code review 64170043: cmd/gc: correct liveness for fat variables

src/cmd/5g/cgen.c

Index: src/cmd/5g/cgen.c
===================================================================
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -604,6 +604,7 @@
 		// The generated code is just going to panic, so it need not
 		// be terribly efficient. See issue 3670.
 		tempname(&n1, n->type);
+		gvardef(&n1);
 		clearfat(&n1);
 		regalloc(&n2, types[tptr], res);
 		gins(AMOVW, &n1, &n2);
@@ -1440,10 +1441,6 @@
 		return;
 	}
 
-	// Record site of definition of ns for liveness analysis.
-	if(res->op == ONAME && res->class != PEXTERN)
-		gvardef(res);
-	
 	// If copying .args, that's all the results, so record definition sites
 	// for them for the liveness analysis.
 	if(res->op == ONAME && strcmp(res->sym->name, ".args") == 0)
@@ -1502,8 +1499,12 @@
 		agenr(n, &dst, res);	// temporarily use dst
 		regalloc(&src, types[tptr], N);
 		gins(AMOVW, &dst, &src);
+		if(res->op == ONAME)
+			gvardef(res);
 		agen(res, &dst);
 	} else {
+		if(res->op == ONAME)
+			gvardef(res);
 		agenr(res, &dst, res);
 		agenr(n, &src, N);
 	}
@@ -1638,6 +1639,8 @@
 
 	switch(nl->type->etype) {
 	case TARRAY:
+		if(nl->op == ONAME)
+			gvardef(nl);
 		nodl.xoffset += Array_array;
 		nodl.type = ptrto(nl->type->type);
 
@@ -1668,6 +1671,8 @@
 		goto yes;
 
 	case TSTRING:
+		if(nl->op == ONAME)
+			gvardef(nl);
 		nodl.xoffset += Array_array;
 		nodl.type = ptrto(types[TUINT8]);
 
@@ -1689,6 +1694,8 @@
 		goto yes;
 
 	case TINTER:
+		if(nl->op == ONAME)
+			gvardef(nl);
 		nodl.xoffset += Array_array;
 		nodl.type = ptrto(types[TUINT8]);