runtime, syscall: use FP instead of SP for parameters

Consistently access function parameters using the FP pseudo-register
instead of SP (e.g., x+0(FP) instead of x+4(SP) or x+8(SP), depending
on register size). Two reasons: 1) doc/asm says the SP pseudo-register
should use negative offsets in the range [-framesize, 0), and 2)
cmd/vet only validates parameter offsets when indexed from the FP
pseudo-register.

No binary changes to the compiled object files for any of the affected
package/OS/arch combinations.

Change-Id: I0efc6079bc7519fcea588c114ec6a39b245d68b0
Reviewed-on: https://go-review.googlesource.com/30085Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/sys_dragonfly_amd64.s

@@ -237,8 +237,8 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
 	RET
 	
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
-	MOVQ	new+8(SP), DI
-	MOVQ	old+16(SP), SI
+	MOVQ	new+0(FP), DI
+	MOVQ	old+8(FP), SI
 	MOVQ	$53, AX
 	SYSCALL
 	JCC	2(PC)

src/runtime/sys_freebsd_amd64.s

@@ -229,8 +229,8 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
 	RET
 	
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
-	MOVQ	new+8(SP), DI
-	MOVQ	old+16(SP), SI
+	MOVQ	new+0(FP), DI
+	MOVQ	old+8(FP), SI
 	MOVQ	$53, AX
 	SYSCALL
 	JCC	2(PC)

src/runtime/sys_linux_386.s

@@ -379,8 +379,8 @@ nog:
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
 	MOVL	$186, AX	// sigaltstack
-	MOVL	new+4(SP), BX
-	MOVL	old+8(SP), CX
+	MOVL	new+0(FP), BX
+	MOVL	old+4(FP), CX
 	INVOKE_SYSCALL
 	CMPL	AX, $0xfffff001
 	JLS	2(PC)

src/runtime/sys_linux_amd64.s

@@ -445,8 +445,8 @@ nog:
 	JMP	-3(PC)	// keep exiting
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
-	MOVQ	new+8(SP), DI
-	MOVQ	old+16(SP), SI
+	MOVQ	new+0(FP), DI
+	MOVQ	old+8(FP), SI
 	MOVQ	$131, AX
 	SYSCALL
 	CMPQ	AX, $0xfffffffffffff001

src/runtime/sys_netbsd_386.s

@@ -285,8 +285,8 @@ TEXT runtime·lwp_tramp(SB),NOSPLIT,$0
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
 	MOVL	$281, AX		// sys___sigaltstack14
-	MOVL	new+4(SP), BX
-	MOVL	old+8(SP), CX
+	MOVL	new+0(FP), BX
+	MOVL	old+4(FP), CX
 	INT	$0x80
 	CMPL	AX, $0xfffff001
 	JLS	2(PC)

src/runtime/sys_netbsd_amd64.s

@@ -290,8 +290,8 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
 	RET
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
-	MOVQ	new+8(SP), DI		// arg 1 - nss
-	MOVQ	old+16(SP), SI		// arg 2 - oss
+	MOVQ	new+0(FP), DI		// arg 1 - nss
+	MOVQ	old+8(FP), SI		// arg 2 - oss
 	MOVQ	$281, AX		// sys___sigaltstack14
 	SYSCALL
 	JCC	2(PC)

src/runtime/sys_openbsd_386.s

@@ -294,8 +294,8 @@ TEXT runtime·tfork(SB),NOSPLIT,$12
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
 	MOVL	$288, AX		// sys_sigaltstack
-	MOVL	new+4(SP), BX
-	MOVL	old+8(SP), CX
+	MOVL	new+0(FP), BX
+	MOVL	old+4(FP), CX
 	INT	$0x80
 	CMPL	AX, $0xfffff001
 	JLS	2(PC)

src/runtime/sys_openbsd_amd64.s

@@ -278,8 +278,8 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
 	RET
 
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
-	MOVQ	new+8(SP), DI		// arg 1 - nss
-	MOVQ	old+16(SP), SI		// arg 2 - oss
+	MOVQ	new+0(FP), DI		// arg 1 - nss
+	MOVQ	old+8(FP), SI		// arg 2 - oss
 	MOVQ	$288, AX		// sys_sigaltstack
 	SYSCALL
 	JCC	2(PC)

src/runtime/sys_plan9_386.s

@@ -178,8 +178,8 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	RET
 
 	// save args
-	MOVL	ureg+4(SP), CX
-	MOVL	note+8(SP), DX
+	MOVL	ureg+0(FP), CX
+	MOVL	note+4(FP), DX
 
 	// change stack
 	MOVL	g_m(BX), BX

src/runtime/sys_plan9_amd64.s

@@ -179,8 +179,8 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$0
 	RET
 
 	// save args
-	MOVQ	ureg+8(SP), CX
-	MOVQ	note+16(SP), DX
+	MOVQ	ureg+0(FP), CX
+	MOVQ	note+8(FP), DX
 
 	// change stack
 	MOVQ	g_m(BX), BX

src/runtime/sys_windows_386.s

@@ -309,7 +309,7 @@ TEXT runtime·callbackasm1+0(SB),NOSPLIT,$0
 
 // void tstart(M *newm);
 TEXT runtime·tstart(SB),NOSPLIT,$0
-	MOVL	newm+4(SP), CX		// m
+	MOVL	newm+0(FP), CX		// m
 	MOVL	m_g0(CX), DX		// g
 
 	// Layout new m scheduler stack on os stack.
@@ -337,7 +337,7 @@ TEXT runtime·tstart(SB),NOSPLIT,$0
 
 // uint32 tstart_stdcall(M *newm);
 TEXT runtime·tstart_stdcall(SB),NOSPLIT,$0
-	MOVL	newm+4(SP), BX
+	MOVL	newm+0(FP), BX
 
 	PUSHL	BX
 	CALL	runtime·tstart(SB)

src/syscall/asm_darwin_arm.s

@@ -11,124 +11,123 @@
 // func Syscall(syscall uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr)
 TEXT	·Syscall(SB),NOSPLIT,$0-28
 	BL		runtime·entersyscall(SB)
-	MOVW	syscall+4(SP), R12
-	MOVW	a1+8(SP), R0
-	MOVW	a2+12(SP), R1
-	MOVW	a3+16(SP), R2
+	MOVW	syscall+0(FP), R12
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
 	SWI		$0x80
 	BCC		ok
 	MOVW	$-1, R1
-	MOVW	R1, r1+20(SP)	// r1
+	MOVW	R1, r1+16(FP)	// r1
 	MOVW	$0, R2
-	MOVW	R2, r2+24(SP)	// r2
-	MOVW	R0, errno+28(SP)	// errno
+	MOVW	R2, r2+20(FP)	// r2
+	MOVW	R0, errno+24(FP)	// errno
 	BL		runtime·exitsyscall(SB)
 	RET
 ok:
-	MOVW	R0, r1+20(SP) // r1
-	MOVW	R1, r2+24(SP)	// r2
+	MOVW	R0, r1+16(FP) // r1
+	MOVW	R1, r2+20(FP)	// r2
 	MOVW	$0, R0
-	MOVW	R0, errno+28(SP)	// errno
+	MOVW	R0, errno+24(FP)	// errno
 	BL		runtime·exitsyscall(SB)
 	RET
 
 // func RawSyscall(trap uintptr, a1, a2, a3 uintptr) (r1, r2, err uintptr)
 TEXT ·RawSyscall(SB),NOSPLIT,$0-28
-	MOVW	syscall+4(SP), R12	// syscall entry
-	MOVW	a1+8(SP), R0
-	MOVW	a2+12(SP), R1
-	MOVW	a3+16(SP), R2
+	MOVW	syscall+0(FP), R12	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
 	SWI		$0x80
 	BCC		ok1
 	MOVW	$-1, R1
-	MOVW	R1, r1+20(SP)	// r1
+	MOVW	R1, r1+16(FP)	// r1
 	MOVW	$0, R2
-	MOVW	R2, r2+24(SP)	// r2
-	MOVW	R0, errno+28(SP)	// errno
+	MOVW	R2, r2+20(FP)	// r2
+	MOVW	R0, errno+24(FP)	// errno
 	RET
 ok1:
-	MOVW	R0, r1+20(SP) // r1
-	MOVW	R1, r2+24(SP)	// r2
+	MOVW	R0, r1+16(FP) // r1
+	MOVW	R1, r2+20(FP)	// r2
 	MOVW	$0, R0
-	MOVW	R0, errno+28(SP)	// errno
+	MOVW	R0, errno+24(FP)	// errno
 	RET
 
 // func Syscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
 TEXT	·Syscall6(SB),NOSPLIT,$0-40
 	BL		runtime·entersyscall(SB)
-	MOVW	syscall+4(SP), R12	// syscall entry
-	MOVW	a1+8(SP), R0
-	MOVW	a2+12(SP), R1
-	MOVW	a3+16(SP), R2
-	MOVW	a4+20(SP), R3
-	MOVW	a5+24(SP), R4
-	MOVW	a6+28(SP), R5
+	MOVW	syscall+0(FP), R12	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	MOVW	a4+16(FP), R3
+	MOVW	a5+20(FP), R4
+	MOVW	a6+24(FP), R5
 	SWI		$0x80
 	BCC		ok6
 	MOVW	$-1, R1
-	MOVW	R1, r1+32(SP)	// r1
+	MOVW	R1, r1+28(FP)	// r1
 	MOVW	$0, R2
-	MOVW	R2, r2+36(SP)	// r2
-	MOVW	R0, errno+40(SP)	// errno
+	MOVW	R2, r2+32(FP)	// r2
+	MOVW	R0, errno+36(FP)	// errno
 	BL		runtime·exitsyscall(SB)
 	RET
 ok6:
-	MOVW	R0, r1+32(SP) // r1
-	MOVW	R1, r2+36(SP)	// r2
+	MOVW	R0, r1+28(FP) // r1
+	MOVW	R1, r2+32(FP)	// r2
 	MOVW	$0, R0
-	MOVW	R0, errno+40(SP)	// errno
+	MOVW	R0, errno+36(FP)	// errno
 	BL		runtime·exitsyscall(SB)
 	RET
 
 // func RawSyscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
 TEXT	·RawSyscall6(SB),NOSPLIT,$0-40
-	MOVW	trap+4(SP), R12	// syscall entry
-	MOVW	a1+8(SP), R0
-	MOVW	a2+12(SP), R1
-	MOVW	a3+16(SP), R2
-	MOVW	a4+20(SP), R3
-	MOVW	a5+24(SP), R4
-	MOVW	a6+28(SP), R5
+	MOVW	trap+0(FP), R12	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	MOVW	a4+16(FP), R3
+	MOVW	a5+20(FP), R4
+	MOVW	a6+24(FP), R5
 	SWI		$0x80
 	BCC		ok2
 	MOVW	$-1, R1
-	MOVW	R1, r1+32(SP)	// r1
+	MOVW	R1, r1+28(FP)	// r1
 	MOVW	$0, R2
-	MOVW	R2, r2+36(SP)	// r2
-	MOVW	R0, errno+40(SP)	// errno
+	MOVW	R2, r2+32(FP)	// r2
+	MOVW	R0, errno+36(FP)	// errno
 	RET
 ok2:
-	MOVW	R0, r1+32(SP) // r1
-	MOVW	R1, r2+36(SP)	// r2
+	MOVW	R0, r1+28(FP) // r1
+	MOVW	R1, r2+32(FP)	// r2
 	MOVW	$0, R0
-	MOVW	R0, errno+40(SP)	// errno
+	MOVW	R0, errno+36(FP)	// errno
 	RET
 
 // Actually Syscall7.
 TEXT	·Syscall9(SB),NOSPLIT,$0-52
 	BL runtime·entersyscall(SB)
-	MOVW	syscall+4(SP), R12	// syscall entry
-	MOVW	a1+8(SP), R0
-	MOVW	a2+12(SP), R1
-	MOVW	a3+16(SP), R2
-	MOVW	a4+20(SP), R3
-	MOVW	a5+24(SP), R4
-	MOVW	a6+28(SP), R5
-	MOVW	a7+32(SP), R6
+	MOVW	syscall+0(FP), R12	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	MOVW	a4+16(FP), R3
+	MOVW	a5+20(FP), R4
+	MOVW	a6+24(FP), R5
+	MOVW	a7+28(FP), R6
 	SWI		$0x80
 	BCC		ok9
 	MOVW	$-1, R1
-	MOVW	R1, r1+44(SP)	// r1
+	MOVW	R1, r1+40(FP)	// r1
 	MOVW	$0, R2
-	MOVW	R2, r2+48(SP)	// r2
-	MOVW	R0, errno+52(SP)	// errno
+	MOVW	R2, r2+44(FP)	// r2
+	MOVW	R0, errno+48(FP)	// errno
 	BL		runtime·exitsyscall(SB)
 	RET
 ok9:
-	MOVW	R0, r1+44(SP) // r1
-	MOVW	R1, r2+48(SP)	// r2
+	MOVW	R0, r1+40(FP) // r1
+	MOVW	R1, r2+44(FP)	// r2
 	MOVW	$0, R0
-	MOVW	R0, errno+52(SP)	// errno
+	MOVW	R0, errno+48(FP)	// errno
 	BL	runtime·exitsyscall(SB)
 	RET
-

src/syscall/asm_plan9_386.s

@@ -29,8 +29,8 @@ TEXT	·Syscall(SB),NOSPLIT,$0-32
 	MOVSL
 	MOVSL
 	INT	$64
-	MOVL	AX, r1+20(SP)
-	MOVL	$0, r2+24(SP)
+	MOVL	AX, r1+16(FP)
+	MOVL	$0, r2+20(FP)
 	CMPL	AX, $-1
 	JNE	ok3
 
@@ -44,7 +44,7 @@ ok3:
 	LEAL	runtime·emptystring(SB), SI	
 	
 copyresult3:
-	LEAL	err+28(SP), DI
+	LEAL	err+24(FP), DI
 
 	CLD
 	MOVSL
@@ -67,8 +67,8 @@ TEXT	·Syscall6(SB),NOSPLIT,$0-44
 	MOVSL
 	MOVSL
 	INT	$64
-	MOVL	AX, r1+32(SP)
-	MOVL	$0, r2+36(SP)
+	MOVL	AX, r1+28(FP)
+	MOVL	$0, r2+32(FP)
 	CMPL	AX, $-1
 	JNE	ok4
 	
@@ -82,7 +82,7 @@ ok4:
 	LEAL	runtime·emptystring(SB), SI
 	
 copyresult4:
-	LEAL	err+40(SP), DI
+	LEAL	err+36(FP), DI
 
 	CLD
 	MOVSL
@@ -101,9 +101,9 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-28
 	MOVSL
 	MOVSL
 	INT	$64
-	MOVL	AX, r1+20(SP)
-	MOVL	AX, r2+24(SP)
-	MOVL	AX, err+28(SP)
+	MOVL	AX, r1+16(FP)
+	MOVL	AX, r2+20(FP)
+	MOVL	AX, err+24(FP)
 	RET
 
 TEXT	·RawSyscall6(SB),NOSPLIT,$0-40
@@ -119,17 +119,17 @@ TEXT	·RawSyscall6(SB),NOSPLIT,$0-40
 	MOVSL
 	MOVSL
 	INT	$64
-	MOVL	AX, r1+32(SP)
-	MOVL	AX, r2+36(SP)
-	MOVL	AX, err+40(SP)		
+	MOVL	AX, r1+28(FP)
+	MOVL	AX, r2+32(FP)
+	MOVL	AX, err+36(FP)
 	RET
 
 #define SYS_SEEK 39	/* from zsysnum_plan9_386.go */
 
 //func seek(placeholder uintptr, fd int, offset int64, whence int) (newoffset int64, err string)
 TEXT ·seek(SB),NOSPLIT,$0-36
-	LEAL	newoffset+24(SP), AX
-	MOVL	AX, placeholder+4(SP)
+	LEAL	newoffset+20(FP), AX
+	MOVL	AX, placeholder+0(FP)
 	
 	MOVL	$SYS_SEEK, AX	// syscall entry
 	INT	$64
@@ -149,7 +149,7 @@ ok6:
 	LEAL	runtime·emptystring(SB), SI
 	
 copyresult6:
-	LEAL	err+32(SP), DI
+	LEAL	err+28(FP), DI
 
 	CLD
 	MOVSL

src/syscall/asm_plan9_amd64.s

@@ -28,8 +28,8 @@ TEXT	·Syscall(SB),NOSPLIT,$0-64
 	MOVSQ
 	MOVSQ
 	SYSCALL
-	MOVQ	AX, r1+40(SP)
-	MOVQ	$0, r2+48(SP)
+	MOVQ	AX, r1+32(FP)
+	MOVQ	$0, r2+40(FP)
 	CMPL	AX, $-1
 	JNE	ok3
 
@@ -43,7 +43,7 @@ ok3:
 	LEAQ	runtime·emptystring(SB), SI	
 	
 copyresult3:
-	LEAQ	err+56(SP), DI
+	LEAQ	err+48(FP), DI
 
 	CLD
 	MOVSQ
@@ -66,8 +66,8 @@ TEXT	·Syscall6(SB),NOSPLIT,$0-88
 	MOVSQ
 	MOVSQ
 	SYSCALL
-	MOVQ	AX, r1+64(SP)
-	MOVQ	$0, r2+72(SP)
+	MOVQ	AX, r1+56(FP)
+	MOVQ	$0, r2+64(FP)
 	CMPL	AX, $-1
 	JNE	ok4
 	
@@ -81,7 +81,7 @@ ok4:
 	LEAQ	runtime·emptystring(SB), SI
 	
 copyresult4:
-	LEAQ	err+80(SP), DI
+	LEAQ	err+72(FP), DI
 
 	CLD
 	MOVSQ
@@ -100,9 +100,9 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-56
 	MOVSQ
 	MOVSQ
 	SYSCALL
-	MOVQ	AX, r1+40(SP)
-	MOVQ	AX, r2+48(SP)
-	MOVQ	AX, err+56(SP)
+	MOVQ	AX, r1+32(FP)
+	MOVQ	AX, r2+40(FP)
+	MOVQ	AX, err+48(FP)
 	RET
 
 TEXT	·RawSyscall6(SB),NOSPLIT,$0-80
@@ -118,24 +118,24 @@ TEXT	·RawSyscall6(SB),NOSPLIT,$0-80
 	MOVSQ
 	MOVSQ
 	SYSCALL
-	MOVQ	AX, r1+64(SP)
-	MOVQ	AX, r2+72(SP)
-	MOVQ	AX, err+80(SP)		
+	MOVQ	AX, r1+56(FP)
+	MOVQ	AX, r2+64(FP)
+	MOVQ	AX, err+72(FP)
 	RET
 
 #define SYS_SEEK 39	/* from zsysnum_plan9_amd64.go */
 
 //func seek(placeholder uintptr, fd int, offset int64, whence int) (newoffset int64, err string)
 TEXT ·seek(SB),NOSPLIT,$0-56
-	LEAQ	newoffset+40(SP), AX
-	MOVQ	AX, placeholder+8(SP)
+	LEAQ	newoffset+32(FP), AX
+	MOVQ	AX, placeholder+0(FP)
 	
 	MOVQ	$SYS_SEEK, BP	// syscall entry
 	SYSCALL
 	
 	CMPL	AX, $-1
 	JNE	ok6
-	MOVQ	$-1, newoffset+40(SP)
+	MOVQ	$-1, newoffset+32(FP)
 	
 	SUBQ	$16, SP
 	CALL	syscall·errstr(SB)
@@ -147,7 +147,7 @@ ok6:
 	LEAQ	runtime·emptystring(SB), SI
 	
 copyresult6:
-	LEAQ	err+48(SP), DI
+	LEAQ	err+40(FP), DI
 
 	CLD
 	MOVSQ