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 9ec5a9e688af5ec4e460bf3874a73674efbe0a80..7f722277fd5d2796bb322dc4c0e68cf5978b7785 100644 (file)
--- 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 acc41be5a8d96e17dd0176b7bdc49977f54621c0..db8e39cb15d0868c2b74a50a750a7ee9260e485e 100644 (file)
--- 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 61b6a2290c0d22d72e9235b1866534a4021f6b3a..0e648e58ef09c941969f84218bac0576e80e0665 100644 (file)
--- 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 (file)
index 0000000..276c2b9
--- /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" } } */