error: ‘asm’ operand has impossible constraints

[chengguosun]

hi,
i compiled the latest blis with gcc7.2, but there was an error as shown below:

kernels/haswell/3/bli_gemm_haswell_asm_d6x8.c: In function ‘bli_sgemm_haswell_asm_6x16’:
./frame/include/bli_x86_asm_macros.h:102:21: error: ‘asm’ operand has impossible
#define BEGIN_ASM() asm volatile (

i found this error caused by "attribute((aligned(BLIS_STACK_BUF_ALIGN_SIZE)))" in bli_edge_case_macro_defs.h, if i delete this line, compilation passed.

if i compile blis with gcc8.5, it passes with no errors. so, I think this may be related to compiler optimization.

[chengguosun]

another problem:
there is "GEMM_UKR_SETUP_CT( s, 16, 6, true );" in bli_gemm_haswell_asm_d8x6.c, Shouldn't it be "GEMM_UKR_SETUP_CT( s, 16, 6, false );"?

[devinamatthews]

another problem:
there is "GEMM_UKR_SETUP_CT( s, 16, 6, true );" in bli_gemm_haswell_asm_d8x6.c, Shouldn't it be "GEMM_UKR_SETUP_CT( s, 16, 6, false );"?

Yes, good catch. This kernel isn't actually used ATM so that slipped through.

[devinamatthews]

Hmmm... the alignment restriction isn't technically necessary for Haswell. I could add another macro for an unaligned buffer although it's a bit hackish.

[devinamatthews]

@chengguosun please test if the linked PR fixes the problem.

[chengguosun]

@devinamatthews yes, the test passed without any problems, thanks.

[ivan23kor]

@devinamatthews this issue still exists on some skx CPUs.

Unfortunately, I could not reproduce the issue on my skx machine and all I have is this log.

Looks like the macros are using alignment for *gemm edge cases in the BLIS version I am using.

Any idea what is wrong?

[devinamatthews]

Does that fork incorporate 7a8e580? If not then you could try just editing GEMM_UKR_SETUP_CT_PRE to remove the alignment attribute.

[ivan23kor]

Yes, the fork incorporates 7a8e580