gc, 8g, 8l: fix a handful of warnings

8g/cgen.c
        print format type mismatch

8l/asm.c
        resoff set and not used

gc/pgen.c
        misleading comparison INT > 0x80000000

gc/reflect.c
        dalgsym must be static to match forward declaration

gc/subr.c
        assumed_equal set and not used
        hashmem's second argument is not used

gc/walk.c
        duplicated (unreachable) code

R=rsc
CC=golang-dev
https://golang.org/cl/5651079

src/cmd/8g/cgen.c

@@ -1146,7 +1146,7 @@ sgen(Node *n, Node *res, int64 w)
 	int32 c, q, odst, osrc;
 
 	if(debug['g']) {
-		print("\nsgen w=%ld\n", w);
+		print("\nsgen w=%lld\n", w);
 		dump("r", n);
 		dump("res", res);
 	}

src/cmd/8l/asm.c

@@ -1004,6 +1004,9 @@ asmb(void)
 			phsh(ph, sh);
 		}
 
+		// Additions to the reserved area must be above this line.
+		USED(resoff);
+
 		elfphload(&segtext);
 		elfphload(&segdata);
 

src/cmd/gc/pgen.c

@@ -124,7 +124,7 @@ compile(Node *fn)
 		print("allocauto: %lld to %lld\n", oldstksize, (vlong)stksize);
 
 	setlineno(curfn);
-	if(stksize+maxarg > (1ULL<<31))
+	if((int64)stksize+maxarg > (1ULL<<31))
 		yyerror("stack frame too large (>2GB)");
 
 	defframe(ptxt);

src/cmd/gc/reflect.c

@@ -907,7 +907,7 @@ dumptypestructs(void)
 	}
 }
 
-Sym*
+static Sym*
 dalgsym(Type *t)
 {
 	int ot;

src/cmd/gc/subr.c

@@ -1108,11 +1108,9 @@ eqtype1(Type *t1, Type *t2, TypePairList *assumed_equal)
 	goto no;
 
 yes:
-	assumed_equal = l.next;
 	return 1;
 
 no:
-	assumed_equal = l.next;
 	return 0;
 }
 
@@ -2491,7 +2489,7 @@ genwrapper(Type *rcvr, Type *method, Sym *newnam, int iface)
 }
 
 static Node*
-hashmem(Type *t, vlong width)
+hashmem(Type *t)
 {
 	Node *tfn, *n;
 	Sym *sym;
@@ -2519,7 +2517,7 @@ hashfor(Type *t)
 	a = algtype1(t, nil);
 	switch(a) {
 	case AMEM:
-		return hashmem(t, t->width);
+		return hashmem(t);
 	case AINTER:
 		sym = pkglookup("interhash", runtimepkg);
 		break;
@@ -2667,7 +2665,7 @@ genhash(Sym *sym, Type *t)
 					size = t->width - first->width;  // first->width is offset
 				else
 					size = t1->width - first->width;  // both are offsets
-				hashel = hashmem(first->type, size);
+				hashel = hashmem(first->type);
 				// hashel(h, size, &p.first)
 				call = nod(OCALL, hashel, N);
 				call->list = list(call->list, nh);

src/cmd/gc/walk.c

@@ -1194,10 +1194,6 @@ walkexpr(Node **np, NodeList **init)
 		n = r;
 		goto ret;
 
-	
-		n = r;
-		goto ret;
-
 	case OARRAYLIT:
 	case OMAPLIT:
 	case OSTRUCTLIT: