defer

R=r
OCL=23592
CL=23592

src/cmd/6g/gen.c

@@ -26,6 +26,22 @@ if(newproc == N) {
 	newproc->ullman = 1;
 }
 
+if(deferproc == N) {
+	deferproc = nod(ONAME, N, N);
+	deferproc->sym = pkglookup("deferproc", "sys");
+	deferproc->class = PEXTERN;
+	deferproc->addable = 1;
+	deferproc->ullman = 1;
+}
+
+if(deferreturn == N) {
+	deferreturn = nod(ONAME, N, N);
+	deferreturn->sym = pkglookup("deferreturn", "sys");
+	deferreturn->class = PEXTERN;
+	deferreturn->addable = 1;
+	deferreturn->ullman = 1;
+}
+
 if(throwindex == N) {
 	throwindex = nod(ONAME, N, N);
 	throwindex->sym = pkglookup("throwindex", "sys");
@@ -63,6 +79,7 @@ if(throwreturn == N) {
 		}
 	}
 
+	hasdefer = 0;
 	walk(curfn);
 	if(nerrors != 0)
 		goto ret;
@@ -90,6 +107,8 @@ if(throwreturn == N) {
 		gins(ACALL, N, throwreturn);
 	}
 
+	if(hasdefer)
+		gins(ACALL, N, deferreturn);
 	pc->as = ARET;	// overwrite AEND
 	pc->lineno = lineno;
 
@@ -343,7 +362,11 @@ loop:
 		break;
 
 	case OPROC:
-		cgen_proc(n);
+		cgen_proc(n, 1);
+		break;
+
+	case ODEFER:
+		cgen_proc(n, 2);
 		break;
 
 	case ORETURN:
@@ -683,19 +706,26 @@ argsize(Type *t)
 /*
  * generate:
  *	call f
- * if proc, generate:
- *	push f
- *	push argsize
- *	call newproc
- *	pop
- *	pop
+ *	proc=0	normal call
+ *	proc=1	goroutine run in new proc
+ *	proc=2	defer call save away stack
  */
 void
 ginscall(Node *f, int proc)
 {
 	Node reg, con;
 
-	if(proc) {
+	switch(proc) {
+	default:
+		fatal("ginscall: bad proc %d", proc);
+		break;
+
+	case 0:	// normal call
+		gins(ACALL, N, f);
+		break;
+
+	case 1:	// call in new proc (go)
+	case 2:	// defered call (defer)
 		nodreg(&reg, types[TINT64], D_AX);
 		if(f->op != OREGISTER) {
 			gins(ALEAQ, f, &reg);
@@ -704,12 +734,14 @@ ginscall(Node *f, int proc)
 			gins(APUSHQ, f, N);
 		nodconst(&con, types[TINT32], argsize(f->type));
 		gins(APUSHQ, &con, N);
+		if(proc == 1)
 			gins(ACALL, N, newproc);
+		else
+			gins(ACALL, N, deferproc);
 		gins(APOPQ, N, &reg);
 		gins(APOPQ, N, &reg);
-		return;
+		break;
 	}
-	gins(ACALL, N, f);
 }
 
 /*
@@ -767,6 +799,9 @@ cgen_callinter(Node *n, Node *res, int proc)
 
 /*
  * generate call to non-interface method
+ *	proc=0	normal call
+ *	proc=1	goroutine run in new proc
+ *	proc=2	defer call save away stack
  */
 void
 cgen_callmeth(Node *n, int proc)
@@ -791,7 +826,9 @@ cgen_callmeth(Node *n, int proc)
 
 /*
  * generate function call;
- * if proc, run call in new proc.
+ *	proc=0	normal call
+ *	proc=1	goroutine run in new proc
+ *	proc=2	defer call save away stack
  */
 void
 cgen_call(Node *n, int proc)
@@ -851,22 +888,22 @@ ret:
  * generate code to start new proc running call n.
  */
 void
-cgen_proc(Node *n)
+cgen_proc(Node *n, int proc)
 {
 	switch(n->left->op) {
 	default:
 		fatal("cgen_proc: unknown call %O", n->left->op);
 
 	case OCALLMETH:
-		cgen_callmeth(n->left, 1);
+		cgen_callmeth(n->left, proc);
 		break;
 
 	case OCALLINTER:
-		cgen_callinter(n->left, N, 1);
+		cgen_callinter(n->left, N, proc);
 		break;
 
 	case OCALL:
-		cgen_call(n->left, 1);
+		cgen_call(n->left, proc);
 		break;
 	}
 
@@ -947,6 +984,8 @@ void
 cgen_ret(Node *n)
 {
 	gen(n->left, L);	// copy out args
+	if(hasdefer)
+		gins(ACALL, N, deferreturn);
 	gins(ARET, N, N);
 }
 

src/cmd/6g/gg.h

@@ -116,6 +116,8 @@ EXTERN	Label*	labellist;
 EXTERN	Label*	findlab(Sym*);
 EXTERN	Node*	curfn;
 EXTERN	Node*	newproc;
+EXTERN	Node*	deferproc;
+EXTERN	Node*	deferreturn;
 EXTERN	Node*	throwindex;
 EXTERN	Node*	throwreturn;
 
@@ -151,7 +153,7 @@ void	cgen_ret(Node*);
 void	cgen_call(Node*, int);
 void	cgen_callmeth(Node*, int);
 void	cgen_callinter(Node*, Node*, int);
-void	cgen_proc(Node*);
+void	cgen_proc(Node*, int);
 void	cgen_callret(Node*, Node*);
 void	cgen_div(int, Node*, Node*, Node*);
 void	cgen_bmul(int, Node*, Node*, Node*);

src/cmd/gc/go.h

@@ -291,7 +291,7 @@ enum
 	ODOT, ODOTPTR, ODOTMETH, ODOTINTER,
 	ODCLFUNC, ODCLFIELD, ODCLARG,
 	OLIST, OCMP, OPTR, OARRAY, ORANGE,
-	ORETURN, OFOR, OIF, OSWITCH,
+	ORETURN, OFOR, OIF, OSWITCH, ODEFER,
 	OAS, OASOP, OCASE, OXCASE, OFALL, OXFALL,
 	OGOTO, OPROC, OMAKE, ONEW, OEMPTY, OSELECT,
 	OLEN, OCAP, OPANIC, OPANICN, OPRINT, OPRINTN, OTYPEOF,
@@ -498,6 +498,7 @@ EXTERN	int32	stksize;		// stack size for current frame
 EXTERN	int32	initstksize;		// stack size for init function
 EXTERN	ushort	blockgen;		// max block number
 EXTERN	ushort	block;			// current block number
+EXTERN	int	hasdefer;		// flag that curfn has defer statetment
 
 EXTERN	Node*	retnil;
 EXTERN	Node*	fskel;

src/cmd/gc/go.y

@@ -15,7 +15,7 @@
 %token	<val>		LLITERAL
 %token	<lint>		LASOP
 %token	<sym>		LNAME LBASETYPE LATYPE LPACK LACONST
-%token	<sym>		LPACKAGE LIMPORT LEXPORT
+%token	<sym>		LPACKAGE LIMPORT LDEFER
 %token	<sym>		LMAP LCHAN LINTERFACE LFUNC LSTRUCT
 %token	<sym>		LCOLAS LFALL LRETURN LDDD
 %token	<sym>		LLEN LCAP LTYPEOF LPANIC LPANICN LPRINT LPRINTN
@@ -504,6 +504,11 @@ semi_stmt:
 		$$ = nod(OCALL, $2, $4);
 		$$ = nod(OPROC, $$, N);
 	}
+|	LDEFER pexpr '(' oexpr_list ')'
+	{
+		$$ = nod(OCALL, $2, $4);
+		$$ = nod(ODEFER, $$, N);
+	}
 |	LGOTO new_name
 	{
 		$$ = nod(OGOTO, $2, N);

src/cmd/gc/lex.c

@@ -1056,7 +1056,7 @@ static	struct
 	"continue",	LCONTINUE,	Txxx,
 	"default",	LDEFAULT,	Txxx,
 	"else",		LELSE,		Txxx,
-	"export",	LEXPORT,	Txxx,
+	"defer",	LDEFER,		Txxx,
 	"fallthrough",	LFALL,		Txxx,
 	"false",	LFALSE,		Txxx,
 	"for",		LFOR,		Txxx,
@@ -1275,7 +1275,7 @@ struct
 	LPRINT,		"PRINT",
 	LPACKAGE,	"PACKAGE",
 	LIMPORT,	"IMPORT",
-	LEXPORT,	"EXPORT",
+	LDEFER,		"DEFER",
 	LPANIC,		"PANIC",
 };
 

src/cmd/gc/subr.c

@@ -641,11 +641,12 @@ opnames[] =
 	[ODCLARG]	= "DCLARG",
 	[ODCLFIELD]	= "DCLFIELD",
 	[ODCLFUNC]	= "DCLFUNC",
+	[ODEFER]	= "DEFER",
 	[ODIV]		= "DIV",
-	[ODOT]		= "DOT",
-	[ODOTPTR]	= "DOTPTR",
-	[ODOTMETH]	= "DOTMETH",
 	[ODOTINTER]	= "DOTINTER",
+	[ODOTMETH]	= "DOTMETH",
+	[ODOTPTR]	= "DOTPTR",
+	[ODOT]		= "DOT",
 	[OEMPTY]	= "EMPTY",
 	[OEND]		= "END",
 	[OEQ]		= "EQ",

src/cmd/gc/walk.c

@@ -145,6 +145,7 @@ loop:
 	case OXFALL:
 	case ORETURN:
 	case OPROC:
+	case ODEFER:
 		walktype(n, Etop);
 		break;
 	}
@@ -342,6 +343,8 @@ loop:
 		walkstate(n->nelse);
 		goto ret;
 
+	case ODEFER:
+		hasdefer = 1;
 	case OPROC:
 		if(top != Etop)
 			goto nottop;

src/runtime/proc.c

@@ -171,7 +171,7 @@ sys·newproc(int32 siz, byte* fn, byte* arg0)
 
 	if((newg = gfget()) != nil){
 		newg->status = Gwaiting;
-	}else{
+	} else {
 		newg = malg(4096);
 		newg->status = Gwaiting;
 		newg->alllink = allg;
@@ -204,6 +204,41 @@ sys·newproc(int32 siz, byte* fn, byte* arg0)
 //printf(" goid=%d\n", newg->goid);
 }
 
+void
+sys·deferproc(int32 siz, byte* fn, byte* arg0)
+{
+	Defer *d;
+
+	d = mal(sizeof(*d) + siz - sizeof(d->args));
+	d->fn = fn;
+	d->sp = (byte*)&arg0;
+	d->siz = siz;
+	mcpy(d->args, d->sp, d->siz);
+
+	d->link = g->defer;
+	g->defer = d;
+}
+
+void
+sys·deferreturn(int32 arg0)
+{
+	// warning: jmpdefer knows the frame size
+	// of this routine. dont change anything
+	// that might change the frame size
+	Defer *d;
+	byte *sp;
+
+	d = g->defer;
+	if(d == nil)
+		return;
+	sp = (byte*)&arg0;
+	if(d->sp != sp)
+		return;
+	mcpy(d->sp, d->args, d->siz);
+	g->defer = d->link;
+	jmpdefer(d->fn);
+}
+
 void
 tracebackothers(G *me)
 {

src/runtime/rt0_amd64.s

@@ -120,7 +120,7 @@ TEXT setspgoto(SB), 7, $0
 //	if(*val == old){
 //		*val = new;
 //		return 1;
-//	}else
+//	} else
 //		return 0;
 TEXT cas(SB), 7, $0
 	MOVQ	8(SP), BX
@@ -133,3 +133,13 @@ TEXT cas(SB), 7, $0
 	RET
 	MOVL	$1, AX
 	RET
+
+// void jmpdefer(byte*);
+// 1. pop the caller
+// 2. sub 5 bytes from the callers return
+// 3. jmp to the argument
+TEXT jmpdefer(SB), 7, $0
+	MOVQ	8(SP), AX	// function
+	ADDQ	$(8+56), SP	// pop saved PC and callers frame
+	SUBQ	$5, (SP)	// reposition his return address
+	JMP	AX		// and goto function

src/runtime/runtime.h

@@ -52,6 +52,7 @@ typedef	struct	SigTab		SigTab;
 typedef	struct	MCache		MCache;
 typedef	struct	Iface		Iface;
 typedef	struct	Itype		Itype;
+typedef	struct	Defer		Defer;
 
 /*
  * per cpu declaration
@@ -128,6 +129,7 @@ struct	G
 {
 	byte*	stackguard;	// must not move
 	byte*	stackbase;	// must not move
+	Defer*	defer;		// must not move
 	byte*	stack0;		// first stack segment
 	Gobuf	sched;
 	G*	alllink;	// on allg
@@ -235,6 +237,18 @@ enum
 	Amax
 };
 
+/*
+ * defered subroutine calls
+ */
+struct Defer
+{
+	int32	siz;
+	byte*	sp;
+	byte*	fn;
+	Defer*	link;
+	byte	args[8];	// padded to actual size
+};
+
 /*
  * external data
  */
@@ -286,6 +300,7 @@ int32	write(int32, void*, int32);
 void	close(int32);
 int32	fstat(int32, void*);
 bool	cas(uint32*, uint32, uint32);
+void	jmpdefer(byte*);
 void	exit1(int32);
 void	ready(G*);
 byte*	getenv(int8*);