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* fix build regression in i386 asm for atan2, atan2fRich Felker2019-08-051-1/+1
| | | | | commit f3ed8bfe8a82af1870ddc8696ed4cc1d5aa6b441 inadvertently removed labels that were still needed.
* fix x87 stack imbalance in corner cases of i386 math asmRich Felker2019-08-051-4/+1
| | | | | | | | | | | | | | | | | | | | | | | commit 31c5fb80b9eae86f801be4f46025bc6532a554c5 introduced underflow code paths for the i386 math asm, along with checks on the fpu status word to skip the underflow-generation instructions if the underflow flag was already raised. unfortunately, at least one such path, in log1p, returned with 2 items on the x87 stack rather than just 1 item for the return value. this is a violation of the ABI's calling convention, and could cause subsequent floating point code to produce NANs due to x87 stack overflow. if floating point results are used in flow control, this can lead to runaway wrong code execution. rather than reviewing each "underflow already raised" code path for correctness, remove them all. they're likely slower than just performing the underflow code unconditionally, and significantly more complex. all of this code should be ripped out and replaced by C source files with inline asm. doing so would preclude this kind of error by having the compiler perform all x87 stack register allocation and stack manipulation, and would produce comparable or better code. however such a change is a much larger project.
* math: fix i386 atan2.s to raise underflow for subnormal resultsSzabolcs Nagy2013-08-151-1/+13
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* asm for inverse trig functionsRich Felker2012-03-191-0/+7
unlike trig functions, these are easy to do in asm because they do not involve (arbitrary-precision) argument reduction. fpatan automatically takes care of domain issues, and in asin and acos, fsqrt takes care of them for us.