https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103661
--- Comment #4 from Stefan Kneifel <stefan.kneifel at bluewin dot ch> --- Created attachment 51978 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51978&action=edit Testcase Without the proposed patch, it compiles to: -------- 0000000000000000 <has_vbmi>: 0: 50 push %rax 1: e8 00 00 00 00 call 6 <has_vbmi+0x6> 2: R_X86_64_PLT32 __cpu_indicator_init-0x4 6: 31 c0 xor %eax,%eax 8: f6 05 00 00 00 00 04 testb $0x4,0x0(%rip) # f <has_vbmi+0xf> a: R_X86_64_PC32 __cpu_model+0xa f: 5a pop %rdx 10: 0f 95 c0 setne %al 13: c3 ret 0000000000000014 <has_vbmi2>: 14: 50 push %rax 15: e8 00 00 00 00 call 1a <has_vbmi2+0x6> 16: R_X86_64_PLT32 __cpu_indicator_init-0x4 1a: 31 c0 xor %eax,%eax 1c: 5a pop %rdx 1d: c3 ret -------- returning 1 only for avx512vbmi, but not for avx512vbmi2, where it returns always zero regardless whether the machine has it or not. With the proposed patch, it compiles to: -------- 0000000000000000 <has_vbmi>: 0: 50 push %rax 1: e8 00 00 00 00 call 6 <has_vbmi+0x6> 2: R_X86_64_PLT32 __cpu_indicator_init-0x4 6: 8b 05 00 00 00 00 mov 0x0(%rip),%eax # c <has_vbmi+0xc> 8: R_X86_64_PC32 __cpu_model+0x8 c: 5a pop %rdx d: c1 e8 1a shr $0x1a,%eax 10: 83 e0 01 and $0x1,%eax 13: c3 ret 0000000000000014 <has_vbmi2>: 14: 50 push %rax 15: e8 00 00 00 00 call 1a <has_vbmi2+0x6> 16: R_X86_64_PLT32 __cpu_indicator_init-0x4 1a: 8b 05 00 00 00 00 mov 0x0(%rip),%eax # 20 <has_vbmi2+0xc> 1c: R_X86_64_PC32 __cpu_model+0x8 20: 5a pop %rdx 21: c1 e8 1f shr $0x1f,%eax 24: c3 ret -------- returning correctly 1 if the machine has avx512vbmi2.
