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[PATCH] combine: Print to dump if some insn cannot be combined into i3
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Segher Boessenkool <segher at kernel dot crashing dot org>
- Date: Wed, 29 Nov 2017 22:49:06 +0000
- Subject: [PATCH] combine: Print to dump if some insn cannot be combined into i3
- Authentication-results: sourceware.org; auth=none
Eventually we should print the reason that any combination fails.
This is a good start (these happen often).
Applying to trunk.
Segher
2017-11-29 Segher Boessenkool <segher@kernel.crashing.org>
* combine.c (try_combine): Print a message to dump file whenever
I0, I1, or I2 cannot be combined into I3.
---
gcc/combine.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/gcc/combine.c b/gcc/combine.c
index c578e47..22a382d 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3061,13 +3061,25 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
SUBST (PATTERN (i2), XVECEXP (PATTERN (i2), 0, 1));
}
- /* Verify that I2 and I1 are valid for combining. */
- if (! can_combine_p (i2, i3, i0, i1, NULL, NULL, &i2dest, &i2src)
- || (i1 && ! can_combine_p (i1, i3, i0, NULL, i2, NULL,
- &i1dest, &i1src))
- || (i0 && ! can_combine_p (i0, i3, NULL, NULL, i1, i2,
- &i0dest, &i0src)))
+ /* Verify that I2 and maybe I1 and I0 can be combined into I3. */
+ if (!can_combine_p (i2, i3, i0, i1, NULL, NULL, &i2dest, &i2src))
{
+ if (dump_file)
+ fprintf (dump_file, "Can't combine i2 into i3\n");
+ undo_all ();
+ return 0;
+ }
+ if (i1 && !can_combine_p (i1, i3, i0, NULL, i2, NULL, &i1dest, &i1src))
+ {
+ if (dump_file)
+ fprintf (dump_file, "Can't combine i1 into i3\n");
+ undo_all ();
+ return 0;
+ }
+ if (i0 && !can_combine_p (i0, i3, NULL, NULL, i1, i2, &i0dest, &i0src))
+ {
+ if (dump_file)
+ fprintf (dump_file, "Can't combine i0 into i3\n");
undo_all ();
return 0;
}
--
1.8.3.1