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cmd/internal/obj/arm64: the encoding of VMOVQ instruction is wrong #50528

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erifan opened this issue Jan 10, 2022 · 1 comment · Fixed by ferrmin/go#267
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cmd/internal/obj/arm64: the encoding of VMOVQ instruction is wrong #50528

erifan opened this issue Jan 10, 2022 · 1 comment · Fixed by ferrmin/go#267
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arch-arm64 FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.

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@erifan
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erifan commented Jan 10, 2022

What version of Go are you using (go version)?

$ go version
tip

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
Linux arm64

What did you do?

VMOVQ $0x1122334455667788, $8877665544332211, V2

What did you expect to see?

As https://pkg.go.dev/cmd/internal/obj/arm64 descripted, the value of V2 should be 0x11223344556677888877665544332211.

What did you see instead?

The value of V2 is 0x88776655443322111122334455667788.

I'm working on a fix.
@erifan erifan self-assigned this Jan 10, 2022
@gopherbot
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Change https://golang.org/cl/377055 mentions this issue: cmd/internal/obj/arm64: fix VMOVQ instruction encoding error

@seankhliao seankhliao added arch-arm64 NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Jan 16, 2022
@ferrmin ferrmin mentioned this issue Jan 18, 2022
Merged
jproberts pushed a commit to jproberts/go that referenced this issue Jun 21, 2022
@jproberts
cmd/internal/obj/arm64: adjust rule for VMOVQ instruction
86eb0c4 
The VMOVQ instruction stores a 128-bit number into a V register, for
example:
    VMOVQ $0x1122334455667788, $0x99aabbccddeeff00, V2
From a documentation (https://pkg.go.dev/cmd/internal/obj/arm64) point
of view, the value in V2 should be 0x112233445566778899aabbccddeeff00,
however the value is actually 0x99aabbccddeeff001122334455667788. The
reason is that we misplaced the high 64-bit and the low 64-bit in the
literal pool. To maintain backward compatibility, this CL adjusts the
rule of VMOVQ instruction to make the documentation consistent with the
code.

Fixes golang#50528

Change-Id: Ib51f59e97c55252ab2a50bbc6ba4d430732a7a04
Reviewed-on: https://go-review.googlesource.com/c/go/+/377055
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Eric Fang <eric.fang@arm.com>
Run-TryBot: Eric Fang <eric.fang@arm.com>
Trust: Eric Fang <eric.fang@arm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
@rsc rsc unassigned erifan Jun 22, 2022
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cmd/internal/obj/arm64: adjust rule for VMOVQ instruction golang/go
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@gopherbot @seankhliao @erifan