Disable ubsan for benign unaligned access in crc_memcpy

PiperOrigin-RevId: 615160537
Change-Id: I29070c898104c55e6563eed0eef7397441bef1d7

absl/crc/internal/crc_memcpy_x86_arm_combined.cc

@@ -52,6 +52,7 @@
 #include <cstring>
 #include <memory>
 
+#include "absl/base/attributes.h"
 #include "absl/base/config.h"
 #include "absl/base/optimization.h"
 #include "absl/base/prefetch.h"
@@ -88,9 +89,11 @@ inline crc32c_t ShortCrcCopy(char* dst, const char* src, std::size_t length,
 constexpr size_t kIntLoadsPerVec = sizeof(V128) / sizeof(uint64_t);
 
 // Common function for copying the tails of multiple large regions.
+// Disable ubsan for benign unaligned access. See b/254108538.
 template <size_t vec_regions, size_t int_regions>
-inline void LargeTailCopy(crc32c_t* crcs, char** dst, const char** src,
-                          size_t region_size, size_t copy_rounds) {
+ABSL_ATTRIBUTE_NO_SANITIZE_UNDEFINED inline void LargeTailCopy(
+    crc32c_t* crcs, char** dst, const char** src, size_t region_size,
+    size_t copy_rounds) {
   std::array<V128, vec_regions> data;
   std::array<uint64_t, kIntLoadsPerVec * int_regions> int_data;
 
@@ -155,8 +158,10 @@ class AcceleratedCrcMemcpyEngine : public CrcMemcpyEngine {
                    std::size_t length, crc32c_t initial_crc) const override;
 };
 
+// Disable ubsan for benign unaligned access. See b/254108538.
 template <size_t vec_regions, size_t int_regions>
-crc32c_t AcceleratedCrcMemcpyEngine<vec_regions, int_regions>::Compute(
+ABSL_ATTRIBUTE_NO_SANITIZE_UNDEFINED crc32c_t
+AcceleratedCrcMemcpyEngine<vec_regions, int_regions>::Compute(
     void* __restrict dst, const void* __restrict src, std::size_t length,
     crc32c_t initial_crc) const {
   constexpr std::size_t kRegions = vec_regions + int_regions;