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cmd/compile: instrinsify TrailingZeros{8,32,64} for 386

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This CL add support for instrinsifying the TrialingZeros{8,32,64}
functions for 386 architecture. We need handle the case when the input
is 0, which could lead to undefined output from the BSFL instruction.

Next CL will remove the assembly code in runtime/internal/sys package.

Change-Id: Ic168edf68e81bf69a536102100fdd3f56f0f4a1b
Reviewed-on: https://go-review.googlesource.com/c/go/+/475735
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Wayne Zuo 2023-03-12 15:34:20 +08:00
parent 82bf12902f
commit cedfcba3e8
7 changed files with 77 additions and 3 deletions
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4
test/codegen/mathbits.go
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@ -293,6 +293,7 @@ func RotateLeftVariable32(n uint32, m int) uint32 {
func TrailingZeros(n uint) int {
// amd64/v1,amd64/v2:"BSFQ","MOVL\t\\$64","CMOVQEQ"
// amd64/v3:"TZCNTQ"
// 386:"BSFL"
// arm:"CLZ"
// arm64:"RBIT","CLZ"
// s390x:"FLOGR"
@ -305,6 +306,7 @@ func TrailingZeros(n uint) int {
func TrailingZeros64(n uint64) int {
// amd64/v1,amd64/v2:"BSFQ","MOVL\t\\$64","CMOVQEQ"
// amd64/v3:"TZCNTQ"
// 386:"BSFL"
// arm64:"RBIT","CLZ"
// s390x:"FLOGR"
// ppc64x/power8:"ANDN","POPCNTD"
@ -322,6 +324,7 @@ func TrailingZeros64Subtract(n uint64) int {
func TrailingZeros32(n uint32) int {
// amd64/v1,amd64/v2:"BTSQ\\t\\$32","BSFQ"
// amd64/v3:"TZCNTL"
// 386:"BSFL"
// arm:"CLZ"
// arm64:"RBITW","CLZW"
// s390x:"FLOGR","MOVWZ"
@ -345,6 +348,7 @@ func TrailingZeros16(n uint16) int {
func TrailingZeros8(n uint8) int {
// amd64:"BSFL","BTSL\\t\\$8"
// 386:"BSFL"
// arm:"ORR\t\\$256","CLZ",-"MOVBU\tR"
// arm64:"ORR\t\\$256","RBITW","CLZW",-"MOVBU\tR",-"RBIT\t",-"CLZ\t"
// s390x:"FLOGR","OR\t\\$256"