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chore: get rid of the golang.org/x/sys/cpu #75

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@rinor rinor commented May 13, 2024

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@rinor rinor marked this pull request as ready for review May 17, 2024 20:46
@@ -0,0 +1,55 @@
/* This file is a copy of https://cs.opensource.google/go/x/sys/+/master:cpu/cpu_x86.s.
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In case their file changes in the future, it might be better to reference a specific version of it

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/* This file is a copy of https://cs.opensource.google/go/x/sys/+/master:cpu/cpu_x86.s.
/* This file is a copy of https://cs.opensource.google/go/x/sys/+/refs/tags/v0.20.0:cpu/cpu_x86.s.

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Is this the required subset of the x/sys/cpu's cpu.X86.HasAVX2 and cpu.X86.HasFMA checks? (Sorry currently don't have much time to confirm myself)

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Ah thanks! Checked it and commented a question below

@philippgille
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Thank you so much for looking into this! 👍

OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "textflag.h"
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@philippgille philippgille May 20, 2024

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Do you know if this could lead to any constraints on users' side? Does it work when using TinyGo as compiler? (Haven't tried with current chromem-go either though)

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@rinor rinor May 21, 2024

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Do you know if this could lead to any constraints on users' side?

not really, as long as we take care of proper build tags, nothing should break or cause additional constraints (we have default fallback)

Does it work when using TinyGo as compiler?

iirc,

  • TinyGo doesn't currently enable support for AVX instructions,
  • TinyGo does not support Go's Assembler, so we should skip building those files

If we want to attempt to build TinyGo "normal" binaries we can manage the builds with the tinygo build tag so building on amd64 with TinyGo will just skip the custom code.
I will take care of that.

However I don't think tinygo works right now (unrelated to the changes being worked on here). Tried quickly to build the minimal example with TinyGo and it panics

checkId: 22 should be 23
panic: bootstrap type wrong id: mapType mapType not <nil>

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It would be // +build !tinygo in both this assembly file and the cpu_amd64.go one, right?

if hasOSXSAVE := isSet(27, ecx1); hasOSXSAVE {
eax, _ := xgetbv() // For XGETBV, OSXSAVE bit is required and sufficient.
_, ebx7, _, _ := cpuid(7, 0)
hasAVX2 = isSet(1, eax) && isSet(2, eax) && isSet(5, ebx7)
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Are only these checks needed? In the reference code it appears to do, for non-Darwin OS: isSet(1, eax) && isSet(2, eax) && isSet(5, eax) && isSet(6, eax) && isSet(7, eax) && isSet(5, ebx7), based on this, this and this.

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Ah thanks! Checked it and commented a question below

OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include "textflag.h"
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It would be // +build !tinygo in both this assembly file and the cpu_amd64.go one, right?

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