cmd/5g, cmd/6g: pass the full torture test.

The patch adds more cases to agenr to allocate registers later,
and makes 6g generate addresses for sgen in something else than
SI and DI. It avoids a complex save/restore sequence that
amounts to allocate a register before descending in subtrees.

Fixes #4207.

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6817080

src/cmd/5g/cgen.c

@@ -893,6 +893,21 @@ agenr(Node *n, Node *a, Node *res)
 	nr = n->right;
 
 	switch(n->op) {
+	case ODOT:
+	case ODOTPTR:
+	case OCALLFUNC:
+	case OCALLMETH:
+	case OCALLINTER:
+		igen(n, &n1, res);
+		regalloc(a, types[tptr], &n1);
+		agen(&n1, a);
+		regfree(&n1);
+		break;
+
+	case OIND:
+		cgenr(n->left, a, res);
+		break;
+
 	case OINDEX:
 		p2 = nil;  // to be patched to panicindex.
 		w = n->type->width;

src/cmd/5g/gsubr.c

@@ -361,6 +361,7 @@ regalloc(Node *n, Type *t, Node *o)
 				regpc[i] = (uintptr)getcallerpc(&n);
 				goto out;
 			}
+		print("registers allocated at\n");
 		for(i=REGALLOC_R0; i<=REGALLOC_RMAX; i++)
 			print("%d %p\n", i, regpc[i]);
 		yyerror("out of fixed registers");

src/cmd/6g/cgen.c

@@ -576,6 +576,21 @@ agenr(Node *n, Node *a, Node *res)
 	nr = n->right;
 
 	switch(n->op) {
+	case ODOT:
+	case ODOTPTR:
+	case OCALLFUNC:
+	case OCALLMETH:
+	case OCALLINTER:
+		igen(n, &n1, res);
+		regalloc(a, types[tptr], &n1);
+		agen(&n1, a);
+		regfree(&n1);
+		break;
+
+	case OIND:
+		cgenr(n->left, a, res);
+		break;
+
 	case OINDEX:
 		freelen = 0;
 		w = n->type->width;
@@ -1309,7 +1324,7 @@ stkof(Node *n)
 void
 sgen(Node *n, Node *ns, int64 w)
 {
-	Node nodl, nodr, oldl, oldr, cx, oldcx, tmp;
+	Node nodl, nodr, nodsi, noddi, cx, oldcx, tmp;
 	int32 c, q, odst, osrc;
 
 	if(debug['g']) {
@@ -1353,22 +1368,18 @@ sgen(Node *n, Node *ns, int64 w)
 	}
 
 	if(n->ullman >= ns->ullman) {
-		savex(D_SI, &nodr, &oldr, N, types[tptr]);
-		agen(n, &nodr);
-
-		regalloc(&nodr, types[tptr], &nodr);	// mark nodr as live
-		savex(D_DI, &nodl, &oldl, N, types[tptr]);
-		agen(ns, &nodl);
-		regfree(&nodr);
+		agenr(n, &nodr, N);
+		agenr(ns, &nodl, N);
 	} else {
-		savex(D_DI, &nodl, &oldl, N, types[tptr]);
-		agen(ns, &nodl);
-
-		regalloc(&nodl, types[tptr], &nodl);	// mark nodl as live
-		savex(D_SI, &nodr, &oldr, N, types[tptr]);
-		agen(n, &nodr);
-		regfree(&nodl);
+		agenr(ns, &nodl, N);
+		agenr(n, &nodr, N);
 	}
+	nodreg(&noddi, types[tptr], D_DI);
+	nodreg(&nodsi, types[tptr], D_SI);
+	gmove(&nodl, &noddi);
+	gmove(&nodr, &nodsi);
+	regfree(&nodl);
+	regfree(&nodr);
 
 	c = w % 8;	// bytes
 	q = w / 8;	// quads
@@ -1425,9 +1436,6 @@ sgen(Node *n, Node *ns, int64 w)
 		}
 	}
 
-
-	restx(&nodl, &oldl);
-	restx(&nodr, &oldr);
 	restx(&cx, &oldcx);
 }
 

test/torture.go

@@ -279,12 +279,12 @@ func ChainAssertArrayIndex(u *UArr) J {
 		Children[0].(*UArr).
 		Children[0].(*UArr).
 		Children[0].(*UArr).
-		// Children[0].(*UArr).
-		// Children[0].(*UArr).
-		// Children[0].(*UArr).
-		// Children[0].(*UArr).
-		// Children[0].(*UArr).
-		// Children[0].(*UArr).
+		Children[0].(*UArr).
+		Children[0].(*UArr).
+		Children[0].(*UArr).
+		Children[0].(*UArr).
+		Children[0].(*UArr).
+		Children[0].(*UArr).
 		Children[0]
 }
 
@@ -295,21 +295,20 @@ type UArrPtr struct {
 func (u *UArrPtr) Child(n int) J { return u.Children[n] }
 
 func ChainAssertArrayptrIndex(u *UArrPtr) J {
-	// TODO: don't crash on longer chains.
 	return u.
 		Children[0].(*UArrPtr).
 		Children[0].(*UArrPtr).
 		Children[0].(*UArrPtr).
 		Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
-		// Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
+		Children[0].(*UArrPtr).
 		Children[0]
 }