start a new simplification pass

1 files changed, 46 insertions, 0 deletions

diff --git a/simpl.c b/simpl.c
new file mode 100644
index 0000000..384a8da
--- /dev/null
+++ b/simpl.c
@@ -0,0 +1,46 @@
+#include "all.h"
+
+static void
+elimext(Ins *i, int ext, Fn *fn)
+{
+	Tmp *t;
+	Use *u;
+
+	assert(rtype(i->to) == RTmp);
+	t = &fn->tmp[i->to.val];
+	for (u=t->use; u<&t->use[t->nuse]; u++)
+		if (u->type == UIns
+		&& u->u.ins->op == ext
+		&& (u->u.ins->cls == i->cls || i->cls == Kl)) {
+			u->u.ins->op = Ocopy;
+			elimext(u->u.ins, ext, fn);
+		}
+}
+
+/* requires & preserves uses */
+void
+simpl(Fn *fn)
+{
+	Blk *b;
+	Ins *i;
+	int ext;
+
+	for (b=fn->start; b; b=b->link)
+		for (i=b->ins; i<&b->ins[b->nins]; i++)
+			switch (i->op) {
+			case Oloadsb:
+			case Oloadub:
+			case Oloadsh:
+			case Oloaduh:
+				ext = Oextsb + (i->op - Oloadsb);
+				goto Elimext;
+			case Oextsb:
+			case Oextub:
+			case Oextsh:
+			case Oextuh:
+				ext = i->op;
+			Elimext:
+				elimext(i, ext, fn);
+				break;
+			}
+}