From b0283611e487afe664e88ddad98cbd4b6f46a0b0 Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Thu, 20 May 2010 17:31:28 -0700
Subject: [PATCH] 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 |  6 ++++++
 src/cmd/6g/gg.h    |  1 +
 src/cmd/6g/gsubr.c | 18 ++++++++++++++++++
 src/cmd/6g/reg.c   |  2 ++
 src/cmd/8g/gg.h    |  1 +
 src/cmd/8g/gsubr.c | 18 ++++++++++++++++++
 src/cmd/8g/reg.c   |  2 ++
 src/cmd/gc/gen.c   |  1 +
 src/cmd/gc/go.h    |  2 ++
 9 files changed, 51 insertions(+)

diff --git a/src/cmd/5g/gsubr.c b/src/cmd/5g/gsubr.c
index ef78157472..ea6ab1d70b 100644
--- a/src/cmd/5g/gsubr.c
+++ b/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.
diff --git a/src/cmd/6g/gg.h b/src/cmd/6g/gg.h
index 875c773588..353a86dcd8 100644
--- a/src/cmd/6g/gg.h
+++ b/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)
 
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index e9ad6c0946..1c11b14aeb 100644
--- a/src/cmd/6g/gsubr.c
+++ b/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)
diff --git a/src/cmd/6g/reg.c b/src/cmd/6g/reg.c
index 10a00b38df..e92740e04b 100644
--- a/src/cmd/6g/reg.c
+++ b/src/cmd/6g/reg.c
@@ -879,6 +879,8 @@ mkvar(Reg *r, Adr *a)
 			}
 		}
 	}
+	if(a->pun)
+		flag = 1;
 
 	switch(et) {
 	case 0:
diff --git a/src/cmd/8g/gg.h b/src/cmd/8g/gg.h
index a00d69711c..57cd1b56b5 100644
--- a/src/cmd/8g/gg.h
+++ b/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)
 
diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index 27fec96a73..3e85b7e30e 100644
--- a/src/cmd/8g/gsubr.c
+++ b/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)
diff --git a/src/cmd/8g/reg.c b/src/cmd/8g/reg.c
index e23205c68f..3e57916c73 100644
--- a/src/cmd/8g/reg.c
+++ b/src/cmd/8g/reg.c
@@ -794,6 +794,8 @@ mkvar(Reg *r, Adr *a)
 			}
 		}
 	}
+	if(a->pun)
+		flag = 1;
 
 	switch(et) {
 	case 0:
diff --git a/src/cmd/gc/gen.c b/src/cmd/gc/gen.c
index 437d41fcf7..ec41d9b8eb 100644
--- a/src/cmd/gc/gen.c
+++ b/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();
 }
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 3051ebe2ba..5aa95eee3b 100644
--- a/src/cmd/gc/go.h
+++ b/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();