cmd/6c, cmd/6g: add flag to support large-model code generation

Added the -pic flag to 6c and 6g to avoid assembler instructions that
cannot use RIP-relative adressing. This is needed to support the -shared mode
in 6l.

See also:
https://golang.org/cl/6926049
https://golang.org/cl/6822078

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7064048

src/cmd/6c/sgen.c

@@ -126,7 +126,10 @@ xcom(Node *n)
 		break;
 
 	case ONAME:
-		n->addable = 10;
+		if(flag_largemodel)
+			n->addable = 9;
+		else
+			n->addable = 10;
 		if(n->class == CPARAM || n->class == CAUTO)
 			n->addable = 11;
 		break;

src/cmd/6g/cgen.c

@@ -737,8 +737,12 @@ agenr(Node *n, Node *a, Node *res)
 			regalloc(&n3, types[tptr], res);
 			p1 = gins(ALEAQ, N, &n3);
 			datastring(nl->val.u.sval->s, nl->val.u.sval->len, &p1->from);
-			p1->from.scale = 1;
-			p1->from.index = n2.val.u.reg;
+			if(flag_largemodel) {
+				gins(AADDQ, &n2, &n3);
+			} else {
+				p1->from.scale = 1;
+				p1->from.index = n2.val.u.reg;
+			}
 			goto indexdone;
 		}
 

src/cmd/6g/ggen.c

@@ -59,6 +59,7 @@ ginscall(Node *f, int proc)
 {
 	Prog *p;
 	Node reg, con;
+	Node r1;
 
 	switch(proc) {
 	default:
@@ -76,7 +77,14 @@ ginscall(Node *f, int proc)
 	case 1:	// call in new proc (go)
 	case 2:	// deferred call (defer)
 		nodreg(&reg, types[TINT64], D_CX);
-		gins(APUSHQ, f, N);
+		if(flag_largemodel) {
+			regalloc(&r1, f->type, f);
+			gmove(f, &r1);
+			gins(APUSHQ, &r1, N);
+			regfree(&r1);
+		} else {
+			gins(APUSHQ, f, N);
+		}
 		nodconst(&con, types[TINT32], argsize(f->type));
 		gins(APUSHQ, &con, N);
 		if(proc == 1)

src/cmd/6g/gsubr.c

@@ -554,6 +554,10 @@ ismem(Node *n)
 	case ONAME:
 	case OPARAM:
 		return 1;
+	case OADDR:
+		if(flag_largemodel)
+			return 1;
+		break;
 	}
 	return 0;
 }

src/cmd/cc/cc.h

@@ -528,6 +528,7 @@ EXTERN	int	packflg;
 EXTERN	int	fproundflg;
 EXTERN	int	textflag;
 EXTERN	int	dataflag;
+EXTERN	int	flag_largemodel;
 EXTERN	int	ncontin;
 EXTERN	int	canreach;
 EXTERN	int	warnreach;

src/cmd/cc/lex.c

@@ -174,6 +174,8 @@ main(int argc, char *argv[])
 	flagcount("t", "debug code generation", &debug['t']);
 	flagcount("w", "enable warnings", &debug['w']);
 	flagcount("v", "increase debug verbosity", &debug['v']);	
+	if(thechar == '6')
+		flagcount("largemodel", "generate code that assumes a large memory model", &flag_largemodel);
 	
 	flagparse(&argc, &argv, usage);
 

src/cmd/gc/go.h

@@ -941,6 +941,7 @@ EXTERN	int	compiling_runtime;
 EXTERN	int	compiling_wrappers;
 EXTERN	int	pure_go;
 EXTERN	int	flag_race;
+EXTERN	int	flag_largemodel;
 
 EXTERN	int	nointerface;
 EXTERN	int	fieldtrack_enabled;

src/cmd/gc/lex.c

@@ -257,6 +257,8 @@ main(int argc, char *argv[])
 	flagcount("w", "debug type checking", &debug['w']);
 	flagcount("x", "debug lexer", &debug['x']);
 	flagcount("y", "debug declarations in canned imports (with -d)", &debug['y']);
+	if(thechar == '6')
+		flagcount("largemodel", "generate code that assumes a large memory model", &flag_largemodel);
 
 	flagparse(&argc, &argv, usage);
 

src/make.bash

@@ -23,6 +23,9 @@
 # GO_LDFLAGS: Additional 5l/6l/8l arguments to use when
 # building the commands.
 #
+# GO_CCFLAGS: Additional 5c/6c/8c arguments to use when
+# building.
+#
 # CGO_ENABLED: Controls cgo usage during the build. Set it to 1
 # to include all cgo related files, .c and .go file with "cgo"
 # build directive, in the build. Set it to 0 to ignore them.
@@ -129,12 +132,12 @@ echo
 if [ "$GOHOSTARCH" != "$GOARCH" -o "$GOHOSTOS" != "$GOOS" ]; then
 	echo "# Building packages and commands for host, $GOHOSTOS/$GOHOSTARCH."
 	GOOS=$GOHOSTOS GOARCH=$GOHOSTARCH \
-		"$GOTOOLDIR"/go_bootstrap install -gcflags "$GO_GCFLAGS" -ldflags "$GO_LDFLAGS" -v std
+		"$GOTOOLDIR"/go_bootstrap install -ccflags "$GO_CCFLAGS" -gcflags "$GO_GCFLAGS" -ldflags "$GO_LDFLAGS" -v std
 	echo
 fi
 
 echo "# Building packages and commands for $GOOS/$GOARCH."
-"$GOTOOLDIR"/go_bootstrap install -gcflags "$GO_GCFLAGS" -ldflags "$GO_LDFLAGS" -v std
+"$GOTOOLDIR"/go_bootstrap install $GO_FLAGS -ccflags "$GO_CCFLAGS" -gcflags "$GO_GCFLAGS" -ldflags "$GO_LDFLAGS" -v std
 echo
 
 rm -f "$GOTOOLDIR"/go_bootstrap