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by shakna
1968 days ago
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> Support for Annex F (IEEE-754 / IEC 559) of C99/C11 > The Clang compiler does not support IEC 559 math functionality. Clang also does not control and honor the definition of __STDC_IEC_559__ macro. Under specific options such as -Ofast and -ffast-math, the compiler will enable a range of optimizations that provide faster mathematical operations that may not conform to the IEEE-754 specifications. The macro __STDC_IEC_559__ value may be defined but ignored when these faster optimizations are enabled. If you make use of Clang, you won't find support for Annex F, and in point of fact you can't even macro check to see if it even will support Annex F. The story with GCC is... More complicated. It guarantees it'll follow Annex F for only some operations [0]. So the upshot is... Most people can't tell when and how Annex F might be followed. [0] https://gcc.gnu.org/onlinedocs/gcc-7.4.0/gcc/Floating-point-... |
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