runtime: use kernel-supplied cas on linux/arm
Using the kernel-supplied compare-and-swap code
on linux/arm means that runtime doesn't have to care
whether this is GOARM=5 or GOARM=6 anymore.
Fixes #1494.
R=r, r2
CC=golang-dev
https://golang.org/cl/4245043
diff --git a/src/pkg/runtime/Makefile b/src/pkg/runtime/Makefile
index 185397f..e4cc081 100644
--- a/src/pkg/runtime/Makefile
+++ b/src/pkg/runtime/Makefile
@@ -40,11 +40,8 @@
vlop.$O\
vlrt.$O\
-GOARM?=6
-
# arm-specific object files
OFILES_arm=\
- cas$(GOARM).$O\
memset.$O\
softfloat.$O\
vlop.$O\
diff --git a/src/pkg/runtime/arm/asm.s b/src/pkg/runtime/arm/asm.s
index 93c4d4c..f9fe7e6 100644
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/arm/asm.s
@@ -274,3 +274,34 @@
TEXT runtime·runcgocallback(SB),7,$0
MOVW $0, R0
MOVW (R0), R1
+
+// bool armcas(int32 *val, int32 old, int32 new)
+// Atomically:
+// if(*val == old){
+// *val = new;
+// return 1;
+// }else
+// return 0;
+//
+// To implement runtime·cas in ../$GOOS/arm/sys.s
+// using the native instructions, use:
+//
+// TEXT runtime·cas(SB),7,$0
+// B runtime·armcas(SB)
+//
+TEXT runtime·armcas(SB),7,$0
+ MOVW valptr+0(FP), R1
+ MOVW old+4(FP), R2
+ MOVW new+8(FP), R3
+casl:
+ LDREX (R1), R0
+ CMP R0, R2
+ BNE casfail
+ STREX R3, (R1), R0
+ CMP $0, R0
+ BNE casl
+ MOVW $1, R0
+ RET
+casfail:
+ MOVW $0, R0
+ RET
diff --git a/src/pkg/runtime/arm/cas5.s b/src/pkg/runtime/arm/cas5.s
deleted file mode 100644
index d46cdf9..0000000
--- a/src/pkg/runtime/arm/cas5.s
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2009 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 "arm/asm.h"
-
-// This version works on pre v6 architectures
-
-// bool cas(int32 *val, int32 old, int32 new)
-// Atomically:
-// if(*val == old){
-// *val = new;
-// return 1;
-// }else
-// return 0;
-
-TEXT runtime·cas(SB),7,$0
- MOVW 0(FP), R0 // *val
- MOVW 4(FP), R1 // old
- MOVW 8(FP), R2 // new
- MOVW $1, R3
- MOVW $runtime·cas_mutex(SB), R4
- SWPW (R4), R3 // acquire mutex
- CMP $0, R3
- BNE fail0
-
- MOVW (R0), R5
- CMP R1, R5
- BNE fail1
-
- MOVW R2, (R0)
- MOVW R3, (R4) // release mutex
- MOVW $1, R0
- RET
-fail1:
- MOVW R3, (R4) // release mutex
-fail0:
- MOVW $0, R0
- RET
-
-// bool casp(void **p, void *old, void *new)
-// Atomically:
-// if(*p == old){
-// *p = new;
-// return 1;
-// }else
-// return 0;
-
-TEXT runtime·casp(SB),7,$0
- MOVW 0(FP), R0 // *p
- MOVW 4(FP), R1 // old
- MOVW 8(FP), R2 // new
- MOVW $1, R3
- MOVW $runtime·cas_mutex(SB), R4
- SWPW (R4), R3 // acquire mutex
- CMP $0, R3
- BNE failp0
-
- MOVW (R0), R5
- CMP R1, R5
- BNE failp1
-
- MOVW R2, (R0)
- MOVW R3, (R4) // release mutex
- MOVW $1, R0
- RET
-failp1:
- MOVW R3, (R4) // release mutex
-failp0:
- MOVW $0, R0
- RET
-
-DATA runtime·cas_mutex(SB)/4, $0
-GLOBL runtime·cas_mutex(SB), $4
diff --git a/src/pkg/runtime/arm/cas6.s b/src/pkg/runtime/arm/cas6.s
deleted file mode 100644
index ba97771..0000000
--- a/src/pkg/runtime/arm/cas6.s
+++ /dev/null
@@ -1,52 +0,0 @@
-// Copyright 2009 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.
-
-// bool cas(int32 *val, int32 old, int32 new)
-// Atomically:
-// if(*val == old){
-// *val = new;
-// return 1;
-// }else
-// return 0;
-
-TEXT runtime·cas(SB),7,$0
- MOVW 0(FP), R1 // *val
- MOVW 4(FP), R2 // old
- MOVW 8(FP), R3 // new
-l:
- LDREX (R1), R0
- CMP R0, R2
- BNE fail
- STREX R3, (R1), R0
- CMP $0, R0
- BNE l
- MOVW $1, R0
- RET
-fail:
- MOVW $0, R0
- RET
-
-// bool casp(void **p, void *old, void *new)
-// Atomically:
-// if(*p == old){
-// *p = new;
-// return 1;
-// }else
-// return 0;
-TEXT runtime·casp(SB), 7, $0
- MOVW 0(FP), R1 // *p
- MOVW 4(FP), R2 // old
- MOVW 8(FP), R3 // new
-lp:
- LDREX (R1), R0
- CMP R0, R2
- BNE failp
- STREX R3, (R1), R0
- CMP $0, R0
- BNE lp
- MOVW $1, R0
- RET
-failp:
- MOVW $0, R0
- RET
diff --git a/src/pkg/runtime/linux/arm/sys.s b/src/pkg/runtime/linux/arm/sys.s
index 6c222fc..9daf9c2 100644
--- a/src/pkg/runtime/linux/arm/sys.s
+++ b/src/pkg/runtime/linux/arm/sys.s
@@ -230,3 +230,21 @@
MOVW $SYS_rt_sigreturn, R7
SWI $0
RET
+
+// Use kernel version instead of native armcas in ../../arm.s.
+// See ../../../sync/atomic/asm_linux_arm.s for details.
+TEXT cas<>(SB),7,$0
+ MOVW $0xffff0fc0, PC
+
+TEXT runtime·cas(SB),7,$0
+ MOVW valptr+0(FP), R2
+ MOVW old+4(FP), R0
+ MOVW new+8(FP), R1
+ BL cas<>(SB)
+ MOVW $0, R0
+ MOVW.CS $1, R0
+ RET
+
+TEXT runtime·casp(SB),7,$0
+ B runtime·cas(SB)
+
