libgcc/m68k: Fixes for soft float #93
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Just like i386, you cannot extract float or double values by using the low bits of m68k float registers. Override this hook and check that case. Signed-off-by: Keith Packard <keithp@keithp.com>
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Fix __extenddfxf2:
* Remove bogus denorm handling block which would never execute --
the converted exp value is always positive as EXCESSX > EXCESSD.
* Compute the whole significand in dl instead of doing part of it in
ldl.
* Mask off exponent from dl.l.upper so the denorm shift test
works.
* Insert the hidden one bit into dl.l.upper as needed.
Fix __truncxfdf2 denorm handling. All that is required is to shift the
significand right by the correct amount; it already has all of the
necessary bits set including the explicit one. Compute the shift
amount, then perform the wide shift across both elements of the
significand.
Fix __fixxfsi:
* The value was off by a factor of two as the significand contains
32 bits, not 31 so we need to shift by one more than the equivalent
code in __fixdfsi.
* Simplify the code having realized that the lower 32 bits of the
significand can never appear in the results.
Return positive qNaN instead of negative. For floats, qNaN is 0x7fff_ffff. For
doubles, qNaN is 0x7fff_ffff_ffff_ffff.
Return correctly signed zero on float and double divide underflow. This means
that Ld$underflow now expects d7 to contain the sign bit, just like the other
return paths.
Signed-off-by: Keith Packard <keithp@keithp.com>
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Check for non-zero denorm in __adddf3. Need to check both the upper and lower 32-bit chunks of a 64-bit float for a non-zero value when checking to see if the value is -0.
Fix __addsf3 when the sum exponent is exactly 0xff to ensure that produces infinity and not nan.
Handle converting NaN/inf values between formats.
Handle underflow and overflow when truncating.
Write a replacement for __fixxfsi so that it does not raise extra exceptions during an extra conversion from long double to double.