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cpu: fix AVX512 support detection on Darwin

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Summary: On darwin/amd64, it is not adequate to use OSXSAVE
bits to determine AVX512 availabilty. The reason is involved.
See github issue for details.

The fix consists of implementing Apple's recommended approach
using the process commpage cpu_capabilities bits to determine
availability of AVX512.

Fixes golang/go#43089

Change-Id: I1ba89965498863d268fbf2e427dbfd6429c7409f
Reviewed-on: https://go-review.googlesource.com/c/sys/+/285572
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
This commit is contained in:
Vaughn Iverson
2021-05-03 07:37:44 +00:00
committed by Martin Möhrmann
parent 71e4cd670f
commit b677753862
4 changed files with 42 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
cpu/cpu_x86.go
+8 -2
View File
@@ -87,8 +87,14 @@ func archInit() {
// Check if XMM and YMM registers have OS support.
osSupportsAVX = isSet(1, eax) && isSet(2, eax)
// Check if OPMASK and ZMM registers have OS support.
osSupportsAVX512 = osSupportsAVX && isSet(5, eax) && isSet(6, eax) && isSet(7, eax)
if runtime.GOOS == "darwin" {
// Check darwin commpage for AVX512 support. Necessary because:
// https://github.com/apple/darwin-xnu/blob/0a798f6738bc1db01281fc08ae024145e84df927/osfmk/i386/fpu.c#L175-L201
osSupportsAVX512 = osSupportsAVX && darwinSupportsAVX512()
} else {
// Check if OPMASK and ZMM registers have OS support.
osSupportsAVX512 = osSupportsAVX && isSet(5, eax) && isSet(6, eax) && isSet(7, eax)
}
}
X86.HasAVX = isSet(28, ecx1) && osSupportsAVX