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re PR tree-optimization/45034 ("safe" conversion from unsigned to signed char gives broken code)

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2010-07-29  Richard Guenther  <rguenther@suse.de>

	PR middle-end/45034
	* convert.c (convert_to_integer): Always use an unsigned
	type for narrowed negate and bitwise not.

	* gcc.c-torture/execute/pr45034.c: New testcase.

From-SVN: r162673
This commit is contained in:
Richard Guenther 2010-07-29 10:59:54 +00:00 • committed by Richard Biener
parent 6cfcf3eda6
commit 6befd6b053
4 changed files with 57 additions and 8 deletions
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6
gcc/ChangeLog
View file

@ -1,3 +1,9 @@
2010-07-29 Richard Guenther <rguenther@suse.de>
PR middle-end/45034
* convert.c (convert_to_integer): Always use an unsigned
type for narrowed negate and bitwise not.
2010-07-29 Ira Rosen <irar@il.ibm.com>
* tree-vect-loop.c (vect_create_epilog_for_reduction): Switch

9
gcc/convert.c
View file

@ -799,14 +799,7 @@ convert_to_integer (tree type, tree expr)
/* This is not correct for ABS_EXPR,
since we must test the sign before truncation. */
{
tree typex;
/* Don't do unsigned arithmetic where signed was wanted,
or vice versa. */
if (TYPE_UNSIGNED (TREE_TYPE (expr)))
typex = unsigned_type_for (type);
else
typex = signed_type_for (type);
tree typex = unsigned_type_for (type);
return convert (type,
fold_build1 (ex_form, typex,
convert (typex,

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2010-07-29 Richard Guenther <rguenther@suse.de>
PR middle-end/45034
* gcc.c-torture/execute/pr45034.c: New testcase.
2010-07-28 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/45096

45
gcc/testsuite/gcc.c-torture/execute/pr45034.c Normal file
View file

@ -0,0 +1,45 @@
extern void abort (void);
static void fixnum_neg(signed char x, signed char *py, int *pv)
{
unsigned char ux, uy;
ux = (unsigned char)x;
uy = -ux;
*py = (uy <= 127) ? (signed char)uy : (-(signed char)(255 - uy) - 1);
*pv = (x == -128) ? 1 : 0;
}
void __attribute__((noinline)) foo(int x, int y, int v)
{
if (y < -128 || y > 127)
abort();
}
int test_neg(void)
{
signed char x, y;
int v, err;
err = 0;
x = -128;
for (;;) {
fixnum_neg(x, &y, &v);
foo((int)x, (int)y, v);
if ((v && x != -128) || (!v && x == -128))
++err;
if (x == 127)
break;
++x;
}
return err;
}
int main(void)
{
if (sizeof (char) != 1)
return 0;
if (test_neg() != 0)
abort();
return 0;
}