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target-mips: Implement correct NaN propagation rules

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Implement the correct NaN propagation rules for MIPS targets by
providing an appropriate pickNaN function.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2011-01-06 15:38:19 +01:00
parent 1f398e0825
commit 084d19ba71
1 changed files with 27 additions and 0 deletions
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27
fpu/softfloat-specialize.h
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@ -192,6 +192,33 @@ static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
return 1;
}
}
#elif defined(TARGET_MIPS)
static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
flag aIsLargerSignificand)
{
/* According to MIPS specifications, if one of the two operands is
* a sNaN, a new qNaN has to be generated. This is done in
* floatXX_maybe_silence_nan(). For qNaN inputs the specifications
* says: "When possible, this QNaN result is one of the operand QNaN
* values." In practice it seems that most implementations choose
* the first operand if both operands are qNaN. In short this gives
* the following rules:
* 1. A if it is signaling
* 2. B if it is signaling
* 3. A (quiet)
* 4. B (quiet)
* A signaling NaN is always silenced before returning it.
*/
if (aIsSNaN) {
return 0;
} else if (bIsSNaN) {
return 1;
} else if (aIsQNaN) {
return 0;
} else {
return 1;
}
}
#else
static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
flag aIsLargerSignificand)