Make AARCH64 harder, better, faster, stronger

- Perform some housekeeping on scalar math function code
- Import ARM's Optimized Routines for SIMD string processing
- Upgrade to latest Chromium zlib and enable more SIMD optimizations

third_party/zlib/slide_hash_simd.inc

@@ -0,0 +1,117 @@
+// clang-format off
+/* slide_hash_simd.h
+ *
+ * Copyright 2022 The Chromium Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the Chromium source repository LICENSE file.
+ */
+
+#ifndef SLIDE_HASH_SIMD_H
+#define SLIDE_HASH_SIMD_H
+
+#include "third_party/zlib/deflate.internal.h"
+
+#ifndef INLINE
+#if defined(_MSC_VER) && !defined(__clang__)
+#define INLINE __inline
+#else
+#define INLINE inline
+#endif
+#endif
+
+#if defined(CPU_NO_SIMD)
+
+#error SIMD has been disabled for your build target
+
+#elif defined(DEFLATE_SLIDE_HASH_SSE2)
+
+#include "third_party/intel/emmintrin.internal.h"  /* SSE2 */
+
+#define Z_SLIDE_INIT_SIMD(wsize) _mm_set1_epi16((ush)(wsize))
+
+#define Z_SLIDE_HASH_SIMD(table, size, vector_wsize) \
+    for (const Posf* const end = table + size; table != end;) { \
+        __m128i vO = _mm_loadu_si128((__m128i *)(table + 0)); \
+        vO = _mm_subs_epu16(vO, vector_wsize); \
+        _mm_storeu_si128((__m128i *)(table + 0), vO); \
+        table += 8; \
+    }
+
+typedef __m128i z_vec128i_u16x8_t;
+
+#elif defined(DEFLATE_SLIDE_HASH_NEON)
+
+#include "third_party/aarch64/arm_neon.h"  /* NEON */
+
+#define Z_SLIDE_INIT_SIMD(wsize) vdupq_n_u16((ush)(wsize))
+
+#define Z_SLIDE_HASH_SIMD(table, size, vector_wsize) \
+    for (const Posf* const end = table + size; table != end;) { \
+        uint16x8_t vO = vld1q_u16(table + 0); \
+        uint16x8_t v8 = vld1q_u16(table + 8); \
+        vO = vqsubq_u16(vO, vector_wsize); \
+        v8 = vqsubq_u16(v8, vector_wsize); \
+        vst1q_u16(table + 0, vO); \
+        vst1q_u16(table + 8, v8); \
+        table += 8 + 8; \
+    }
+
+typedef uint16x8_t z_vec128i_u16x8_t;
+
+#else
+
+#error slide_hash_simd is not defined for your build target
+
+#endif
+
+/* ===========================================================================
+ * Slide the hash table when sliding the window down (could be avoided with 32
+ * bit values at the expense of memory usage). We slide even when level == 0 to
+ * keep the hash table consistent if we switch back to level > 0 later.
+ */
+local INLINE void slide_hash_simd(
+    Posf *head, Posf *prev, const uInt w_size, const uInt hash_size) {
+    /*
+     * The SIMD implementation of the hash table slider assumes:
+     *
+     * 1. hash chain offset is 2 bytes. Should be true as Pos is "ush" type.
+     */
+    Assert(sizeof(Pos) == 2, "Pos type size error: should be 2 bytes");
+    Assert(sizeof(ush) == 2, "ush type size error: should be 2 bytes");
+
+    Assert(hash_size <= (1 << 16), "Hash table maximum size error");
+    Assert(hash_size >= (1 << 8), "Hash table minimum size error");
+    Assert(w_size == (ush)w_size, "Prev table size error");
+
+    /*
+     * 2. The hash & prev table sizes are a multiple of 32 bytes (256 bits),
+     * since the NEON table slider moves two 128-bit items per loop (loop is
+     * unrolled on NEON for performance, see http://crbug.com/863257).
+     */
+    Assert(!((hash_size * sizeof(head[0])) & (32 - 1)),
+        "Hash table size error: should be a multiple of 32 bytes");
+    Assert(!((w_size * sizeof(prev[0])) & (32 - 1)),
+        "Prev table size error: should be a multiple of 32 bytes");
+
+    /*
+     * Duplicate (ush)w_size in each uint16_t component of a 128-bit vector.
+     */
+    const z_vec128i_u16x8_t vec_wsize = Z_SLIDE_INIT_SIMD(w_size);
+
+    /*
+     * Slide {head,prev} hash chain values: subtracts (ush)w_size from every
+     * value with a saturating SIMD subtract, to clamp the result to 0(NIL),
+     * to implement slide_hash() `(m >= wsize ? m - wsize : NIL);` code.
+     */
+    Z_SLIDE_HASH_SIMD(head, hash_size, vec_wsize);
+#ifndef FASTEST
+    Z_SLIDE_HASH_SIMD(prev, w_size, vec_wsize);
+#endif
+
+}
+
+#undef z_vec128i_u16x8_t
+#undef Z_SLIDE_HASH_SIMD
+#undef Z_SLIDE_INIT_SIMD
+
+#endif  /* SLIDE_HASH_SIMD_H */