[PATCH 22/22] sub: simplify x + (y - x) --> y

[Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>]

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 simplify.c                                | 4 ++++
 validation/optim/simplify-same-addl-sub.c | 1 -
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/simplify.c b/simplify.c
index 65fca35099a6..6caf6cbcf918 100644
--- a/simplify.c
+++ b/simplify.c
@@ -1380,6 +1380,10 @@ static int simplify_add(struct instruction *insn)
 	case OP_NEG:				// (x + -y) --> (x - y)
 		insn->opcode = OP_SUB;
 		return replace_pseudo(insn, &insn->src2, def->src);
+	case OP_SUB:
+		if (src1 == def->src2)		// x + (y - x) --> y
+			return replace_with_pseudo(insn, def->src1);
+		break;
 	}
 
 	return 0;
diff --git a/validation/optim/simplify-same-addl-sub.c b/validation/optim/simplify-same-addl-sub.c
index 51d2b07966f4..9cca1d12ff92 100644
--- a/validation/optim/simplify-same-addl-sub.c
+++ b/validation/optim/simplify-same-addl-sub.c
@@ -3,7 +3,6 @@ int foo(int x, int y) { return x + (y - x); }
 /*
  * check-name: simplify-same-addl-sub
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-contains: ret\\..*%arg2
-- 
2.28.0