aboutsummaryrefslogtreecommitdiff
path: root/gcc
diff options
context:
space:
mode:
authorRoger Sayle <roger@eyesopen.com>2006-02-26 16:10:30 +0000
committerRoger Sayle <sayle@gcc.gnu.org>2006-02-26 16:10:30 +0000
commitcef65eaa924c2c9eff16af8a19b051ad61d65ec2 (patch)
tree023ddcdab0e55bd4a22ee47cd852342b1535a05e /gcc
parenta861485caf6698fe171b1d80a78f3f73091615eb (diff)
downloadgcc-cef65eaa924c2c9eff16af8a19b051ad61d65ec2.zip
gcc-cef65eaa924c2c9eff16af8a19b051ad61d65ec2.tar.gz
gcc-cef65eaa924c2c9eff16af8a19b051ad61d65ec2.tar.bz2
fold-const.c (fold_binary): Fold (X & 1) ^ 1 as (X & 1) == 0.
* fold-const.c (fold_binary) <BIT_XOR_EXPR>: Fold (X & 1) ^ 1 as (X & 1) == 0. <BIT_AND_EXPR>: Fold (X ^ 1) & 1 and ~X & 1 as (X & 1) == 0. * gcc.dg/fold-even-1.c: New test case. From-SVN: r111454
Diffstat (limited to 'gcc')
-rw-r--r--gcc/ChangeLog6
-rw-r--r--gcc/fold-const.c29
-rw-r--r--gcc/testsuite/ChangeLog4
-rw-r--r--gcc/testsuite/gcc.dg/fold-even-1.c33
4 files changed, 72 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ead872d..90cff90 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,10 @@
2006-02-26 Roger Sayle <roger@eyesopen.com>
+
+ * fold-const.c (fold_binary) <BIT_XOR_EXPR>: Fold (X & 1) ^ 1 as
+ (X & 1) == 0.
+ <BIT_AND_EXPR>: Fold (X ^ 1) & 1 and ~X & 1 as (X & 1) == 0.
+
+2006-02-26 Roger Sayle <roger@eyesopen.com>
James A. Morrison <phython@gcc.gnu.org>
PR middle-end/21137
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 7eb4d91..e85534a 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8740,6 +8740,13 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
fold_convert (type, TREE_OPERAND (arg0, 0)),
fold_convert (type, TREE_OPERAND (arg1, 0)));
+ /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
+ if (TREE_CODE (arg0) == BIT_AND_EXPR
+ && integer_onep (TREE_OPERAND (arg0, 1))
+ && integer_onep (arg1))
+ return fold_build2 (EQ_EXPR, type, arg0,
+ build_int_cst (TREE_TYPE (arg0), 0));
+
/* See if this can be simplified into a rotate first. If that
is unsuccessful continue in the association code. */
goto bit_rotate;
@@ -8792,6 +8799,28 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
&& reorder_operands_p (arg0, TREE_OPERAND (arg1, 0)))
return omit_one_operand (type, arg0, TREE_OPERAND (arg1, 0));
+ /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
+ if (TREE_CODE (arg0) == BIT_XOR_EXPR
+ && integer_onep (TREE_OPERAND (arg0, 1))
+ && integer_onep (arg1))
+ {
+ tem = TREE_OPERAND (arg0, 0);
+ return fold_build2 (EQ_EXPR, type,
+ fold_build2 (BIT_AND_EXPR, TREE_TYPE (tem), tem,
+ build_int_cst (TREE_TYPE (tem), 1)),
+ build_int_cst (TREE_TYPE (tem), 0));
+ }
+ /* Fold ~X & 1 as (X & 1) == 0. */
+ if (TREE_CODE (arg0) == BIT_NOT_EXPR
+ && integer_onep (arg1))
+ {
+ tem = TREE_OPERAND (arg0, 0);
+ return fold_build2 (EQ_EXPR, type,
+ fold_build2 (BIT_AND_EXPR, TREE_TYPE (tem), tem,
+ build_int_cst (TREE_TYPE (tem), 1)),
+ build_int_cst (TREE_TYPE (tem), 0));
+ }
+
t1 = distribute_bit_expr (code, type, arg0, arg1);
if (t1 != NULL_TREE)
return t1;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index deb3000..a93b73c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
2006-02-26 Roger Sayle <roger@eyesopen.com>
+ * gcc.dg/fold-even-1.c: New test case.
+
+2006-02-26 Roger Sayle <roger@eyesopen.com>
+
PR middle-end/21137
* gcc.dg/fold-eqandshift-1.c: New test case.
diff --git a/gcc/testsuite/gcc.dg/fold-even-1.c b/gcc/testsuite/gcc.dg/fold-even-1.c
new file mode 100644
index 0000000..8e6539c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-even-1.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-original" } */
+int test1(int a)
+{
+ return !(a & 1);
+}
+
+int test2(int b)
+{
+ return (b & 1) == 0;
+}
+
+int test3(int c)
+{
+ return (c & 1) ^ 1;
+}
+
+int test4(int d)
+{
+ return (d ^ 1) & 1;
+}
+
+int test5(int e)
+{
+ return ~e & 1;
+}
+
+/* { dg-final { scan-tree-dump-times "\\(a \& 1\\) == 0" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "\\(b \& 1\\) == 0" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "\\(c \& 1\\) == 0" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "\\(d \& 1\\) == 0" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "\\(e \& 1\\) == 0" 1 "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */