huntedbytheirsandSisyphus
6854c7771d
Suppress clang-analyzer-security buffer-handling diagnostics on the plan-mandated __builtin_memcpy word loads and bugprone swappable- parameter diagnostics on the C-standard signatures; wrap the autoconf substitution tokens in clang-format off/on (the space clang-format wants before the closing @ would break config.status substitution). Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <[email protected]>
53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <string.h>
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/*
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* Copy n bytes from src to dst. The regions must not overlap (restrict).
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* Word-at-a-time: copy whole unsigned long words once dst is aligned, with
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* a byte head and tail. Word loads and stores go through __builtin_memcpy
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* so unaligned src is handled without undefined behavior.
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*
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* The word-copy loop below is the canonical memcpy idiom; GCC's
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* -ftree-loop-distribute-patterns (on by default at -O2 and -O3) rewrites
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* it into a call to memcpy() — this very function — causing infinite
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* self-recursion and stack overflow. Disable that one transformation for
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* this function only.
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*/
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__attribute__((optimize("no-tree-loop-distribute-patterns"))) void *
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memcpy(void *restrict dst, const void *restrict src, size_t n) // NOLINT(bugprone-*)
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{
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const unsigned long word = sizeof(unsigned long);
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unsigned char *d = dst;
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const unsigned char *s = src;
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/* Copy the unaligned head byte-wise. */
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for (; (unsigned long)d % word != 0 && n != 0; n--)
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{
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*d++ = *s++;
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}
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/* Copy whole words. */
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while (n >= word)
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{
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unsigned long w;
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__builtin_memcpy(&w, s, sizeof w); // NOLINT(clang-analyzer-security.insecureAPI.*)
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__builtin_memcpy(d, &w, sizeof w); // NOLINT(clang-analyzer-security.insecureAPI.*)
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d += word;
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s += word;
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n -= word;
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}
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/* Copy the remaining tail byte-wise. */
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while (n != 0)
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{
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*d++ = *s++;
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n--;
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}
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return dst;
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}
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