https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119617
--- Comment #11 from Haochen Jiang <haochen.jiang at intel dot com> ---
We have two temporary solutions in GCC 14 and GCC 15 since we could not simply
reject -mno-evex512. In GCC 16, since it is deprecated, no more issue for that.
Plan A: Use vmovq to only clear lower 64 bit.
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -5453,7 +5453,7 @@ standard_sse_constant_opcode (rtx_insn *insn, rtx
*operands)
else if (TARGET_EVEX512)
return "vxorps\t%g0, %g0, %g0";
else
- gcc_unreachable ();
+ return "xor\t%%rax, %%rax\n\tvmovq\t{%%rax, %x0|%x0,
%%rax}";
}
else
{
@@ -5462,7 +5462,7 @@ standard_sse_constant_opcode (rtx_insn *insn, rtx
*operands)
else if (TARGET_EVEX512)
return "vpxord\t%g0, %g0, %g0";
else
- gcc_unreachable ();
+ return "xor\t%%rax, %%rax\n\tvmovq\t{%%rax, %x0|%x0,
%%rax}";
}
}
return "vxorps\t%x0, %x0, %x0";
Plan B: Clear the whole zmm even this is under -mno-evex512 since all HW could
run that code.
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 4f8380c4a58..f1e5535bf71 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -5450,19 +5450,15 @@ standard_sse_constant_opcode (rtx_insn *insn, rtx
*operands)
{
if (TARGET_AVX512VL)
return "vxorps\t%x0, %x0, %x0";
- else if (TARGET_EVEX512)
- return "vxorps\t%g0, %g0, %g0";
else
- gcc_unreachable ();
+ return "vxorps\t%g0, %g0, %g0";
}
else
{
if (TARGET_AVX512VL)
return "vpxord\t%x0, %x0, %x0";
- else if (TARGET_EVEX512)
- return "vpxord\t%g0, %g0, %g0";
else
- gcc_unreachable ();
+ return "vpxord\t%g0, %g0, %g0";
}
}
return "vxorps\t%x0, %x0, %x0";
I am ok with both. Which way do you prefer?
