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2018-10-15arm: add single instruction fmaSzabolcs Nagy2-0/+30
vfma is available in the vfpv4 fpu and above, the ACLE standard feature test for double precision hardware fma support is __ARM_FEATURE_FMA && __ARM_FP&8 we need further checks to work around clang bugs (fixed in clang >=7.0) && !__SOFTFP__ because __ARM_FP is defined even with -mfloat-abi=soft && !BROKEN_VFP_ASM to disable the single precision code when inline asm handling is broken. For runtime selection the HWCAP_ARM_VFPv4 hwcap flag can be used, but that requires further work.
2016-02-19work around regression building for armhf with clang (compiler bug)Rich Felker2-2/+2
commit e4355bd6bec89688e8c739cd7b4c76e675643dca moved the math asm from external source files to inline asm, but unfortunately, all current releases of clang use the wrong inline asm constraint codes for float and double ("w" and "P" instead of "t" and "w", respectively). this patch adds detection for the bug in configure, and, for now, just disables the affected asm on broken clang versions.
2016-02-18improve macro logic for enabling arm math asmRich Felker2-2/+2
in order to take advantage of the fpu in -mfloat-abi=softfp mode, the __VFP_FP__ (presence of vfp fpu) was checked instead of checking for __ARM_PCS_VFP (hardfloat EABI variant). however, the latter macro is the one that's actually specified by the ABI documents rather than being compiler-specific, and should also be checked in case __VFP_FP__ is not defined on some compilers or some configurations.
2016-01-20replace armhf math asm source files with inline asmRich Felker4-0/+60
this makes it possible to inline them with LTO, and is the simplest approach to eliminating the use of .sub files. this also makes VFP sqrt available for use with the standard EABI (plain arm rather than armhf subarch) when libc is built with -mfloat-abi=softfp. the same could have been done for fabs, but when the argument and return value are in integer registers, moving to VFP registers and back is almost certainly more costly than a simple integer operation.