.  */
-             if (!is_a <scalar_int_mode> (GET_MODE (SUBREG_REG (x)), &outer_mode)
+             if (!is_a <scalar_mode> (GET_MODE (SUBREG_REG (x)), &outer_mode)
                  || GET_MODE_BITSIZE (outer_mode) > HOST_BITS_PER_WIDE_INT)
                {
                  /* Skip the subrtxs of the STRICT_LOW_PART.  We can't
@@ -293,7 +293,7 @@ ext_dce_process_sets (rtx_insn *insn, rtx obj, bitmap live_tmp)
                 subreg and restart within the SET processing rather than
                 the top of the loop which just complicates the flow even
                 more.  */
-             if (!is_a <scalar_int_mode> (GET_MODE (SUBREG_REG (x)), &outer_mode)
+             if (!is_a <scalar_mode> (GET_MODE (SUBREG_REG (x)), &outer_mode)
                  || GET_MODE_BITSIZE (outer_mode) > HOST_BITS_PER_WIDE_INT)
                {
                  skipped_dest = true;