Hi!
The PR109086 r13-6690 inline_string_cmp change to
if (diff != result)
emit_move_insn (result, diff);
regressed
FAIL: go.test/test/fixedbugs/bug207.go, -O2 -g (internal compiler error: in
emit_move_insn, at expr.cc:4224)
The problem is the Go FE doesn't mark __builtin_memcmp as pure (I'll also
send patch for that) and so result is const0_rtx when the call lost its lhs
and the above move ICEs because moving something into const0_rtx is obviously
invalid.
I think it is better not to rely on all FEs having these *cmp functions
pure anD DCE being performed. The following patch just punts from the
inline expansion in that case, so we just emit normal library call.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2023-03-24 Jakub Jelinek <ja...@redhat.com>
PR middle-end/109258
* builtins.cc (inline_expand_builtin_bytecmp): Return NULL_RTX early
if target == const0_rtx.
--- gcc/builtins.cc.jj 2023-03-23 10:00:58.308100548 +0100
+++ gcc/builtins.cc 2023-03-23 11:05:38.308135309 +0100
@@ -7178,8 +7178,8 @@ inline_expand_builtin_bytecmp (tree exp,
bool is_ncmp = (fcode == BUILT_IN_STRNCMP || fcode == BUILT_IN_MEMCMP);
/* Do NOT apply this inlining expansion when optimizing for size or
- optimization level below 2. */
- if (optimize < 2 || optimize_insn_for_size_p ())
+ optimization level below 2 or if unused *cmp hasn't been DCEd. */
+ if (optimize < 2 || optimize_insn_for_size_p () || target == const0_rtx)
return NULL_RTX;
gcc_checking_assert (fcode == BUILT_IN_STRCMP
Jakub
