diff options
Diffstat (limited to 'debian/patches/endian-hash.diff')
| -rw-r--r-- | debian/patches/endian-hash.diff | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/debian/patches/endian-hash.diff b/debian/patches/endian-hash.diff new file mode 100644 index 00000000..01c1b6b0 --- /dev/null +++ b/debian/patches/endian-hash.diff @@ -0,0 +1,111 @@ +From: Benjamin Barenblat <bbaren@google.com> +Subject: Remove endian-sensitivity from hash slow path +Forwarded: yes +Applied-Upstream: https://github.com/abseil/abseil-cpp/commit/9c6a50fdd80bb39fabd95faeda84f04062685ff3 + +Prior to this commit, the Abseil hash fast path was endian-agnostic, but +the slow path assumed a little-endian platform. Change the slow path to +be endian-correct, ensuring that values produced by the fast and slow +paths are equal even on big-endian systems. + +The author works at Google. Upstream applied this patch as Piper revision +355424258 and exported it to GitHub; the Applied-Upstream URL above points to +the exported commit. + +--- a/absl/hash/BUILD.bazel ++++ b/absl/hash/BUILD.bazel +@@ -37,6 +37,7 @@ cc_library(name = "hash", + linkopts = ABSL_DEFAULT_LINKOPTS, + deps = [ + ":city", ++ "//absl/base:config", + "//absl/base:core_headers", + "//absl/base:endian", + "//absl/container:fixed_array", +--- a/absl/hash/CMakeLists.txt ++++ b/absl/hash/CMakeLists.txt +@@ -25,6 +25,7 @@ absl_cc_library(NAME hash + COPTS + ${ABSL_DEFAULT_COPTS} + DEPS ++ absl::config + absl::core_headers + absl::endian + absl::fixed_array +--- a/absl/hash/internal/hash.h ++++ b/absl/hash/internal/hash.h +@@ -38,7 +38,8 @@ + #include <utility> + #include <vector> + +-#include "absl/base/internal/endian.h" ++#include "absl/base/config.h" ++#include "absl/base/internal/unaligned_access.h" + #include "absl/base/port.h" + #include "absl/container/fixed_array.h" + #include "absl/meta/type_traits.h" +@@ -804,26 +805,54 @@ class ABSL_DLL CityHashState + size_t len); + + // Reads 9 to 16 bytes from p. +- // The first 8 bytes are in .first, the rest (zero padded) bytes are in +- // .second. ++ // The least significant 8 bytes are in .first, the rest (zero padded) bytes ++ // are in .second. + static std::pair<uint64_t, uint64_t> Read9To16(const unsigned char* p, + size_t len) { +- uint64_t high = little_endian::Load64(p + len - 8); +- return {little_endian::Load64(p), high >> (128 - len * 8)}; ++ uint64_t low_mem = absl::base_internal::UnalignedLoad64(p); ++ uint64_t high_mem = absl::base_internal::UnalignedLoad64(p + len - 8); ++#ifdef ABSL_IS_LITTLE_ENDIAN ++ uint64_t most_significant = high_mem; ++ uint64_t least_significant = low_mem; ++#else ++ uint64_t most_significant = low_mem; ++ uint64_t least_significant = high_mem; ++#endif ++ return {least_significant, most_significant >> (128 - len * 8)}; + } + + // Reads 4 to 8 bytes from p. Zero pads to fill uint64_t. + static uint64_t Read4To8(const unsigned char* p, size_t len) { +- return (static_cast<uint64_t>(little_endian::Load32(p + len - 4)) +- << (len - 4) * 8) | +- little_endian::Load32(p); ++ uint32_t low_mem = absl::base_internal::UnalignedLoad32(p); ++ uint32_t high_mem = absl::base_internal::UnalignedLoad32(p + len - 4); ++#ifdef ABSL_IS_LITTLE_ENDIAN ++ uint32_t most_significant = high_mem; ++ uint32_t least_significant = low_mem; ++#else ++ uint32_t most_significant = low_mem; ++ uint32_t least_significant = high_mem; ++#endif ++ return (static_cast<uint64_t>(most_significant) << (len - 4) * 8) | ++ least_significant; + } + + // Reads 1 to 3 bytes from p. Zero pads to fill uint32_t. + static uint32_t Read1To3(const unsigned char* p, size_t len) { +- return static_cast<uint32_t>((p[0]) | // +- (p[len / 2] << (len / 2 * 8)) | // +- (p[len - 1] << ((len - 1) * 8))); ++ unsigned char mem0 = p[0]; ++ unsigned char mem1 = p[len / 2]; ++ unsigned char mem2 = p[len - 1]; ++#ifdef ABSL_IS_LITTLE_ENDIAN ++ unsigned char significant2 = mem2; ++ unsigned char significant1 = mem1; ++ unsigned char significant0 = mem0; ++#else ++ unsigned char significant2 = mem0; ++ unsigned char significant1 = mem1; ++ unsigned char significant0 = mem2; ++#endif ++ return static_cast<uint32_t>(significant0 | // ++ (significant1 << (len / 2 * 8)) | // ++ (significant2 << ((len - 1) * 8))); + } + + ABSL_ATTRIBUTE_ALWAYS_INLINE static uint64_t Mix(uint64_t state, uint64_t v) { |