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* [gcc r14-4661] [PR31531] MATCH: Improve ~a < ~b and ~a < CST, allow a nop cast inbetween ~ and a/b
@ 2023-10-16 17:01 Andrew Pinski
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From: Andrew Pinski @ 2023-10-16 17:01 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:29a4453c7b8a86d242dab89b9e4d222749fd911e
commit r14-4661-g29a4453c7b8a86d242dab89b9e4d222749fd911e
Author: Andrew Pinski <pinskia@gmail.com>
Date: Sun Oct 15 15:18:42 2023 -0700
[PR31531] MATCH: Improve ~a < ~b and ~a < CST, allow a nop cast inbetween ~ and a/b
Currently we able to simplify `~a CMP ~b` to `b CMP a` but we should allow a nop
conversion in between the `~` and the `a` which can show up. A similarly thing should
be done for `~a CMP CST`.
I had originally submitted the `~a CMP CST` case as
https://gcc.gnu.org/pipermail/gcc-patches/2021-November/585088.html;
I noticed we should do the same thing for the `~a CMP ~b` case and combined
it with that one here.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
PR tree-optimization/31531
gcc/ChangeLog:
* match.pd (~X op ~Y): Allow for an optional nop convert.
(~X op C): Likewise.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr31531-1.c: New test.
* gcc.dg/tree-ssa/pr31531-2.c: New test.
Diff:
---
gcc/match.pd | 10 +++++----
gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c | 19 +++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c | 34 +++++++++++++++++++++++++++++++
3 files changed, 59 insertions(+), 4 deletions(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index 51e5065d0860..e76ec1ec034a 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5944,18 +5944,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Fold ~X op ~Y as Y op X. */
(for cmp (simple_comparison)
(simplify
- (cmp (bit_not@2 @0) (bit_not@3 @1))
+ (cmp (nop_convert1?@4 (bit_not@2 @0)) (nop_convert2? (bit_not@3 @1)))
(if (single_use (@2) && single_use (@3))
- (cmp @1 @0))))
+ (with { tree otype = TREE_TYPE (@4); }
+ (cmp (convert:otype @1) (convert:otype @0))))))
/* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
(for cmp (simple_comparison)
scmp (swapped_simple_comparison)
(simplify
- (cmp (bit_not@2 @0) CONSTANT_CLASS_P@1)
+ (cmp (nop_convert? (bit_not@2 @0)) CONSTANT_CLASS_P@1)
(if (single_use (@2)
&& (TREE_CODE (@1) == INTEGER_CST || TREE_CODE (@1) == VECTOR_CST))
- (scmp @0 (bit_not @1)))))
+ (with { tree otype = TREE_TYPE (@1); }
+ (scmp (convert:otype @0) (bit_not @1))))))
(for cmp (simple_comparison)
(simplify
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
new file mode 100644
index 000000000000..c27299151ebc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/31531 */
+
+int f(int a)
+{
+ int b = ~a;
+ return b<0;
+}
+
+
+int f1(unsigned a)
+{
+ int b = ~a;
+ return b<0;
+}
+/* We should convert the above two functions from b <0 to ((int)a) >= 0. */
+/* { dg-final { scan-tree-dump-times ">= 0" 2 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
new file mode 100644
index 000000000000..865ea2922150
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/31531 */
+
+int f0(unsigned x, unsigned t)
+{
+ x = ~x;
+ t = ~t;
+ int xx = x;
+ int tt = t;
+ return tt < xx;
+}
+
+int f1(unsigned x, int t)
+{
+ x = ~x;
+ t = ~t;
+ int xx = x;
+ int tt = t;
+ return tt < xx;
+}
+
+int f2(int x, unsigned t)
+{
+ x = ~x;
+ t = ~t;
+ int xx = x;
+ int tt = t;
+ return tt < xx;
+}
+
+
+/* We should be able to remove all ~ from the above functions. */
+/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */
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