runtime: split plan9 and solaris's m fields into new embedded mOS type

Reduces the size of m by ~8% on linux/amd64 (1040 bytes -> 960 bytes).

There are also windows-specific fields, but they're currently
referenced in OS-independent source files (but only when
GOOS=="windows").

Change-Id: I13e1471ff585ccced1271f74209f8ed6df14c202
Reviewed-on: https://go-review.googlesource.com/16173
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/os_darwin.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 func bsdthread_create(stk, arg unsafe.Pointer, fn uintptr) int32
 func bsdthread_register() int32
 

src/runtime/os_dragonfly.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 //go:noescape
 func lwp_create(param *lwpparams) int32
 

src/runtime/os_freebsd.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 //go:noescape
 func thr_new(param *thrparam, size int32)
 

src/runtime/os_linux.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 //go:noescape
 func futex(addr unsafe.Pointer, op int32, val uint32, ts, addr2 unsafe.Pointer, val3 uint32) int32
 

src/runtime/os_nacl.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 func nacl_exception_stack(p uintptr, size int32) int32
 func nacl_exception_handler(fn uintptr, arg unsafe.Pointer) int32
 func nacl_sem_create(flag int32) int32

src/runtime/os_netbsd.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 //go:noescape
 func setitimer(mode int32, new, old *itimerval)
 

src/runtime/os_openbsd.go

@@ -4,6 +4,8 @@
 
 package runtime
 
+type mOS struct{}
+
 //go:noescape
 func setitimer(mode int32, new, old *itimerval)
 

src/runtime/os_plan9.go

@@ -6,6 +6,11 @@ package runtime
 
 import "unsafe"
 
+type mOS struct {
+	notesig *int8
+	errstr  *byte
+}
+
 func closefd(fd int32) int32
 
 //go:noescape

src/runtime/os_solaris.go

@@ -6,6 +6,24 @@ package runtime
 
 import "unsafe"
 
+type mts struct {
+	tv_sec  int64
+	tv_nsec int64
+}
+
+type mscratch struct {
+	v [6]uintptr
+}
+
+type mOS struct {
+	perrno *int32 // pointer to tls errno
+	// these are here because they are too large to be on the stack
+	// of low-level NOSPLIT functions.
+	//LibCall       libcall;
+	ts      mts
+	scratch mscratch
+}
+
 type libcFunc uintptr
 
 var asmsysvicall6 libcFunc

src/runtime/os_windows.go

@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+type mOS struct{}
+
 type stdFunction *byte
 
 //go:linkname os_sigpipe os.sigpipe

src/runtime/runtime2.go

@@ -269,15 +269,6 @@ type g struct {
 	gcAssistBytes int64
 }
 
-type mts struct {
-	tv_sec  int64
-	tv_nsec int64
-}
-
-type mscratch struct {
-	v [6]uintptr
-}
-
 type m struct {
 	g0      *g     // goroutine with scheduling stack
 	morebuf gobuf  // gobuf arg to morestack
@@ -343,18 +334,7 @@ type m struct {
 	libcallg  guintptr
 	syscall   libcall // stores syscall parameters on windows
 	//#endif
-	//#ifdef GOOS_solaris
+	mOS
-	perrno *int32 // pointer to tls errno
-	// these are here because they are too large to be on the stack
-	// of low-level NOSPLIT functions.
-	//LibCall	libcall;
-	ts      mts
-	scratch mscratch
-	//#endif
-	//#ifdef GOOS_plan9
-	notesig *int8
-	errstr  *byte
-	//#endif
 }
 
 type p struct {

src/runtime/sys_plan9_386.s

@@ -238,7 +238,7 @@ TEXT runtime·errstr(SB),NOSPLIT,$8-8
 	get_tls(AX)
 	MOVL	g(AX), BX
 	MOVL	g_m(BX), BX
-	MOVL	m_errstr(BX), CX
+	MOVL	(m_mOS+mOS_errstr)(BX), CX
 	MOVL	CX, 0(SP)
 	MOVL	$ERRMAX, 4(SP)
 	CALL	errstr<>(SB)

src/runtime/sys_plan9_amd64.s

@@ -243,7 +243,7 @@ TEXT runtime·errstr(SB),NOSPLIT,$16-16
 	get_tls(AX)
 	MOVQ	g(AX), BX
 	MOVQ	g_m(BX), BX
-	MOVQ	m_errstr(BX), CX
+	MOVQ	(m_mOS+mOS_errstr)(BX), CX
 	MOVQ	CX, 0(SP)
 	MOVQ	$ERRMAX, 8(SP)
 	CALL	errstr<>(SB)

src/runtime/sys_solaris_amd64.s

@@ -26,7 +26,7 @@ TEXT runtime·miniterrno(SB),NOSPLIT,$0
 	get_tls(CX)
 	MOVQ	g(CX), BX
 	MOVQ	g_m(BX), BX
-	MOVQ	AX,	m_perrno(BX)
+	MOVQ	AX,	(m_mOS+mOS_perrno)(BX)
 	RET
 
 // int64 runtime·nanotime1(void);
@@ -81,7 +81,7 @@ TEXT runtime·asmsysvicall6(SB),NOSPLIT,$0
 	get_tls(CX)
 	MOVQ	g(CX), BX
 	MOVQ	g_m(BX), BX
-	MOVQ	m_perrno(BX), DX
+	MOVQ	(m_mOS+mOS_perrno)(BX), DX
 	CMPQ	DX, $0
 	JEQ	skiperrno1
 	MOVL	$0, 0(DX)
@@ -109,7 +109,7 @@ skipargs:
 	get_tls(CX)
 	MOVQ	g(CX), BX
 	MOVQ	g_m(BX), BX
-	MOVQ	m_perrno(BX), AX
+	MOVQ	(m_mOS+mOS_perrno)(BX), AX
 	CMPQ	AX, $0
 	JEQ	skiperrno2
 	MOVL	0(AX), AX
@@ -196,7 +196,7 @@ allgood:
 	MOVQ    R10, 176(SP)
 
 	// save m->scratch
-	LEAQ	m_scratch(BP), R11
+	LEAQ	(m_mOS+mOS_scratch)(BP), R11
 	MOVQ	0(R11), R10
 	MOVQ	R10, 112(SP)
 	MOVQ	8(R11), R10
@@ -211,7 +211,7 @@ allgood:
 	MOVQ	R10, 152(SP)
 
 	// save errno, it might be EINTR; stuff we do here might reset it.
-	MOVQ	m_perrno(BP), R10
+	MOVQ	(m_mOS+mOS_perrno)(BP), R10
 	MOVL	0(R10), R10
 	MOVQ	R10, 160(SP)
 
@@ -244,7 +244,7 @@ allgood:
 	MOVQ    R10, libcall_r2(R11)
 
 	// restore scratch
-	LEAQ	m_scratch(BP), R11
+	LEAQ	(m_mOS+mOS_scratch)(BP), R11
 	MOVQ	112(SP), R10
 	MOVQ	R10, 0(R11)
 	MOVQ	120(SP), R10
@@ -259,7 +259,7 @@ allgood:
 	MOVQ	R10, 40(R11)
 
 	// restore errno
-	MOVQ	m_perrno(BP), R11
+	MOVQ	(m_mOS+mOS_perrno)(BP), R11
 	MOVQ	160(SP), R10
 	MOVL	R10, 0(R11)