[PATCH v3 12/15] simplify OP((x | C), K) when (C & M) == 0

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

In an expression like OP((x | C), K), if the inner constant
(C) and the effective mask (M) corresponding to OP(_, K) are
disjoint ((C & M) == 0), then the OR with the constant is
unneeded and can be optimized away since the constant will be
'cleared' by the mask, giving: OP(x, K)

For example, code like:
	int foo(int x)
	{
		return (x | 0xfffff000) & 0xfff;
	}

is now optimized into:
	foo:
		and.32      %r3 <- %arg1, $0xfff
		ret.32      %r3

while previously the OR mask was not optimized away:
	foo:
		or.32       %r2 <- %arg1, $0xfffff000
		and.32      %r3 <- %r2, $0xfff
		ret.32      %r3

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 simplify.c                          | 9 +++++++++
 validation/optim/and-or-bf0.c       | 1 -
 validation/optim/and-or-constant0.c | 1 -
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/simplify.c b/simplify.c
index a347af41c..6c4546fcb 100644
--- a/simplify.c
+++ b/simplify.c
@@ -613,6 +613,15 @@ static int simplify_mask_or(struct instruction *insn, unsigned long long mask, s
 	if (src2->type == PSEUDO_REG) {
 		if ((rc = simplify_mask_or_and(insn, mask, src2, src1)))
 			return rc;
+	} else if (src2->type == PSEUDO_VAL) {
+		unsigned long long oval = src2->value;
+		unsigned long long nval = oval & mask;
+		// Try to simplify:
+		//	OP(OR(x, C), K)
+		if (nval == 0) {
+			// if (C & M) == 0: OR(x, C) -> x
+			return replace_pseudo(insn, &insn->src1, src1);
+		}
 	}
 	return 0;
 }
diff --git a/validation/optim/and-or-bf0.c b/validation/optim/and-or-bf0.c
index a17ff82d3..cfaff4f20 100644
--- a/validation/optim/and-or-bf0.c
+++ b/validation/optim/and-or-bf0.c
@@ -17,7 +17,6 @@ void bar(struct s *p, int a)
 /*
  * check-name: and-or-bf0
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-pattern(3): and\\.
diff --git a/validation/optim/and-or-constant0.c b/validation/optim/and-or-constant0.c
index e3ff0fa46..dcf440f33 100644
--- a/validation/optim/and-or-constant0.c
+++ b/validation/optim/and-or-constant0.c
@@ -6,7 +6,6 @@ int foo(int x)
 /*
  * check-name: and-or-constant0
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-excludes: or\\.
-- 
2.18.0