From: Matthias Braun <matthias.braun@kit.edu>
Date: Fri, 24 Aug 2012 16:51:21 +0000 (+0200)
Subject: shrink load mode if not all bits are used
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=72d5c30047929742f6b91850bde05e5e3c1ac00b;p=libfirm

shrink load mode if not all bits are used
---

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index d37db02cc..f9958a141 100644
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -5597,6 +5597,26 @@ static ir_node *transform_node_Conv(ir_node *n)
 		}
 	}
 
+	/* shrink mode of load if possible. */
+	if (is_Proj(a)) {
+		ir_node *pred = get_Proj_pred(a);
+		if (is_Load(pred)) {
+			/* only do it if we are the only user (otherwise the risk is too
+			 * great that we end up with 2 loads instead of one). */
+			ir_graph *irg = get_irn_irg(n);
+			if (edges_activated(irg) && get_irn_n_edges(a) == 1) {
+				ir_mode *load_mode = get_Load_mode(pred);
+				if (!mode_is_float(load_mode) && !mode_is_float(mode) &&
+					get_mode_size_bits(mode) <= get_mode_size_bits(load_mode)
+					&& !be_get_backend_param()->byte_order_big_endian) {
+					set_Load_mode(pred, mode);
+					set_irn_mode(a, mode);
+					return a;
+				}
+			}
+		}
+	}
+
 	return n;
 }