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/* Beginning of modification history */
/* Written 02-04-10 by Paul Green (Paul.Green@stratus.com) */
/* End of modification history */
/* This test case is extracted from Perl version 5.7.3. It is
in the Perl_unpack_str function of the pp_pack.c source file.
GCC 2.95.2 improperly assumes that it can compensate for an
extra fsub by performing a fadd. This would work in
fixed-point arithmetic, but does not work in floating-point
arithmetic.
This problem has been seen on HP-UX and on Stratus VOS, both
of which have an HP PA-RISC target (hppa1.1). The Stratus
bug number is gnu_g++-220. */
/* #define _POSIX_C_SOURCE 199506L -- added by Configure */
#include <stdio.h>
#include <string.h>
#include <math.h>
void test(double *result)
{
float afloat;
double adouble;
int checksum = 0;
unsigned cuv = 0;
double cdouble = 0.0;
const int bits_in_uv = 8 * sizeof(cuv);
checksum = 53;
cdouble = -1.0;
if (checksum) {
if (checksum > bits_in_uv) {
double trouble;
adouble = (double) (1 << (checksum & 15));
while (checksum >= 16) {
checksum -= 16;
adouble *= 65536.0;
}
/* At -O1, GCC 2.95.2 compiles the following loop
into:
L$0014
fcmp,dbl,>= %fr4,%fr0
ftest
b L$0014
fadd,dbl %fr4,%fr12,%fr4
fsub,dbl %fr4,%fr12,%fr4
This code depends on the floating-add and
floating-subtract retaining all of the
precision present in the operands. There is
no such guarantee when using floating-point,
as this test case demonstrates.
The code is okay at -O0. */
while (cdouble < 0.0)
cdouble += adouble;
cdouble = modf (cdouble / adouble, &trouble) * adouble;
}
}
*result = cdouble;
}
int main (int argc, char ** argv)
{
double value;
test (&value);
if (argc == 2 && !strcmp(argv[1],"-v"))
printf ("value = %.18e\n", value);
if (value != 9.007199254740991e+15) {
printf ("t001 fails!\n");
return -1;
}
else {
printf ("t001 works.\n");
return 0;
}
}
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