internal/bytealg: support basic byte operation on loong64

Contributors to the loong64 port are:
  Weining Lu <luweining@loongson.cn>
  Lei Wang <wanglei@loongson.cn>
  Lingqin Gong <gonglingqin@loongson.cn>
  Xiaolin Zhao <zhaoxiaolin@loongson.cn>
  Meidan Li <limeidan@loongson.cn>
  Xiaojuan Zhai <zhaixiaojuan@loongson.cn>
  Qiyuan Pu <puqiyuan@loongson.cn>
  Guoqi Chen <chenguoqi@loongson.cn>

This port has been updated to Go 1.15.6:
  https://github.com/loongson/go

Updates #46229

Change-Id: I4ac6d38dc632abfa0b698325ca0ae349c0d7ecd3
Reviewed-on: https://go-review.googlesource.com/c/go/+/342316
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/internal/bytealg/compare_generic.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !ppc64 && !ppc64le && !mips && !mipsle && !wasm && !mips64 && !mips64le && !riscv64
+//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !loong64 && !ppc64 && !ppc64le && !mips && !mipsle && !wasm && !mips64 && !mips64le && !riscv64
 
 package bytealg
 

src/internal/bytealg/compare_loong64.s

@@ -0,0 +1,86 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+TEXT ·Compare(SB),NOSPLIT,$0-56
+	MOVV	a_base+0(FP), R6
+	MOVV	b_base+24(FP), R7
+	MOVV	a_len+8(FP), R4
+	MOVV	b_len+32(FP), R5
+	MOVV	$ret+48(FP), R13
+	JMP	cmpbody<>(SB)
+
+TEXT runtime·cmpstring(SB),NOSPLIT,$0-40
+	MOVV	a_base+0(FP), R6
+	MOVV	b_base+16(FP), R7
+	MOVV	a_len+8(FP), R4
+	MOVV	b_len+24(FP), R5
+	MOVV	$ret+32(FP), R13
+	JMP	cmpbody<>(SB)
+
+// On entry:
+// R4 length of a
+// R5 length of b
+// R6 points to the start of a
+// R7 points to the start of b
+// R13 points to the return value (-1/0/1)
+TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0
+	BEQ	R6, R7, samebytes // same start of a and b
+
+	SGTU	R4, R5, R9
+	BNE	R0, R9, r2_lt_r1
+	MOVV	R4, R14
+	JMP	entry
+r2_lt_r1:
+	MOVV	R5, R14	// R14 is min(R4, R5)
+entry:
+	ADDV	R6, R14, R12	// R6 start of a, R14 end of a
+	BEQ	R6, R12, samebytes // length is 0
+
+	SRLV	$4, R14		// R14 is number of chunks
+	BEQ	R0, R14, byte_loop
+
+	// make sure both a and b are aligned.
+	OR	R6, R7, R15
+	AND	$7, R15
+	BNE	R0, R15, byte_loop
+
+chunk16_loop:
+	BEQ	R0, R14, byte_loop
+	MOVV	(R6), R8
+	MOVV	(R7), R9
+	BNE	R8, R9, byte_loop
+	MOVV	8(R6), R16
+	MOVV	8(R7), R17
+	ADDV	$16, R6
+	ADDV	$16, R7
+	SUBVU	$1, R14
+	BEQ	R16, R17, chunk16_loop
+	SUBV	$8, R6
+	SUBV	$8, R7
+
+byte_loop:
+	BEQ	R6, R12, samebytes
+	MOVBU	(R6), R8
+	ADDVU	$1, R6
+	MOVBU	(R7), R9
+	ADDVU	$1, R7
+	BEQ	R8, R9, byte_loop
+
+byte_cmp:
+	SGTU	R8, R9, R12 // R12 = 1 if (R8 > R9)
+	BNE	R0, R12, ret
+	MOVV	$-1, R12
+	JMP	ret
+
+samebytes:
+	SGTU	R4, R5, R8
+	SGTU	R5, R4, R9
+	SUBV	R9, R8, R12
+
+ret:
+	MOVV	R12, (R13)
+	RET

src/internal/bytealg/compare_native.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || wasm || mips64 || mips64le || riscv64
+//go:build 386 || amd64 || s390x || arm || arm64 || loong64 || ppc64 || ppc64le || mips || mipsle || wasm || mips64 || mips64le || riscv64
 
 package bytealg
 

src/internal/bytealg/equal_loong64.s

@@ -0,0 +1,52 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+#define	REGCTXT	R29
+
+// memequal(a, b unsafe.Pointer, size uintptr) bool
+TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-25
+	MOVV	a+0(FP), R4
+	MOVV	b+8(FP), R5
+	BEQ	R4, R5, eq
+	MOVV	size+16(FP), R6
+	ADDV	R4, R6, R7
+loop:
+	BNE	R4, R7, test
+	MOVV	$1, R4
+	MOVB	R4, ret+24(FP)
+	RET
+test:
+	MOVBU	(R4), R9
+	ADDV	$1, R4
+	MOVBU	(R5), R10
+	ADDV	$1, R5
+	BEQ	R9, R10, loop
+
+	MOVB	R0, ret+24(FP)
+	RET
+eq:
+	MOVV	$1, R4
+	MOVB	R4, ret+24(FP)
+	RET
+
+// memequal_varlen(a, b unsafe.Pointer) bool
+TEXT runtime·memequal_varlen(SB),NOSPLIT,$40-17
+	MOVV	a+0(FP), R4
+	MOVV	b+8(FP), R5
+	BEQ	R4, R5, eq
+	MOVV	8(REGCTXT), R6    // compiler stores size at offset 8 in the closure
+	MOVV	R4, 8(R3)
+	MOVV	R5, 16(R3)
+	MOVV	R6, 24(R3)
+	JAL	runtime·memequal(SB)
+	MOVBU	32(R3), R4
+	MOVB	R4, ret+16(FP)
+	RET
+eq:
+	MOVV	$1, R4
+	MOVB	R4, ret+16(FP)
+	RET

src/internal/bytealg/indexbyte_generic.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !ppc64 && !ppc64le && !mips && !mipsle && !mips64 && !mips64le && !riscv64 && !wasm
+//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !loong64 && !ppc64 && !ppc64le && !mips && !mipsle && !mips64 && !mips64le && !riscv64 && !wasm
 
 package bytealg
 

src/internal/bytealg/indexbyte_loong64.s

@@ -0,0 +1,52 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+TEXT ·IndexByte(SB),NOSPLIT,$0-40
+	MOVV	b_base+0(FP), R4
+	MOVV	b_len+8(FP), R5
+	MOVBU	c+24(FP), R6	// byte to find
+	MOVV	R4, R7		// store base for later
+	ADDV	R4, R5		// end
+	ADDV	$-1, R4
+
+loop:
+	ADDV	$1, R4
+	BEQ	R4, R5, notfound
+	MOVBU	(R4), R8
+	BNE	R6, R8, loop
+
+	SUBV	R7, R4		// remove base
+	MOVV	R4, ret+32(FP)
+	RET
+
+notfound:
+	MOVV	$-1, R4
+	MOVV	R4, ret+32(FP)
+	RET
+
+TEXT ·IndexByteString(SB),NOSPLIT,$0-32
+	MOVV	s_base+0(FP), R4
+	MOVV	s_len+8(FP), R5
+	MOVBU	c+16(FP), R6	// byte to find
+	MOVV	R4, R7		// store base for later
+	ADDV	R4, R5		// end
+	ADDV	$-1, R4
+
+loop:
+	ADDV	$1, R4
+	BEQ	R4, R5, notfound
+	MOVBU	(R4), R8
+	BNE	R6, R8, loop
+
+	SUBV	R7, R4		// remove base
+	MOVV	R4, ret+24(FP)
+	RET
+
+notfound:
+	MOVV	$-1, R4
+	MOVV	R4, ret+24(FP)
+	RET

src/internal/bytealg/indexbyte_native.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || mips64 || mips64le || riscv64 || wasm
+//go:build 386 || amd64 || s390x || arm || arm64 || loong64 || ppc64 || ppc64le || mips || mipsle || mips64 || mips64le || riscv64 || wasm
 
 package bytealg