runtime: implement cmpstring and bytes.Compare in assembly for ppc64

Change-Id: I15bf55aa5ac3588c05f0a253f583c52bab209892
Reviewed-on: https://go-review.googlesource.com/14041
Reviewed-by: Dave Cheney <dave@cheney.net>

diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s
index 60e6b8c4a4998547c8a57ff872c65d8790b8ba92..6646dd8b9d0a8e97d0cecf8a323720ed196cba0b 100644 (file)
--- a/src/runtime/asm_ppc64x.s
+++ b/src/runtime/asm_ppc64x.s
@@ -1115,6 +1115,65 @@ notfound:
        MOVD    R3, ret+24(FP)
        RET
 
+TEXT runtime·cmpstring(SB),NOSPLIT,$-4-40
+       MOVD    s1_base+0(FP), R5
+       MOVD    s1_len+8(FP), R3
+       MOVD    s2_base+16(FP), R6
+       MOVD    s2_len+24(FP), R4
+       MOVD    $ret+32(FP), R7
+       BR      runtime·cmpbody<>(SB)
+
+TEXT bytes·Compare(SB),NOSPLIT,$-4-56
+       MOVD    s1+0(FP), R5
+       MOVD    s1+8(FP), R3
+       MOVD    s2+24(FP), R6
+       MOVD    s2+32(FP), R4
+       MOVD    $ret+48(FP), R7
+       BR      runtime·cmpbody<>(SB)
+
+// On entry:
+// R3 is the length of s1
+// R4 is the length of s2
+// R5 points to the start of s1
+// R6 points to the start of s2
+// R7 points to return value (-1/0/1 will be written here)
+//
+// On exit:
+// R5, R6, R8, R9 and R10 are clobbered
+TEXT runtime·cmpbody<>(SB),NOSPLIT,$-4-0
+       CMP     R5, R6
+       BEQ     samebytes // same starting pointers; compare lengths
+       SUB     $1, R5
+       SUB     $1, R6
+       MOVD    R4, R8
+       CMP     R3, R4
+       BGE     2(PC)
+       MOVD    R3, R8  // R8 is min(R3, R4)
+       ADD     R5, R8  // R5 is current byte in s1, R8 is last byte in s1 to compare
+loop:
+       CMP     R5, R8
+       BEQ     samebytes // all compared bytes were the same; compare lengths
+       MOVBZU  1(R5), R9
+       MOVBZU  1(R6), R10
+       CMP     R9, R10
+       BEQ     loop
+       // bytes differed
+       MOVD    $1, R4
+       BGT     2(PC)
+       NEG     R4
+       MOVD    R4, (R7)
+       RET
+samebytes:
+       MOVD    $1, R8
+       CMP     R3, R4
+       BNE     3(PC)
+       MOVD    R0, (R7)
+       RET
+       BGT     2(PC)
+       NEG     R8
+       MOVD    R8, (R7)
+       RET
+
 TEXT runtime·fastrand1(SB), NOSPLIT, $0-4
        MOVD    g_m(g), R4
        MOVWZ   m_fastrand(R4), R3

diff --git a/src/runtime/noasm.go b/src/runtime/noasm.go
index 218e121bf7685b45cdc00c730bad6b147cee7c58..30fa31c3abbbde69f8baacb92f38e4a35000b04c 100644 (file)
--- a/src/runtime/noasm.go
+++ b/src/runtime/noasm.go
@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Routines that are implemented in assembly in asm_{amd64,386,arm,arm64}.s
+// Routines that are implemented in assembly in asm_{amd64,386,arm,arm64,ppc64x}.s
 
-// +build ppc64 ppc64le
+// +build ignore
 
 package runtime