convert divisions to right-shifts

1 files changed, 6 insertions, 0 deletions

diff --git a/ir.c b/ir.c
index c0de33c..e52e0b9 100644
--- a/ir.c
+++ b/ir.c
@@ -568,6 +568,12 @@ Node *node_idealize(Node *n, Proc *p, Lexer *l) {
 		if (node_eql_i64(CDR(n), 0)) {
 		       lex_error_at(l, CDR(n)->src_pos, LE_ERROR, S("divisor always evaluates to zero"));
 		}
+		{
+			int po2;
+			if (T(CDR(n), N_LIT) && CDR(n)->val.type.t == T_INT && (po2 = u64_power_of_2(CDR(n)->val.u))) {;
+				return NODE(N_OP_SHR, CAR(n), node_new_lit_i64(p, po2));
+			}
+		}
 		break;
 	case N_OP_OR:
 		if (same) return CAR(n);