On Mon, Feb 25, 2019 at 10:07:10AM +0100, Eric Botcazou wrote:
> 2019-02-25 Eric Botcazou <ebotca...@adacore.com>
>
> * tree-ssa-dom.c (edge_info::derive_equivalences) <BIT_IOR_EXPR>: Fix
> and move around comment.
> <BIT_AND_EXPR>: Likewise.
> <BIT_NOT_EXPR>: Add specific handling for boolean types.
This broke the following testcase, as mentioned in the PR we have
expected value of the BIT_NOT_EXPR -2 and because that is not zero, the
code assumed that it must be zero, when it actually must be ~-2, i.e. 1.
I know Eric has committed a tweak here, but I view this magic handling as
something meant for boolean types only (if it is correct at all and the
right fix wouldn't be avoid the BIT_NOT_EXPR for the prec > 1 booleans, I
believe the expansion of BIT_NOT_EXPR doesn't have any special case for
BOOLEAN_TYPE). This patch just restores previous behavior for non-boolean
types (basically inlines the first two cases from ssa_name_has_boolean_range
while leaving the problematic third one out, normal integral types with just
known value range of [0,1]).
2019-02-28 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/89536
* tree-ssa-dom.c (edge_info::derive_equivalences) <case BIT_NOT_EXPR>:
Don't use ssa_name_has_boolean_range here, check only for boolean type
or unsigned integral type with precision 1.
* gcc.c-torture/execute/pr89536.c: New test.
--- gcc/tree-ssa-dom.c.jj 2019-02-26 14:13:08.296824100 +0100
+++ gcc/tree-ssa-dom.c 2019-02-28 15:52:08.737369799 +0100
@@ -346,7 +346,14 @@ edge_info::derive_equivalences (tree nam
boolean types with precision > 1. */
if (code == BIT_NOT_EXPR
&& TREE_CODE (rhs) == SSA_NAME
- && ssa_name_has_boolean_range (rhs))
+ /* Don't call ssa_name_has_boolean_range here, that returns
+ true for the following condition, but also when VRP
+ determines [0, 1] range on anything else. BIT_NOT_EXPR
+ of such numbers is [-2, -1] or [-2U, -1U] though. */
+ && (TREE_CODE (TREE_TYPE (rhs)) == BOOLEAN_TYPE
+ || (INTEGRAL_TYPE_P (TREE_TYPE (rhs))
+ && TYPE_UNSIGNED (TREE_TYPE (rhs))
+ && TYPE_PRECISION (TREE_TYPE (rhs)) == 1)))
{
if (integer_zerop (value))
res = build_one_cst (TREE_TYPE (rhs));
--- gcc/testsuite/gcc.c-torture/execute/pr89536.c.jj 2019-02-28
15:53:37.792924793 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr89536.c 2019-02-28
15:53:08.357402412 +0100
@@ -0,0 +1,14 @@
+/* PR tree-optimization/89536 */
+
+int a = 1;
+
+int
+main ()
+{
+ a = ~(a && 1);
+ if (a < -1)
+ a = ~a;
+ if (!a)
+ __builtin_abort ();
+ return 0;
+}
Jakub
