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Fix tan returning -nan for inputs where abs(x) >= 2^63 #5114

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dlang-bot merged 1 commit into from
Jun 27, 2017
Merged

Fix tan returning -nan for inputs where abs(x) >= 2^63 #5114

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20 changes: 16 additions & 4 deletions std/math.d
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Original file line number Diff line number Diff line change
Expand Up @@ -768,10 +768,9 @@ real tan(real x) @trusted pure nothrow @nogc
jc trigerr ; // x is NAN, infinity, or empty
// 387's can handle subnormals
SC18: fptan ;
fstp ST(0) ; // dump X, which is always 1
fstsw AX ;
sahf ;
jnp Lret ; // C2 = 1 (x is out of range)
jnp Clear1 ; // C2 = 1 (x is out of range)

// Do argument reduction to bring x into range
fldpi ;
Expand All @@ -789,6 +788,10 @@ trigerr:
}
return real.nan;

Clear1: asm pure nothrow @nogc{
fstp ST(0) ; // dump X, which is always 1
}

Lret: {}
}
else version(D_InlineAsm_X86_64)
Expand All @@ -815,10 +818,9 @@ Lret: {}
jnz trigerr ; // x is NAN, infinity, or empty
// 387's can handle subnormals
SC18: fptan ;
fstp ST(0) ; // dump X, which is always 1
fstsw AX ;
test AH,4 ;
jz Lret ; // C2 = 1 (x is out of range)
jz Clear1 ; // C2 = 1 (x is out of range)

// Do argument reduction to bring x into range
fldpi ;
Expand All @@ -837,6 +839,10 @@ trigerr:
}
return real.nan;

Clear1: asm pure nothrow @nogc{
fstp ST(0) ; // dump X, which is always 1
}

Lret: {}
}
else
Expand Down Expand Up @@ -7174,6 +7180,12 @@ deprecated("Phobos1 math functions are deprecated, use isInfinity ") alias isinf

real r = tan(-2.0L);
assert(fabs(r - 2.18504f) < .00001);

// Verify correct behavior for large inputs
assert(!isNaN(tan(0x1p63)));
assert(!isNaN(tan(0x1p300L)));
assert(!isNaN(tan(-0x1p63)));
assert(!isNaN(tan(-0x1p300L)));
}

@safe pure nothrow unittest
Expand Down