https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112891
Hongtao Liu <liuhongt at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |x86_64-*-* i?86-*-*
--- Comment #1 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
Aaused by r10-3477-g2a2e3a0dfcbe08, Can be fixed by revert the patch.
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -15032,14 +15032,7 @@ ix86_avx_u128_mode_needed (rtx_insn *insn)
if (avx_upper_reg_found)
return AVX_U128_DIRTY;
- /* If the function is known to preserve some SSE registers,
- RA and previous passes can legitimately rely on that for
- modes wider than 256 bits. It's only safe to issue a
- vzeroupper if all SSE registers are clobbered. */
- const function_abi &abi = insn_callee_abi (insn);
- if (vzeroupper_pattern (PATTERN (insn), VOIDmode)
- || !hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
- abi.mode_clobbers (V4DImode)))
+ if (vzeroupper_pattern (PATTERN (insn), VOIDmode))
return AVX_U128_ANY;
return AVX_U128_CLEAN;
It looks like abi.mode_clobbers is not equal to there's ymm/zmm live through
the callee, it just means callee doens't need to clobber those registers
according to RA. So when there's no 256/512-bit registers live through the
callee there're would be some mistake for the mode. since
ix86_avx_u128_mode_after will return AVX_U128_CLEAN is there's no 256/512-bit
registers are returned, but actaully it 's still dirty for upper bits since
there's no vzeroupper inserted.
