diff options
Diffstat (limited to 'src/runtime/asm_amd64.s')
| -rw-r--r-- | src/runtime/asm_amd64.s | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s index b4df1d80d7..83db4d3e81 100644 --- a/src/runtime/asm_amd64.s +++ b/src/runtime/asm_amd64.s @@ -28,6 +28,7 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0 // find out information about the processor we're on MOVQ $0, AX CPUID + MOVQ AX, SI CMPQ AX, $0 JE nocpuinfo @@ -42,15 +43,25 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0 JNE notintel MOVB $1, runtime·lfenceBeforeRdtsc(SB) notintel: - // Do nothing. + // Load EAX=1 cpuid flags MOVQ $1, AX CPUID MOVL CX, runtime·cpuid_ecx(SB) MOVL DX, runtime·cpuid_edx(SB) + + // Load EAX=7/ECX=0 cpuid flags + CMPQ SI, $7 + JLT no7 + MOVL $7, AX + MOVL $0, CX + CPUID + MOVL BX, runtime·cpuid_ebx7(SB) +no7: // Detect AVX and AVX2 as per 14.7.1 Detection of AVX2 chapter of [1] // [1] 64-ia-32-architectures-software-developer-manual-325462.pdf // http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf + MOVL runtime·cpuid_ecx(SB), CX ANDL $0x18000000, CX // check for OSXSAVE and AVX bits CMPL CX, $0x18000000 JNE noavx @@ -61,12 +72,8 @@ notintel: CMPL AX, $6 // Check for OS support of YMM registers JNE noavx MOVB $1, runtime·support_avx(SB) - MOVL $7, AX - MOVL $0, CX - CPUID - ANDL $0x20, BX // check for AVX2 bit - CMPL BX, $0x20 - JNE noavx2 + TESTL $(1<<5), runtime·cpuid_ebx7(SB) // check for AVX2 bit + JEQ noavx2 MOVB $1, runtime·support_avx2(SB) JMP nocpuinfo noavx: |