util/romcc: avoid shifting more than the variable's width

That's undefined behavior in C

Change-Id: I671ed8abf02e57a7cc993d1a85354e905f51717d
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Found-by: Coverity Scan #1229557
Reviewed-on: https://review.coreboot.org/18014
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/util/romcc/romcc.c b/util/romcc/romcc.c
index b08f8e8..aa41ccf 100644
--- a/util/romcc/romcc.c
+++ b/util/romcc/romcc.c
@@ -10021,13 +10021,13 @@
 			/* Ensure I am properly sign extended */
 			if (size_of(state, right->type) < size_of(state, ins->type) &&
 				is_signed(right->type)) {
-				long_t val;
+				uint64_t val;
 				int shift;
 				shift = SIZEOF_LONG - size_of(state, right->type);
 				val = left;
 				val <<= shift;
 				val >>= shift;
-				left = val;
+				left = (ulong_t)val;
 			}
 			mkconst(state, ins, left);
 			break;