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instruction: 0.496
runtime: 0.302
syscall: 0.202
qemu-ppc (user) incorrectly converts float(nan)->double(non-nan)
Noticed on qemu-3.1.0 on GHC test suite where float32 comparisons didn't work on NaNs.
Here is the minimal reproducer:
```c
// cat a.c
#include <stdio.h>
#include <math.h>
#include <stdint.h>
int main() {
volatile float f1 = NAN;
volatile float f2 = NAN;
printf ("f1 (%e, %#x) >= f2 (%e, %#x): %s\n",
f1, *(volatile uint32_t*)&f1,
f2, *(volatile uint32_t*)&f2,
(f1 >= f2) ? "True"
: "False");
volatile double d = f1;
printf ("d (%e, %#llx)\n",
d, *(volatile uint64_t*)&d);
}
```
```
# incorrect execution:
$ powerpc-unknown-linux-gnu-gcc -O2 a.c -o a -static && qemu-ppc ./a
f1 (5.104236e+38, 0x7fc00000) >= f2 (5.104236e+38, 0x7fc00000): True
d (5.104236e+38, 0x47f8000000000000)
# correct execution
$ scp a timberdoodle.ppc64.dev.gentoo.org:~/; ssh timberdoodle.ppc64.dev.gentoo.org ./a
f1 (nan, 0x7fc00000) >= f2 (nan, 0x7fc00000): False
d (nan, 0x7ff8000000000000)
```
Note: qemu-ppc handled float32 extension as it was not a NaN (exp=111..1111) but a normalized number.
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