strings: use runtime assembly for IndexByte
Fixes #3751
R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/12483043
diff --git a/src/pkg/runtime/asm_386.s b/src/pkg/runtime/asm_386.s
index f6204ac..863bcc3 100644
--- a/src/pkg/runtime/asm_386.s
+++ b/src/pkg/runtime/asm_386.s
@@ -504,7 +504,7 @@
// so actually
// void atomicload64(uint64 *res, uint64 volatile *addr);
TEXT runtime·atomicload64(SB), 7, $0-8
- MOVL 4(SP), BX
+ MOVL 4(SP), BX
MOVL 8(SP), AX
// MOVQ (%EAX), %MM0
BYTE $0x0f; BYTE $0x6f; BYTE $0x00
@@ -1220,6 +1220,20 @@
MOVL DI, ret+16(FP)
RET
+TEXT strings·IndexByte(SB),7,$0
+ MOVL s+0(FP), SI
+ MOVL s_len+4(FP), CX
+ MOVB c+8(FP), AL
+ MOVL SI, DI
+ CLD; REPN; SCASB
+ JZ 3(PC)
+ MOVL $-1, ret+12(FP)
+ RET
+ SUBL SI, DI
+ SUBL $1, DI
+ MOVL DI, ret+12(FP)
+ RET
+
// input:
// SI = a
// DI = b
