From: Marc Glisse <marc.glisse@inria.fr>
Date: Tue, 17 May 2016 17:57:27 +0000 (+0200)
Subject: x & C -> x if we know that x & ~C == 0
X-Git-Tag: basepoints/gcc-8~6879
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c7986356a1ca8e8e671af74e9e7b76d14238bd5f;p=thirdparty%2Fgcc.git

x & C -> x if we know that x & ~C == 0

2016-05-17  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* match.pd (X & C): New transformation.

gcc/testsuite/
	* gcc.dg/tree-ssa/and-1.c: New testcase.

From-SVN: r236338
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9ec5a9e688af..7f722277fd5d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2016-05-17  Marc Glisse  <marc.glisse@inria.fr>
+
+	* match.pd (X & C): New transformation.
+
 2016-05-17  Marc Glisse  <marc.glisse@inria.fr>
 
 	* match.pd (~X & Y): New transformation.
diff --git a/gcc/match.pd b/gcc/match.pd
index acc41be5a8d9..db8e39cb15d0 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -563,6 +563,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (bitop @0 @0)
   (non_lvalue @0)))
 
+/* x & C -> x if we know that x & ~C == 0.  */
+#if GIMPLE
+(simplify
+ (bit_and SSA_NAME@0 INTEGER_CST@1)
+ (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
+      && (get_nonzero_bits (@0) & wi::bit_not (@1)) == 0)
+  @0))
+#endif
+
 /* x + (x & 1) -> (x + 1) & ~1 */
 (simplify
  (plus:c @0 (bit_and:s @0 integer_onep@1))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 61b6a2290c0d..0e648e58ef09 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2016-05-17  Marc Glisse  <marc.glisse@inria.fr>
+
+	* gcc.dg/tree-ssa/and-1.c: New testcase.
+
 2016-05-17  Marc Glisse  <marc.glisse@inria.fr>
 
 	* gcc.dg/tree-ssa/pr69270.c: Adjust.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/and-1.c b/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
new file mode 100644
index 000000000000..276c2b9bd8ab
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized-raw" } */
+
+int f(int in) {
+  in = in | 3;
+  in = in ^ 1;
+  in = (in & ~(unsigned long)1);
+  return in;
+}
+
+/* { dg-final { scan-tree-dump-not "bit_and_expr" "optimized" } } */