re PR tree-optimization/93156 (abused nonnull attribute evokes new segfault in gcc...

	PR tree-optimization/93156
	* tree-ssa-ccp.c (bit_value_binop): For x * x note that the second
	least significant bit is always clear.

	* gcc.dg/tree-ssa/pr93156.c: New test.

From-SVN: r279951

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f90dc081d0406c7009ec55977909cb13ee47c114..0ead18a53b768da4f6c5dd8d738da510ea4f10e9 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,8 @@
-2019-01-07  Jakub Jelinek  <jakub@redhat.com>
+2020-01-07  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93156
+       * tree-ssa-ccp.c (bit_value_binop): For x * x note that the second
+       least significant bit is always clear.
 
        PR tree-optimization/93118
        * match.pd ((x >> c) << c -> x & (-1<<c)): Add nop_convert?.  Add new

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 403bc8a05f510a97417e3e05139cd5565ae764c5..b5c4bc02834df926ac9bf6f9ea6412dd42685095 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,4 +1,7 @@
-2019-01-07  Jakub Jelinek  <jakub@redhat.com>
+2020-01-07  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93156
+       * gcc.dg/tree-ssa/pr93156.c: New test.
 
        PR tree-optimization/93118
        * gcc.dg/tree-ssa/pr93118.c: New test.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr93156.c b/gcc/testsuite/gcc.dg/tree-ssa/pr93156.c
new file mode 100644 (file)
index 0000000..b8c2af3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr93156.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/93156 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "return 0;" 3 "optimized" } } */
+
+int
+foo (int x)
+{
+  return (x * x) & 2;
+}
+
+unsigned long long
+bar (unsigned long long x)
+{
+  return (x * x) & 2;
+}
+
+int
+baz (int x)
+{
+  x &= -2;
+  return (x * x) & 3;
+}

diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index add3d3fd086775ccbbfd6c02b36d56a6711bab33..be6647db894d2673bc819fc106e6198e13316be8 100644 (file)
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1650,6 +1650,17 @@ bit_value_binop (enum tree_code code, tree type, tree rhs1, tree rhs2)
                   TYPE_SIGN (TREE_TYPE (rhs2)), TYPE_PRECISION (TREE_TYPE (rhs2)),
                   value_to_wide_int (r2val), r2val.mask);
 
+  /* (x * x) & 2 == 0.  */
+  if (code == MULT_EXPR && rhs1 == rhs2 && TYPE_PRECISION (type) > 1)
+    {
+      widest_int m = 2;
+      if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
+       value = wi::bit_and_not (value, m);
+      else
+       value = 0;
+      mask = wi::bit_and_not (mask, m);
+    }
+
   if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
     {
       val.lattice_val = CONSTANT;