Hi!
The following testcase fails on ppc* due to invalid RTL sharing.
The problem is that replace_rtx never copy_rtx or copy_rtx_if_shared
anything, so if i{2,1,0}dest is present in CALL_INSN_FUNCTION_USAGE more
than once, and corresponding i{2,1,0}src is non-shareable RTL, then we ICE.
On the other side, copying whole CALL_INSN_FUNCTION_USAGE just in case, even
if we don't make any changes in there seems like a waste to me, furthermore,
I think the checking should make sure that CALL_INSN_FUNCTION_USAGE is never
shared between multiple instructions, so it shouldn't be a problem to modify
it in place. And lastly, if say i2dest appears in (plus i2dest const_int)
and i2src is (plus reg const_int), we don't simplify that into a single
plus.
The following patch should fix that, by not copying the EXPR_LIST nodes at
all, and just using simplify_replace_rtx which will not modify if no change
is needed, and will copy_rtx the src whenever a replacement is made.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-03-09 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/79909
* combine.c (try_combine): Use simplify_replace_rtx on individual
CALL_INSN_FUNCTION_USAGE elements instead of replace_rtx on copy_rtx
of the whole CALL_INSN_FUNCTION_USAGE.
* gcc.target/powerpc/pr79909.c: New test.
--- gcc/combine.c.jj 2017-02-13 16:39:09.000000000 +0100
+++ gcc/combine.c 2017-03-09 11:17:11.733117350 +0100
@@ -4293,26 +4293,25 @@ try_combine (rtx_insn *i3, rtx_insn *i2,
if (CALL_P (i3) && CALL_INSN_FUNCTION_USAGE (i3))
{
- rtx call_usage = CALL_INSN_FUNCTION_USAGE (i3);
-
- reset_used_flags (call_usage);
- call_usage = copy_rtx (call_usage);
-
- if (substed_i2)
+ for (rtx link = CALL_INSN_FUNCTION_USAGE (i3); link;
+ link = XEXP (link, 1))
{
- /* I2SRC must still be meaningful at this point. Some splitting
- operations can invalidate I2SRC, but those operations do not
- apply to calls. */
- gcc_assert (i2src);
- replace_rtx (call_usage, i2dest, i2src);
+ if (substed_i2)
+ {
+ /* I2SRC must still be meaningful at this point. Some
+ splitting operations can invalidate I2SRC, but those
+ operations do not apply to calls. */
+ gcc_assert (i2src);
+ XEXP (link, 0) = simplify_replace_rtx (XEXP (link, 0),
+ i2dest, i2src);
+ }
+ if (substed_i1)
+ XEXP (link, 0) = simplify_replace_rtx (XEXP (link, 0),
+ i1dest, i1src);
+ if (substed_i0)
+ XEXP (link, 0) = simplify_replace_rtx (XEXP (link, 0),
+ i0dest, i0src);
}
-
- if (substed_i1)
- replace_rtx (call_usage, i1dest, i1src);
- if (substed_i0)
- replace_rtx (call_usage, i0dest, i0src);
-
- CALL_INSN_FUNCTION_USAGE (i3) = call_usage;
}
if (undobuf.other_insn)
--- gcc/testsuite/gcc.target/powerpc/pr79909.c.jj 2017-03-09
11:46:06.088145481 +0100
+++ gcc/testsuite/gcc.target/powerpc/pr79909.c 2017-03-09 11:46:49.535573450
+0100
@@ -0,0 +1,13 @@
+/* PR rtl-optimization/79909 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mxl-compat" } */
+
+typedef float T __attribute__ ((mode (TD)));
+T b, c, d, e, f, g;
+void bar (T, T, T, T, T, T);
+
+void
+foo (void)
+{
+ bar (e, b, f, c, g, d);
+}
Jakub
