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path: root/src/math/i386/log1pf.s
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2020-02-06fix excess precision in return value of i386 log-family functionsRich Felker1-0/+4
2019-08-05fix x87 stack imbalance in corner cases of i386 math asmRich Felker1-5/+2
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.
2013-08-15math: fix x86 asin, atan, exp, log1p to raise underflowSzabolcs Nagy1-0/+10
underflow is raised by an inexact subnormal float store, since subnormal operations are slow, check the underflow flag and skip the store if it's already raised
2012-03-19asm for log1pRich Felker1-0/+15