http://llvm.org/bugs/show_bug.cgi?id=15054
Bug #: 15054
Summary: 32bit Build always write's snan
Product: clang
Version: 3.2
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: C++
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected], [email protected]
Classification: Unclassified
Have a problem that signaling nan's are always written when built with -m32.
Test case (original here: https://gist.github.com/0c340629e451ff31ef66)
#include <limits>
#include <cstdio>
#include <cstring>
int main()
{
union {
unsigned char b[sizeof(double)];
double d;
float f;
} u;
memset(&u, 0, sizeof(u));
u.f = std::numeric_limits<float>::signaling_NaN(); //__builtin_nansf("");
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n",
u.b[0], u.b[1], u.b[2], u.b[3],
u.b[4], u.b[5], u.b[6], u.b[7]);
u.f = std::numeric_limits<float>::quiet_NaN(); //__builtin_nanf("");
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n",
u.b[0], u.b[1], u.b[2], u.b[3],
u.b[4], u.b[5], u.b[6], u.b[7]);
u.d = std::numeric_limits<double>::signaling_NaN(); //__builtin_nans("");
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n",
u.b[0], u.b[1], u.b[2], u.b[3],
u.b[4], u.b[5], u.b[6], u.b[7]);
u.d = std::numeric_limits<double>::quiet_NaN(); //__builtin_nan("");
printf("%02x %02x %02x %02x %02x %02x %02x %02x\n",
u.b[0], u.b[1], u.b[2], u.b[3],
u.b[4], u.b[5], u.b[6], u.b[7]);
}
$ for CXX in clang++ g++; do for M in 32 64; do $CXX -m$M -o tmp/snan-$CXX$M
tmp/snan.cc; echo "*** $CXX $M bits"; tmp/snan-$CXX$M; done; done
*** clang++ 32 bits
00 00 c0 ff 00 00 00 00
00 00 c0 ff 00 00 00 00
00 00 00 00 00 00 f8 ff
00 00 00 00 00 00 f8 ff
*** clang++ 64 bits
00 00 a0 7f 00 00 00 00
00 00 c0 7f 00 00 00 00
00 00 00 00 00 00 f4 7f
00 00 00 00 00 00 f8 7f
*** g++ 32 bits
00 00 e0 7f 00 00 00 00
00 00 c0 7f 00 00 00 00
00 00 00 00 00 00 fc 7f
00 00 00 00 00 00 f8 7f
*** g++ 64 bits
00 00 a0 7f 00 00 00 00
00 00 c0 7f 00 00 00 00
00 00 00 00 00 00 f4 7f
00 00 00 00 00 00 f8 7f
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