From 0602e2cdbc4b42e90c453e6ae365ad5f13f61c92 Mon Sep 17 00:00:00 2001
From: Wayne Zuo <wdvxdr@golangcn.org>
Date: Mon, 6 Feb 2023 21:27:37 +0800
Subject: [PATCH] runtime/internal/sys: remove Bswap{32|64} assembly for 386

CL 465515 instrinsify these functions, so that we can remove them.

Change-Id: I81c9eb62ecf56d5a292dc5aced542b36b53847dc
Reviewed-on: https://go-review.googlesource.com/c/go/+/465516
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---
 src/runtime/internal/sys/intrinsics.go        | 32 -------------------
 src/runtime/internal/sys/intrinsics_386.s     | 15 ---------
 src/runtime/internal/sys/intrinsics_common.go | 32 +++++++++++++++++++
 src/runtime/internal/sys/intrinsics_stubs.go  |  2 --
 4 files changed, 32 insertions(+), 49 deletions(-)

diff --git a/src/runtime/internal/sys/intrinsics.go b/src/runtime/internal/sys/intrinsics.go
index 902d893178..b68b3cd93d 100644
--- a/src/runtime/internal/sys/intrinsics.go
+++ b/src/runtime/internal/sys/intrinsics.go
@@ -76,35 +76,3 @@ func TrailingZeros64(x uint64) int {
 func TrailingZeros8(x uint8) int {
 	return int(ntz8tab[x])
 }
-
-// Bswap64 returns its input with byte order reversed
-// 0x0102030405060708 -> 0x0807060504030201
-func Bswap64(x uint64) uint64 {
-	c8 := uint64(0x00ff00ff00ff00ff)
-	a := x >> 8 & c8
-	b := (x & c8) << 8
-	x = a | b
-	c16 := uint64(0x0000ffff0000ffff)
-	a = x >> 16 & c16
-	b = (x & c16) << 16
-	x = a | b
-	c32 := uint64(0x00000000ffffffff)
-	a = x >> 32 & c32
-	b = (x & c32) << 32
-	x = a | b
-	return x
-}
-
-// Bswap32 returns its input with byte order reversed
-// 0x01020304 -> 0x04030201
-func Bswap32(x uint32) uint32 {
-	c8 := uint32(0x00ff00ff)
-	a := x >> 8 & c8
-	b := (x & c8) << 8
-	x = a | b
-	c16 := uint32(0x0000ffff)
-	a = x >> 16 & c16
-	b = (x & c16) << 16
-	x = a | b
-	return x
-}
diff --git a/src/runtime/internal/sys/intrinsics_386.s b/src/runtime/internal/sys/intrinsics_386.s
index f33ade0a3a..fe4c561b99 100644
--- a/src/runtime/internal/sys/intrinsics_386.s
+++ b/src/runtime/internal/sys/intrinsics_386.s
@@ -41,18 +41,3 @@ TEXT runtime∕internal∕sys·TrailingZeros8(SB), NOSPLIT, $0-8
 	MOVL	$8, AX
 	MOVL	AX, ret+4(FP)
 	RET
-
-TEXT runtime∕internal∕sys·Bswap64(SB), NOSPLIT, $0-16
-	MOVL	x_lo+0(FP), AX
-	MOVL	x_hi+4(FP), BX
-	BSWAPL	AX
-	BSWAPL	BX
-	MOVL	BX, ret_lo+8(FP)
-	MOVL	AX, ret_hi+12(FP)
-	RET
-
-TEXT runtime∕internal∕sys·Bswap32(SB), NOSPLIT, $0-8
-	MOVL	x+0(FP), AX
-	BSWAPL	AX
-	MOVL	AX, ret+4(FP)
-	RET
diff --git a/src/runtime/internal/sys/intrinsics_common.go b/src/runtime/internal/sys/intrinsics_common.go
index 1461551dda..78ba44485b 100644
--- a/src/runtime/internal/sys/intrinsics_common.go
+++ b/src/runtime/internal/sys/intrinsics_common.go
@@ -93,6 +93,38 @@ func Len8(x uint8) int {
 	return int(len8tab[x])
 }
 
+// Bswap64 returns its input with byte order reversed
+// 0x0102030405060708 -> 0x0807060504030201
+func Bswap64(x uint64) uint64 {
+	c8 := uint64(0x00ff00ff00ff00ff)
+	a := x >> 8 & c8
+	b := (x & c8) << 8
+	x = a | b
+	c16 := uint64(0x0000ffff0000ffff)
+	a = x >> 16 & c16
+	b = (x & c16) << 16
+	x = a | b
+	c32 := uint64(0x00000000ffffffff)
+	a = x >> 32 & c32
+	b = (x & c32) << 32
+	x = a | b
+	return x
+}
+
+// Bswap32 returns its input with byte order reversed
+// 0x01020304 -> 0x04030201
+func Bswap32(x uint32) uint32 {
+	c8 := uint32(0x00ff00ff)
+	a := x >> 8 & c8
+	b := (x & c8) << 8
+	x = a | b
+	c16 := uint32(0x0000ffff)
+	a = x >> 16 & c16
+	b = (x & c16) << 16
+	x = a | b
+	return x
+}
+
 // Prefetch prefetches data from memory addr to cache
 //
 // AMD64: Produce PREFETCHT0 instruction
diff --git a/src/runtime/internal/sys/intrinsics_stubs.go b/src/runtime/internal/sys/intrinsics_stubs.go
index 66cfcded40..375aac190a 100644
--- a/src/runtime/internal/sys/intrinsics_stubs.go
+++ b/src/runtime/internal/sys/intrinsics_stubs.go
@@ -9,5 +9,3 @@ package sys
 func TrailingZeros64(x uint64) int
 func TrailingZeros32(x uint32) int
 func TrailingZeros8(x uint8) int
-func Bswap64(x uint64) uint64
-func Bswap32(x uint32) uint32
-- 
2.50.0