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