fix issue 798

cannot allocate an audomatic temp
while real registers are allocated.
there is a chance that the automatic
will be allocated to one of the
allocated registers. the fix is to
not registerize such variables.

R=rsc
CC=golang-dev
https://golang.org/cl/1202042

src/cmd/5g/gsubr.c

@@ -197,6 +197,12 @@ afunclit(Addr *a)
 	}
 }
 
+int32
+anyregalloc(void)
+{
+	return 0;
+}
+
 /*
  * allocate register of type t, leave in n.
  * if o != N, o is desired fixed register.

src/cmd/6g/gg.h

@@ -28,6 +28,7 @@ struct	Addr
 	uchar	index;
 	uchar	etype;
 	uchar	scale;	/* doubles as width in DATA op */
+	uchar	pun;	/* dont register variable */
 };
 #define	A	((Addr*)0)
 

src/cmd/6g/gsubr.c

@@ -238,6 +238,23 @@ gclean(void)
 			yyerror("reg %R left allocated\n", i);
 }
 
+int32
+anyregalloc(void)
+{
+	int i, j;
+
+	for(i=D_AL; i<=D_DI; i++) {
+		if(reg[i] == 0)
+			goto ok;
+		for(j=0; j<nelem(resvd); j++)
+			if(resvd[j] == i)
+				goto ok;
+		return 1;
+	ok:;
+	}
+	return 0;
+}
+
 /*
  * allocate register of type t, leave in n.
  * if o != N, o is desired fixed register.
@@ -982,6 +999,7 @@ naddr(Node *n, Addr *a, int canemitcode)
 			a->width = n->type->width;
 			a->gotype = ngotype(n);
 		}
+		a->pun = n->pun;
 		a->offset = n->xoffset;
 		a->sym = n->sym;
 		if(a->sym == S)

src/cmd/6g/reg.c

@@ -879,6 +879,8 @@ mkvar(Reg *r, Adr *a)
 			}
 		}
 	}
+	if(a->pun)
+		flag = 1;
 
 	switch(et) {
 	case 0:

src/cmd/8g/gg.h

@@ -30,6 +30,7 @@ struct	Addr
 	uchar	index;
 	uchar	etype;
 	uchar	scale;	/* doubles as width in DATA op */
+	uchar	pun;	/* dont register variable */
 };
 #define	A	((Addr*)0)
 

src/cmd/8g/gsubr.c

@@ -710,6 +710,23 @@ gclean(void)
 			yyerror("reg %R left allocated at %lux", i, regpc[i]);
 }
 
+int32
+anyregalloc(void)
+{
+	int i, j;
+
+	for(i=D_AL; i<=D_DI; i++) {
+		if(reg[i] == 0)
+			goto ok;
+		for(j=0; j<nelem(resvd); j++)
+			if(resvd[j] == i)
+				goto ok;
+		return 1;
+	ok:;
+	}
+	return 0;
+}
+
 /*
  * allocate register of type t, leave in n.
  * if o != N, o is desired fixed register.
@@ -1692,6 +1709,7 @@ naddr(Node *n, Addr *a, int canemitcode)
 			a->width = n->type->width;
 			a->gotype = ngotype(n);
 		}
+		a->pun = n->pun;
 		a->offset = n->xoffset;
 		a->sym = n->sym;
 		if(a->sym == S)

src/cmd/8g/reg.c

@@ -794,6 +794,8 @@ mkvar(Reg *r, Adr *a)
 			}
 		}
 	}
+	if(a->pun)
+		flag = 1;
 
 	switch(et) {
 	case 0:

src/cmd/gc/gen.c

@@ -663,4 +663,5 @@ tempname(Node *n, Type *t)
 	stksize += w;
 	stksize = rnd(stksize, w);
 	n->xoffset = -stksize;
+	n->pun = anyregalloc();
 }

src/cmd/gc/go.h

@@ -215,6 +215,7 @@ struct	Node
 	uchar	used;
 	uchar	oldref;
 	uchar	isddd;
+	uchar	pun;		// dont registerize variable ONAME
 
 	// most nodes
 	Node*	left;
@@ -1241,3 +1242,4 @@ int	duintptr(Sym *s, int off, uint64 v);
 int	duintxx(Sym *s, int off, uint64 v, int wid);
 void	genembedtramp(Type*, Type*, Sym*);
 int	gen_as_init(Node*);
+int	anyregalloc();