From e6620e86376c650754216a2bf4601e76cf15e9c8 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu@codesourcery.com>
Date: Sat, 28 Jan 2006 05:19:44 +0000
Subject: [PATCH] re PR c/19606 (wrong code for arith.expr: (((unsigned
int)(signed int) a ) / 2LL) with signed char a=-4)
gcc/
PR c/19606.
* c-typeck.c (build_binary_op): Perform implicit casts of
operands before shortening them.
gcc/testsuite/
PR c/19606.
* gcc.c-torture/execute/pr19606.c: New.
From-SVN: r110321
---
gcc/ChangeLog | 6 ++++
gcc/c-typeck.c | 31 ++++++++++++++---
gcc/testsuite/ChangeLog | 5 +++
gcc/testsuite/gcc.c-torture/execute/pr19606.c | 34 +++++++++++++++++++
4 files changed, 72 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr19606.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 16762cc9780b..7c1baa3bd637 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2006-01-28 Kazu Hirata <kazu@codesourcery.com>
+
+ PR c/19606.
+ * c-typeck.c (build_binary_op): Perform implicit casts of
+ operands before shortening them.
+
2006-01-27 H.J. Lu <hongjiu.lu@intel.com>
* df-scan.c (df_record_entry_block_defs): Check if
diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index e1f784581463..ef518951c52f 100644
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -8101,12 +8101,35 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
if (shorten && none_complex)
{
int unsigned0, unsigned1;
- tree arg0 = get_narrower (op0, &unsigned0);
- tree arg1 = get_narrower (op1, &unsigned1);
- /* UNS is 1 if the operation to be done is an unsigned one. */
- int uns = TYPE_UNSIGNED (result_type);
+ tree arg0, arg1;
+ int uns;
tree type;
+ /* Cast OP0 and OP1 to RESULT_TYPE. Doing so prevents
+ excessive narrowing when we call get_narrower below. For
+ example, suppose that OP0 is of unsigned int extended
+ from signed char and that RESULT_TYPE is long long int.
+ If we explicitly cast OP0 to RESULT_TYPE, OP0 would look
+ like
+
+ (long long int) (unsigned int) signed_char
+
+ which get_narrower would narrow down to
+
+ (unsigned int) signed char
+
+ If we do not cast OP0 first, get_narrower would return
+ signed_char, which is inconsistent with the case of the
+ explicit cast. */
+ op0 = convert (result_type, op0);
+ op1 = convert (result_type, op1);
+
+ arg0 = get_narrower (op0, &unsigned0);
+ arg1 = get_narrower (op1, &unsigned1);
+
+ /* UNS is 1 if the operation to be done is an unsigned one. */
+ uns = TYPE_UNSIGNED (result_type);
+
final_type = result_type;
/* Handle the case that OP0 (or OP1) does not *contain* a conversion
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 50cc3235b621..2f2f8c67727c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-01-28 Kazu Hirata <kazu@codesourcery.com>
+
+ PR c/19606.
+ * gcc.c-torture/execute/pr19606.c: New.
+
2006-01-27 Carlos O'Donell <carlos@codesourcery.com>
* gcc.dg/pragma-re-4.c: New test.
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr19606.c b/gcc/testsuite/gcc.c-torture/execute/pr19606.c
new file mode 100644
index 000000000000..d1e836fa028a
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr19606.c
@@ -0,0 +1,34 @@
+/* PR c/19606
+ The C front end used to shorten the type of a division to a type
+ that does not preserve the semantics of the original computation.
+ Make sure that won't happen. */
+
+signed char a = -4;
+
+int
+foo (void)
+{
+ return ((unsigned int) (signed int) a) / 2LL;
+}
+
+int
+bar (void)
+{
+ return ((unsigned int) (signed int) a) % 5LL;
+}
+
+int
+main (void)
+{
+ int r;
+
+ r = foo ();
+ if (r != ((unsigned int) (signed int) (signed char) -4) / 2LL)
+ abort ();
+
+ r = bar ();
+ if (r != ((unsigned int) (signed int) (signed char) -4) % 5LL)
+ abort ();
+
+ exit (0);
+}
--
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