From 2c0eba5af00a2544e7e15bd8052a53bdb2b6f22f Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 22 Apr 2009 23:57:52 +0200
Subject: [PATCH] re PR c/39855 (Shift optimization discards operands' side
effects)
PR c/39855
* fold-const.c (fold_binary) <case LSHIFT_EXPR>: When optimizing
into 0, use omit_one_operand.
* gcc.dg/torture/pr39855.c: New test.
From-SVN: r146617
---
gcc/ChangeLog | 4 ++++
gcc/fold-const.c | 3 ++-
gcc/testsuite/ChangeLog | 5 +++++
gcc/testsuite/gcc.dg/torture/pr39855.c | 24 ++++++++++++++++++++++++
4 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr39855.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 90730541fe39..7bc4f330f6af 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -3,6 +3,10 @@
* alias.c (find_base_term): Move around LO_SUM case, so that
CONST falls through into PLUS/MINUS handling.
+ PR c/39855
+ * fold-const.c (fold_binary) <case LSHIFT_EXPR>: When optimizing
+ into 0, use omit_one_operand.
+
2009-04-23 Ben Elliston <bje@au.ibm.com>
* config/rs6000/linux-unwind.h (get_regs): Remove type
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index ca07cf167204..f0ff5b69fc18 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -11880,7 +11880,8 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
if (code == LROTATE_EXPR || code == RROTATE_EXPR)
low = low % TYPE_PRECISION (type);
else if (TYPE_UNSIGNED (type) || code == LSHIFT_EXPR)
- return build_int_cst (type, 0);
+ return omit_one_operand (type, build_int_cst (type, 0),
+ TREE_OPERAND (arg0, 0));
else
low = TYPE_PRECISION (type) - 1;
}
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e5c70106164f..7af7fccfe020 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2009-04-22 Jakub Jelinek <jakub@redhat.com>
+
+ PR c/39855
+ * gcc.dg/torture/pr39855.c: New test.
+
2009-04-22 Dodji Seketeli <dodji@redhat.com>
PR c++/39639
diff --git a/gcc/testsuite/gcc.dg/torture/pr39855.c b/gcc/testsuite/gcc.dg/torture/pr39855.c
new file mode 100644
index 000000000000..6d75c38a907a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr39855.c
@@ -0,0 +1,24 @@
+/* PR c/39855 */
+/* { dg-do run { target { int32plus } } } */
+
+extern void abort (void);
+
+int i, j, k;
+
+int
+foo (void)
+{
+ return ++i;
+}
+
+int
+main ()
+{
+ if (__CHAR_BIT__ != 8 || sizeof (int) != 4)
+ return 0;
+ j = foo () << 30 << 2;
+ k = (unsigned) foo () >> 16 >> 16;
+ if (i != 2 || j != 0 || k != 0)
+ abort ();
+ return 0;
+}
--
GitLab