Export of internal Abseil changes

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3a9b4e8e5ecba532db5cc4ac12d12660307ce9fb by Derek Mauro <dmauro@google.com>:

Use the Bazel @platforms repository for platform constraints
Fixes #1000

PiperOrigin-RevId: 390644226

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b34e4d2f8a86b54bd483ec4c9c3dd781ad2d8b68 by Abseil Team <absl-team@google.com>:

debugging: add some handling for RISC-V

The RISC-V architecture uses a downward growing stack and can host Linux using
ELF files.  Adjust a few sites accordingly to indicate how to handle the RISC-V
architecture.

PiperOrigin-RevId: 390631894

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5fa3a0961bf3dd0799c048956a0128f7b8113f1e by Samuel Benzaquen <sbenza@google.com>:

Rename the buffer hash function to LowLevelHash.
Although it started as wyhash, it will depart from it so it does not make sense
to keep the name.

PiperOrigin-RevId: 390483506

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2e7867a2301d58ad4cd5abcaa5fd6f0db973ae7b by Abseil Team <absl-team@google.com>:

This is an internal change.

PiperOrigin-RevId: 390349746
GitOrigin-RevId: 3a9b4e8e5ecba532db5cc4ac12d12660307ce9fb
Change-Id: I322c3762552a2107e6c6b108c25c01e5efa8aecd

1 files changed, 0 insertions, 111 deletions

diff --git a/absl/hash/internal/wyhash.cc b/absl/hash/internal/wyhash.cc
deleted file mode 100644
index 642bde43..00000000
--- a/absl/hash/internal/wyhash.cc
+++ /dev/null
@@ -1,111 +0,0 @@
-// Copyright 2020 The Abseil Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "absl/hash/internal/wyhash.h"
-
-#include "absl/base/internal/unaligned_access.h"
-#include "absl/numeric/int128.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace hash_internal {
-
-static uint64_t WyhashMix(uint64_t v0, uint64_t v1) {
-  absl::uint128 p = v0;
-  p *= v1;
-  return absl::Uint128Low64(p) ^ absl::Uint128High64(p);
-}
-
-uint64_t Wyhash(const void* data, size_t len, uint64_t seed,
-                const uint64_t salt[]) {
-  const uint8_t* ptr = static_cast<const uint8_t*>(data);
-  uint64_t starting_length = static_cast<uint64_t>(len);
-  uint64_t current_state = seed ^ salt[0];
-
-  if (len > 64) {
-    // If we have more than 64 bytes, we're going to handle chunks of 64
-    // bytes at a time. We're going to build up two separate hash states
-    // which we will then hash together.
-    uint64_t duplicated_state = current_state;
-
-    do {
-      uint64_t a = absl::base_internal::UnalignedLoad64(ptr);
-      uint64_t b = absl::base_internal::UnalignedLoad64(ptr + 8);
-      uint64_t c = absl::base_internal::UnalignedLoad64(ptr + 16);
-      uint64_t d = absl::base_internal::UnalignedLoad64(ptr + 24);
-      uint64_t e = absl::base_internal::UnalignedLoad64(ptr + 32);
-      uint64_t f = absl::base_internal::UnalignedLoad64(ptr + 40);
-      uint64_t g = absl::base_internal::UnalignedLoad64(ptr + 48);
-      uint64_t h = absl::base_internal::UnalignedLoad64(ptr + 56);
-
-      uint64_t cs0 = WyhashMix(a ^ salt[1], b ^ current_state);
-      uint64_t cs1 = WyhashMix(c ^ salt[2], d ^ current_state);
-      current_state = (cs0 ^ cs1);
-
-      uint64_t ds0 = WyhashMix(e ^ salt[3], f ^ duplicated_state);
-      uint64_t ds1 = WyhashMix(g ^ salt[4], h ^ duplicated_state);
-      duplicated_state = (ds0 ^ ds1);
-
-      ptr += 64;
-      len -= 64;
-    } while (len > 64);
-
-    current_state = current_state ^ duplicated_state;
-  }
-
-  // We now have a data `ptr` with at most 64 bytes and the current state
-  // of the hashing state machine stored in current_state.
-  while (len > 16) {
-    uint64_t a = absl::base_internal::UnalignedLoad64(ptr);
-    uint64_t b = absl::base_internal::UnalignedLoad64(ptr + 8);
-
-    current_state = WyhashMix(a ^ salt[1], b ^ current_state);
-
-    ptr += 16;
-    len -= 16;
-  }
-
-  // We now have a data `ptr` with at most 16 bytes.
-  uint64_t a = 0;
-  uint64_t b = 0;
-  if (len > 8) {
-    // When we have at least 9 and at most 16 bytes, set A to the first 64
-    // bits of the input and B to the last 64 bits of the input. Yes, they will
-    // overlap in the middle if we are working with less than the full 16
-    // bytes.
-    a = absl::base_internal::UnalignedLoad64(ptr);
-    b = absl::base_internal::UnalignedLoad64(ptr + len - 8);
-  } else if (len > 3) {
-    // If we have at least 4 and at most 8 bytes, set A to the first 32
-    // bits and B to the last 32 bits.
-    a = absl::base_internal::UnalignedLoad32(ptr);
-    b = absl::base_internal::UnalignedLoad32(ptr + len - 4);
-  } else if (len > 0) {
-    // If we have at least 1 and at most 3 bytes, read all of the provided
-    // bits into A, with some adjustments.
-    a = ((ptr[0] << 16) | (ptr[len >> 1] << 8) | ptr[len - 1]);
-    b = 0;
-  } else {
-    a = 0;
-    b = 0;
-  }
-
-  uint64_t w = WyhashMix(a ^ salt[1], b ^ current_state);
-  uint64_t z = salt[1] ^ starting_length;
-  return WyhashMix(w, z);
-}
-
-}  // namespace hash_internal
-ABSL_NAMESPACE_END
-}  // namespace absl