From 5929f3dd0e3a16a1c499bfdde768fe4cf7a38621 Mon Sep 17 00:00:00 2001
From: ceriel <none@none>
Date: Tue, 30 Jan 1990 13:41:36 +0000
Subject: [PATCH] Fix: illegal optimizations of muls

---
 mach/m68020/top/table | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/mach/m68020/top/table b/mach/m68020/top/table
index 3b3b9d22e..d806885a8 100644
--- a/mach/m68020/top/table
+++ b/mach/m68020/top/table
@@ -145,6 +145,9 @@ move.l A, B : bra LAB : labdef L1 : move.l A, B : labdef LAB
 						labdef LAB ;
 /* some strength reduction */
 mulu.l #NUM,DREG			->	muls.l #NUM,DREG ;
+muls.l #NUM,DREG
+	{isshift_once(NUM,X,Y)}		->	asl.l #X,DREG :
+						asl.l #Y,DREG ;
 muls.l #NUM,DREG
 	{is_shift_twice(NUM,X,Y)}	->	asl.l #X,DREG :
 						move.l DREG,-(sp) :
@@ -179,6 +182,38 @@ int no_side_effects(s)
 	/* NOTREACHED */
 }
 
+int isshift_once(s, c1, c2)
+	char *s, *c1, *c2;
+{
+	long atol();
+	register int i = 0;
+	long val = atol(s), pow = 1;
+
+	while (i <= 8) {
+		if (pow & val) {
+			val -= pow;
+			sprintf(c1, "%d", i);
+			strcpy(c2, "0");
+			if (val == 0) return 1;
+			return 0;
+		}
+		pow <<= 1;
+		i++;
+	}
+	i = 0;
+	strcpy(c1, "8");
+	while (i <= 8) {
+		if (pow & val) {
+			val -= pow;
+			sprintf(c2, "%d", i);
+			if (val == 0) return 1;
+			return 0;
+		}
+		pow <<= 1;
+		i++;
+	}
+	return 0;
+}
 
 int is_shift_twice(s, c1, c2)
 	char *s, *c1, *c2;
@@ -196,6 +231,7 @@ int is_shift_twice(s, c1, c2)
 		pow <<= 1;
 		i++;
 	}
+	if (i > 8) return 0;
 	if (pow > 0 && val) {
 		i = 0;
 		while (i <= 8) {
-- 
2.34.1