From: Andrew MacLeod <amacleod@redhat.com>
To: gcc-patches <gcc-patches@gcc.gnu.org>
Subject: [GCC 11] [COMMITTED] Fix build_gt and build_lt for signed 1 bit values.
Date: Wed, 14 Jul 2021 18:15:22 -0400 [thread overview]
Message-ID: <ef649d2f-b051-409c-b9a9-b4cc58291d62@redhat.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 135 bytes --]
Cherry picked from 84f7bab89279ca1234fef88929c74caeda8cb55e
Bootstrapped on x86_64-pc-linux-gnu with no regressions. pushed.
Andrew
[-- Attachment #2: 0008-Fix-build_gt-and-build_lt-for-signed-1-bit-values.patch --]
[-- Type: text/x-patch, Size: 2813 bytes --]
From b977e6b29c67be81df882d1f5cc7eb6a5d8c98a0 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Wed, 30 Jun 2021 14:15:53 -0400
Subject: [PATCH 8/8] Fix build_gt and build_lt for signed 1 bit values.
Signed 1 bit values have a range of [-1, 0] but neither (0 - 1) nor (-1 + 1)
can be represented. For signed values, add or subtract -1 as appropriate.
PR tree-optimization/101223
gcc/
* range-op.cc (build_lt): Add -1 for signed values.
(built_gt): Subtract -1 for signed values.
gcc/testsuite/
* gcc.dg/pr101223.c: New.
(cherry picked from commit 84f7bab89279ca1234fef88929c74caeda8cb55e)
---
gcc/range-op.cc | 18 ++++++++++++--
gcc/testsuite/gcc.dg/pr101223.c | 44 +++++++++++++++++++++++++++++++++
2 files changed, 60 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr101223.c
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 3a35a2fb25b..c33f4edc2c1 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -562,7 +562,14 @@ static void
build_lt (irange &r, tree type, const wide_int &val)
{
wi::overflow_type ov;
- wide_int lim = wi::sub (val, 1, TYPE_SIGN (type), &ov);
+ wide_int lim;
+ signop sgn = TYPE_SIGN (type);
+
+ // Signed 1 bit cannot represent 1 for subtraction.
+ if (sgn == SIGNED)
+ lim = wi::add (val, -1, sgn, &ov);
+ else
+ lim = wi::sub (val, 1, sgn, &ov);
// If val - 1 underflows, check if X < MIN, which is an empty range.
if (ov)
@@ -585,7 +592,14 @@ static void
build_gt (irange &r, tree type, const wide_int &val)
{
wi::overflow_type ov;
- wide_int lim = wi::add (val, 1, TYPE_SIGN (type), &ov);
+ wide_int lim;
+ signop sgn = TYPE_SIGN (type);
+
+ // Signed 1 bit cannot represent 1 for addition.
+ if (sgn == SIGNED)
+ lim = wi::sub (val, -1, sgn, &ov);
+ else
+ lim = wi::add (val, 1, sgn, &ov);
// If val + 1 overflows, check is for X > MAX, which is an empty range.
if (ov)
r.set_undefined ();
diff --git a/gcc/testsuite/gcc.dg/pr101223.c b/gcc/testsuite/gcc.dg/pr101223.c
new file mode 100644
index 00000000000..6d5a247fa6c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr101223.c
@@ -0,0 +1,44 @@
+/* PR tree-optimization/101223 */
+/* { dg-do run } */
+/* { dg-options "-O2 " } */
+
+struct {
+ int a : 1;
+} b;
+int c = 1, d;
+int foo1() {
+ for (; d < 2; d++) {
+ int e = ~c, f = 0, g;
+ if (e) {
+ f = c;
+ g = b.a;
+ b.a = f;
+ if (b.a >= g)
+ __builtin_abort();
+ }
+ c = f;
+ b.a = g;
+ }
+ return 0;
+}
+
+int foo2() {
+ for (; d < 2; d++) {
+ int e = ~c, f = 0, g;
+ if (e) {
+ f = c;
+ g = b.a;
+ b.a = f;
+ if (g <= b.a)
+ __builtin_abort();
+ }
+ c = f;
+ b.a = g;
+ }
+ return 0;
+}
+int main ()
+{
+ return foo1() + foo2();
+}
+
--
2.17.2
next reply other threads:[~2021-07-14 22:15 UTC|newest]
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2021-07-14 22:15 Andrew MacLeod [this message]
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2021-07-14 22:15 Andrew MacLeod
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