Revert "internal/bytealg: add assembly implementation of Compare/CompareString on mips64x"

This reverts CL 196837 (commit 78baea83).

Reason for revert: broke the mips64le build.

Change-Id: I531da60d098cb227659c9977a3d229474325b0a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/197538
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <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.
 
-// +build !386,!amd64,!amd64p32,!s390x,!arm,!arm64,!ppc64,!ppc64le,!mips,!mipsle,!wasm,!mips64,!mips64le
+// +build !386,!amd64,!amd64p32,!s390x,!arm,!arm64,!ppc64,!ppc64le,!mips,!mipsle,!wasm
 
 package bytealg
 

src/internal/bytealg/compare_mips64x.s

-// Copyright 2019 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.
-
-// +build mips64 mips64le
-
-#include "go_asm.h"
-#include "textflag.h"
-
-TEXT ·Compare(SB),NOSPLIT,$0-56
-	MOVV	a_base+0(FP), R3
-	MOVV	b_base+24(FP), R4
-	MOVV	a_len+8(FP), R1
-	MOVV	b_len+32(FP), R2
-	MOVV	$ret+48(FP), R9
-	JMP	cmpbody<>(SB)
-
-TEXT runtime·cmpstring(SB),NOSPLIT,$0-40
-	MOVV	a_base+0(FP), R3
-	MOVV	b_base+16(FP), R4
-	MOVV	a_len+8(FP), R1
-	MOVV	b_len+24(FP), R2
-	MOVV	$ret+32(FP), R9
-	JMP	cmpbody<>(SB)
-
-// On entry:
-// R1 length of a
-// R2 length of b
-// R3 points to the start of a
-// R4 points to the start of b
-// R9 points to the return value (-1/0/1)
-//
-// On exit:
-// R6, R7, R8, R10, R11, R13, R14 clobbered
-TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0
-	BEQ	R3, R4, samebytes // same start of a and b
-
-	SGTU	R1, R2, R7
-	BNE	R0, R7, r2_lt_r1
-	MOVV	R1, R10
-	JMP	entry
-r2_lt_r1:
-	MOVV	R2, R10	// R10 is min(R1, R2)
-entry:
-	ADDV	R3, R10, R8	// R3 start of a, R8 end of a
-	BEQ	R3, R8, samebytes // length is 0
-
-	SRLV	$4, R10		// R10 is number of chunks
-	BEQ	R0, R10, byte_loop
-
-	// make sure both a and b are aligned.
-	OR	R3, R4, R11
-	AND	$7, R11
-	BNE	R0, R11, byte_loop
-
-chunk16_loop:
-	BEQ	R0, R10, byte_loop
-	MOVV	(R3), R6
-	MOVV	(R4), R7
-	BNE	R6, R7, byte_cmp
-	MOVV	8(R3), R13
-	MOVV	8(R4), R14
-	ADDV	$16, R3
-	ADDV	$16, R4
-	SUBVU	$1, R10
-	BEQ	R13, R14, chunk16_loop
-	MOVV	R13, R6
-	MOVV	R14, R7
-	JMP	byte_cmp
-
-byte_loop:
-	BEQ	R3, R8, samebytes
-	MOVBU	(R3), R6
-	ADDVU	$1, R3
-	MOVBU	(R4), R7
-	ADDVU	$1, R4
-	BEQ	R6, R7, byte_loop
-
-byte_cmp:
-	SGTU	R6, R7, R8 // R8 = 1 if (R6 > R7)
-	BNE	R0, R8, ret
-	MOVV	$-1, R8
-	JMP	ret
-
-samebytes:
-	SGTU	R1, R2, R6
-	SGTU	R2, R1, R7
-	SUBV	R7, R6, R8
-
-ret:
-	MOVV	R8, (R9)
-	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.
 
-// +build 386 amd64 amd64p32 s390x arm arm64 ppc64 ppc64le mips mipsle mips64 mips64le wasm
+// +build 386 amd64 amd64p32 s390x arm arm64 ppc64 ppc64le mips mipsle wasm
 
 package bytealg