https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126933
Bug ID: 126933
Summary: FAIL: gcc.target/i386/truncsfbf-2.c execution test
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
Blocks: 126927
Target Milestone: ---
Target: x86
On x86-64, when AVX512BF16 is enabled by default, I got
FAIL: gcc.target/i386/truncsfbf-2.c execution test
The codegen differences for
__bf16
foo (float a)
{
return a;
}
are
Dump of assembler code for function foo:
0x0000000000401166 <+0>: push %rbp
0x0000000000401167 <+1>: mov %rsp,%rbp
0x000000000040116a <+4>: movss %xmm0,-0x4(%rbp)
0x000000000040116f <+9>: movss -0x4(%rbp),%xmm0
0x0000000000401174 <+14>: psrld $0x10,%xmm0
0x0000000000401179 <+19>: movd %xmm0,%eax
0x000000000040117d <+23>: movd %eax,%xmm0
0x0000000000401181 <+27>: pop %rbp
0x0000000000401182 <+28>: ret
End of assembler dump.
vs
Dump of assembler code for function foo:
0x0000000000401166 <+0>: push %rbp
0x0000000000401167 <+1>: mov %rsp,%rbp
0x000000000040116a <+4>: vmovss %xmm0,-0x4(%rbp)
0x000000000040116f <+9>: vmovss -0x4(%rbp),%xmm0
0x0000000000401174 <+14>: vcvtneps2bf16 %xmm0,%xmm0
0x000000000040117a <+20>: vmovd %xmm0,%eax
0x000000000040117e <+24>: vmovd %eax,%xmm0
0x0000000000401182 <+28>: pop %rbp
0x0000000000401183 <+29>: ret
End of assembler dump.
For the float value of 1e-8f, vcvtneps2bf16 generates 1.001e-08 while
GCC emulation generates 9.954e-09. Should GCC emulation generate
1.001e-08?
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126927
[Bug 126927] FAIL: gcc.target/x86_64/abi/ms-sysv/ms-sysv.c
