[PATCH v2 14/15] simplify OP((x | C), K) when (C & M) != C

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

If the effective mask (C & M) is different than the outer mask C,
then this later can be replaced by the smaller (C & M), giving:
OP((x | M'), K) with M' == (C & M).

For example, code like:
	int foo(int x)
	{
		return (x | 0xfffffff0) & 0xfff;
	}

is now simplified into:
	foo:
		or.32       %r2 <- %arg1, $0xff0
		and.32      %r3 <- %r2, $0xfff
		ret.32      %r3

while previously, the constant was not reduced:
	foo:
		or.32       %r2 <- %arg1, $0xfffffff0
		and.32      %r3 <- %r2, $0xfff
		ret.32      %r3

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 simplify.c                          | 4 ++++
 validation/optim/and-or-constant2.c | 1 -
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/simplify.c b/simplify.c
index 755371002..5a802d207 100644
--- a/simplify.c
+++ b/simplify.c
@@ -622,6 +622,10 @@ static int simplify_mask_or(struct instruction *insn, unsigned long long mask, s
 			// if (C & M) == M: OR(x, C) -> (C & M)
 			return replace_pseudo(insn, &insn->src1, value_pseudo(nval));
 		}
+		if (nval != oval && !multi_users(or->target)) {
+			// if (C & M) != C: OR(x, C) -> OR(x, (C & M))
+			return replace_pseudo(or, &or->src2, value_pseudo(nval));
+		}
 	}
 	return 0;
 }
diff --git a/validation/optim/and-or-constant2.c b/validation/optim/and-or-constant2.c
index 82e0d3c69..d7e66f9c0 100644
--- a/validation/optim/and-or-constant2.c
+++ b/validation/optim/and-or-constant2.c
@@ -6,7 +6,6 @@ int foo(int x)
 /*
  * check-name: and-or-constant2
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-contains: or\\..*\\$0xff0
-- 
2.18.0