From 779a49bfd67793f64b43015a85bc5965fba2063f Mon Sep 17 00:00:00 2001
From: Evgenii Kliuchnikov <eustas@google.com>
Date: Thu, 20 Jul 2023 04:18:18 -0700
Subject: [PATCH] bake in runtime constant

PiperOrigin-RevId: 549590409
---
 c/enc/hash_longest_match64_inc.h | 14 ++++----------
 c/enc/params.h                   |  1 -
 c/enc/quality.h                  |  1 -
 3 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/c/enc/hash_longest_match64_inc.h b/c/enc/hash_longest_match64_inc.h
index d02435e76..da75949ea 100644
--- a/c/enc/hash_longest_match64_inc.h
+++ b/c/enc/hash_longest_match64_inc.h
@@ -21,8 +21,8 @@ static BROTLI_INLINE size_t FN(StoreLookahead)(void) { return 8; }
 
 /* HashBytes is the function that chooses the bucket to place the address in. */
 static BROTLI_INLINE uint32_t FN(HashBytes)(const uint8_t* BROTLI_RESTRICT data,
-                                            const uint64_t mask,
                                             const int shift) {
+  const uint64_t mask = (~((uint64_t)0U)) >> 24;  /* Use only 5 bytes. */
   const uint64_t h = (BROTLI_UNALIGNED_LOAD64LE(data) & mask) * kHashMul64Long;
   /* The higher bits contain more mixture from the multiplication,
      so we take our results from there. */
@@ -37,8 +37,6 @@ typedef struct HashLongestMatch {
   size_t block_size_;
   /* Left-shift for computing hash bucket index from hash value. */
   int hash_shift_;
-  /* Mask for selecting the next 4-8 bytes of input */
-  uint64_t hash_mask_;
   /* Mask for accessing entries in a block (in a ring-buffer manner). */
   uint32_t block_mask_;
 
@@ -64,7 +62,6 @@ static void FN(Initialize)(
 
   BROTLI_UNUSED(params);
   self->hash_shift_ = 64 - common->params.bucket_bits;
-  self->hash_mask_ = (~((uint64_t)0U)) >> (64 - 8 * common->params.hash_len);
   self->bucket_size_ = (size_t)1 << common->params.bucket_bits;
   self->block_bits_ = common->params.block_bits;
   self->block_size_ = (size_t)1 << common->params.block_bits;
@@ -84,8 +81,7 @@ static void FN(Prepare)(
   if (one_shot && input_size <= partial_prepare_threshold) {
     size_t i;
     for (i = 0; i < input_size; ++i) {
-      const uint32_t key = FN(HashBytes)(&data[i], self->hash_mask_,
-                                         self->hash_shift_);
+      const uint32_t key = FN(HashBytes)(&data[i], self->hash_shift_);
       num[key] = 0;
     }
   } else {
@@ -111,8 +107,7 @@ static BROTLI_INLINE void FN(Store)(
     const size_t mask, const size_t ix) {
   uint16_t* BROTLI_RESTRICT num = self->num_;
   uint32_t* BROTLI_RESTRICT buckets = self->buckets_;
-  const uint32_t key = FN(HashBytes)(&data[ix & mask], self->hash_mask_,
-                                     self->hash_shift_);
+  const uint32_t key = FN(HashBytes)(&data[ix & mask], self->hash_shift_);
   const size_t minor_ix = num[key] & self->block_mask_;
   const size_t offset = minor_ix + (key << self->block_bits_);
   ++num[key];
@@ -217,8 +212,7 @@ static BROTLI_INLINE void FN(FindLongestMatch)(
     }
   }
   {
-    const uint32_t key = FN(HashBytes)(
-        &data[cur_ix_masked], self->hash_mask_, self->hash_shift_);
+    const uint32_t key = FN(HashBytes)(&data[cur_ix_masked], self->hash_shift_);
     uint32_t* BROTLI_RESTRICT bucket = &buckets[key << self->block_bits_];
     const size_t down =
         (num[key] > self->block_size_) ?
diff --git a/c/enc/params.h b/c/enc/params.h
index baeb31967..78b2ab608 100644
--- a/c/enc/params.h
+++ b/c/enc/params.h
@@ -17,7 +17,6 @@ typedef struct BrotliHasherParams {
   int type;
   int bucket_bits;
   int block_bits;
-  int hash_len;
   int num_last_distances_to_check;
 } BrotliHasherParams;
 
diff --git a/c/enc/quality.h b/c/enc/quality.h
index 99891b479..4415a54ff 100644
--- a/c/enc/quality.h
+++ b/c/enc/quality.h
@@ -133,7 +133,6 @@ static BROTLI_INLINE void ChooseHasher(const BrotliEncoderParams* params,
     hparams->type = 6;
     hparams->block_bits = params->quality - 1;
     hparams->bucket_bits = 15;
-    hparams->hash_len = 5;
     hparams->num_last_distances_to_check =
         params->quality < 7 ? 4 : params->quality < 9 ? 10 : 16;
   } else {