This adds some extra checks to see if we can remove the casts
for signed integer overflow reasons while doing a negative.
This is needed more due to the recent patch which adds them
in some cases.
This also changes TYPE_UNSIGNED to be TYPE_OVERFLOW_WRAPS to
allow this to happen with -fwrapv too.
Changes since v1:
* Use expr_not_equal_to and simplify the if stmt.
Also use TYPE_OVERFLOW_WRAPS instead of TYPE_UNSIGNED.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/107765
gcc/ChangeLog:
* match.pd (`(cast)-(cast)a`): Expand to
use expr_not_equal_to of INT_MIN.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/neg-cast-1.c: New test.
* gcc.dg/tree-ssa/neg-cast-4.c: New test.
Signed-off-by: Andrea Pinski <[email protected]>
---
gcc/match.pd | 10 +++++++---
gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c | 23 ++++++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c | 16 +++++++++++++++
3 files changed, 46 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 4631e811108..30657fa5bae 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1231,13 +1231,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
show up. Else it is safe if the negation is done in an unsigned type.
Note the outer cast cannot be a boolean type as the only valid values
are 0,-1/1 (depending on the signedness of the boolean) and the negative
- is there to get the correct value. */
+ is there to get the correct value.
+ Also handle the case where we know that we won't cause a signed
+ integer overflow at the point of the negation. */
(simplify
- (convert (negate:s@1 (convert:s @0)))
+ (convert (negate:s@1 (convert:s@ic @0)))
(if (INTEGRAL_TYPE_P (type)
&& tree_nop_conversion_p (type, TREE_TYPE (@1))
&& (TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0))
- || TYPE_UNSIGNED (type))
+ || TYPE_OVERFLOW_WRAPS (type)
+ || expr_not_equal_to (@ic, wi::min_value (signed_type_for (type)),
+ gimple_match_ctx (@1)))
&& TREE_CODE (type) != BOOLEAN_TYPE)
(negate (convert @0))))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c
new file mode 100644
index 00000000000..ec5d0e15251
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-1.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized -fdump-tree-cddce1" } */
+/* PR tree-optimization/107765 */
+
+int a(int input)
+{
+ if (input == -__INT_MAX__-1) return 1;
+ unsigned t = input;
+ int tt = -t;
+ return tt == -input;
+}
+
+int b(int input)
+{
+ if (input == -__INT_MAX__-1) __builtin_trap();
+ unsigned t = input;
+ int tt = -t;
+ return tt;
+}
+
+/* { dg-final { scan-tree-dump "return 1" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "\\(unsigned int\\)" "cddce1" } } */
+/* { dg-final { scan-tree-dump-not "\\(int\\)" "cddce1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c
b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c
new file mode 100644
index 00000000000..fe3fe6a2ecc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/neg-cast-4.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-phiopt2-details -fdump-tree-optimized" } */
+/* PR tree-optimization/107765 */
+
+int b(int input)
+{
+ if (input == -__INT_MAX__-1) return input;
+ unsigned t = input;
+ int tt = -t;
+ return tt;
+}
+
+/* { dg-final { scan-tree-dump-not "if " "optimized" } } */
+/* { dg-final { scan-tree-dump-times "\\(unsigned int\\)" 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "\\(int\\)" 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "converted to straightline code" 1
"phiopt2" } } */
--
2.43.0
