glibc/sysdeps/x86_64/multiarch/stpncpy-evex.S

#ifndef STPNCPY
# define STPNCPY	__stpncpy_evex
#endif

#define USE_AS_STPCPY
#define STRNCPY	STPNCPY
#include "strncpy-evex.S"
x86: Add support to build st{p\|r}{n}{cpy\|cat} with explicit ISA level 1. Add default ISA level selection in non-multiarch/rtld implementations. 2. Add ISA level build guards to different implementations. - I.e strcpy-avx2.S which is ISA level 3 will only build if compiled ISA level <= 3. Otherwise there is no reason to include it as we will always use one of the ISA level 4 implementations (strcpy-evex.S). 3. Refactor the ifunc selector and ifunc implementation list to use the ISA level aware wrapper macros that allow functions below the compiled ISA level (with a guranteed replacement) to be skipped. Tested with and without multiarch on x86_64 for ISA levels: {generic, x86-64-v2, x86-64-v3, x86-64-v4} And m32 with and without multiarch. 2022-07-13 23:33:01 +00:00			`#ifndef STPNCPY`
			`# define STPNCPY __stpncpy_evex`
			`#endif`

x86-64: Add strcpy family functions with 256-bit EVEX Update ifunc-strcpy.h to select the function optimized with 256-bit EVEX instructions using YMM16-YMM31 registers to avoid RTM abort with usable AVX512VL and AVX512BW since VZEROUPPER isn't needed at function exit. 2021-03-05 14:36:50 +00:00			`#define USE_AS_STPCPY`
x86: Optimize and shrink st{r\|p}{n}{cat\|cpy}-evex functions Optimizations are: 1. Use more overlapping stores to avoid branches. 2. Reduce how unrolled the aligning copies are (this is more of a code-size save, its a negative for some sizes in terms of perf). 3. Improve the loop a bit (similiar to what we do in strlen with 2x vpminu + kortest instead of 3x vpminu + kmov + test). 4. For st{r\|p}n{cat\|cpy} re-order the branches to minimize the number that are taken. Performance Changes: Times are from N = 10 runs of the benchmark suite and are reported as geometric mean of all ratios of New Implementation / Old Implementation. stpcpy-evex -> 0.922 strcat-evex -> 0.985 strcpy-evex -> 0.880 strncpy-evex -> 0.831 stpncpy-evex -> 0.780 strncat-evex -> 0.958 Code Size Changes: function -> Bytes New / Bytes Old -> Ratio strcat-evex -> 819 / 1874 -> 0.437 strcpy-evex -> 700 / 1074 -> 0.652 stpcpy-evex -> 735 / 1094 -> 0.672 strncpy-evex -> 1397 / 2611 -> 0.535 stpncpy-evex -> 1489 / 2691 -> 0.553 strncat-evex -> 1184 / 2832 -> 0.418 Notes: 1. Because of the significant difference between the implementations they are split into three files. strcpy-evex.S -> strcpy, stpcpy, strcat strncpy-evex.S -> strncpy strncat-evex.S > strncat I couldn't find a way to merge them without making the ifdefs incredibly difficult to follow. 2. All implementations can be made evex512 by including "x86-evex512-vecs.h" at the top. 3. All implementations have an optional define: `USE_EVEX_MASKED_STORE` Setting to one uses evex-masked stores for handling short strings. This saves code size and branches. It's disabled for all implementations are the moment as there are some serious drawbacks to masked stores in certain cases, but that may be fixed on future architectures. Full check passes on x86-64 and build succeeds for all ISA levels w/ and w/o multiarch. 2022-11-09 01:38:38 +00:00			`#define STRNCPY STPNCPY`
			`#include "strncpy-evex.S"`