cmd/asm: "invalid instruction" error for VPERMQ. #24378
Description
What version of Go are you using (go version)?
go version go1.10 linux/amd64
Does this issue reproduce with the latest release?
Yes
What did you do?
Ported assembly from an existing project (gas) to Go's dialect, which uses VPERMQ.
VPERMQ $0xd8,Y4,Y4
VPERMQ $0xd8,Y5,Y5
VPERMQ $0xd8,Y6,Y6
VPERMQ $0xd8,Y7,Y7
What did you expect to see?
Working output.
What did you see instead?
asm: invalid instruction: 00152 (/home/yawning/Documents/Development/go-workspace/src/git.schwanenlied.me/yawning/kyber.git/hwaccel_amd64.s:1183) VPERMQ$216, Y4, Y4
asm: invalid instruction: 00152 (/home/yawning/Documents/Development/go-workspace/src/git.schwanenlied.me/yawning/kyber.git/hwaccel_amd64.s:1184) VPERMQ$216, Y5, Y5
asm: invalid instruction: 00152 (/home/yawning/Documents/Development/go-workspace/src/git.schwanenlied.me/yawning/kyber.git/hwaccel_amd64.s:1185) VPERMQ$216, Y6, Y6
asm: invalid instruction: 00152 (/home/yawning/Documents/Development/go-workspace/src/git.schwanenlied.me/yawning/kyber.git/hwaccel_amd64.s:1186) VPERMQ$216, Y7, Y7
@mvdan tells me that the assembler is choking on the imm8 because it is > 127 due to the use of a int8 internally in the assembler, which is incorrect as the argument is 4 2-bit indices.