From 10c21653c1648fb7619ebe8f9787365d78574a11 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Fri, 26 Nov 2004 23:25:30 -0700
Subject: [PATCH] Simplify constant subtraction into addition.

We're much better at simplifying addition, so let's try to fix it
up.
---
 simplify.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/simplify.c b/simplify.c
index 3d7cd72e..85c04c1d 100644
--- a/simplify.c
+++ b/simplify.c
@@ -233,7 +233,14 @@ static int simplify_constant_rightside(struct instruction *insn)
 	long long value = insn->src2->value;
 
 	switch (insn->opcode) {
-	case OP_ADD: case OP_SUB:
+	case OP_SUB:
+		if (value) {
+			insn->opcode = OP_ADD;
+			insn->src2 = value_pseudo(-value);
+			return REPEAT_CSE;
+		}
+	/* Fallthrough */
+	case OP_ADD:
 	case OP_OR: case OP_XOR:
 	case OP_SHL: case OP_SHR:
 		if (!value)
-- 
2.11.4.GIT