Revert of Add support for NEON intrinsics to speed up texture compression. We can

src/opts/SkTextureCompression_opts_neon.cpp

-/*
- * Copyright 2014
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "SkTextureCompressor.h"
-#include "SkTextureCompression_opts.h"
-
-#include <arm_neon.h>
-
-// Converts indices in each of the four bits of the register from
-// 0, 1, 2, 3, 4, 5, 6, 7
-// to
-// 3, 2, 1, 0, 4, 5, 6, 7
-//
-// A more detailed explanation can be found in SkTextureCompressor::convert_indices
-static inline uint8x16_t convert_indices(const uint8x16_t &x) {
-    static const int8x16_t kThree = {
-        0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
-        0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
-    };
-
-    static const int8x16_t kZero = {
-        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-    };
-    
-    // Take top three bits
-    int8x16_t sx = vreinterpretq_s8_u8(x);
-
-    // Negate ...
-    sx = vnegq_s8(sx);
-
-    // Add three...
-    sx = vaddq_s8(sx, kThree);
-
-    // Generate negatives mask
-    const int8x16_t mask = vreinterpretq_s8_u8(vcltq_s8(sx, kZero));
-
-    // Absolute value
-    sx = vabsq_s8(sx);
-
-    // Add three to the values that were negative...
-    return vreinterpretq_u8_s8(vaddq_s8(sx, vandq_s8(mask, kThree)));
-}
-
-template<unsigned shift>
-static inline uint64x2_t shift_swap(const uint64x2_t &x, const uint64x2_t &mask) {
-    uint64x2_t t = vandq_u64(mask, veorq_u64(x, vshrq_n_u64(x, shift)));
-    return veorq_u64(x, veorq_u64(t, vshlq_n_u64(t, shift)));
-}
-
-static inline uint64x2_t pack_indices(const uint64x2_t &x) {
-    // x: 00 a e 00 b f 00 c g 00 d h 00 i m 00 j n 00 k o 00 l p
-
-    static const uint64x2_t kMask1 = { 0x3FC0003FC00000ULL, 0x3FC0003FC00000ULL };
-    uint64x2_t ret = shift_swap<10>(x, kMask1);
-
-    // x: b f 00 00 00 a e c g i m 00 00 00 d h j n 00 k o 00 l p
-    static const uint64x2_t kMask2 = { (0x3FULL << 52), (0x3FULL << 52) };
-    static const uint64x2_t kMask3 = { (0x3FULL << 28), (0x3FULL << 28) };
-    const uint64x2_t x1 = vandq_u64(vshlq_n_u64(ret, 52), kMask2);
-    const uint64x2_t x2 = vandq_u64(vshlq_n_u64(ret, 20), kMask3);
-    ret = vshrq_n_u64(vorrq_u64(ret, vorrq_u64(x1, x2)), 16);
-
-    // x: 00 00 00 00 00 00 00 00 b f l p a e c g i m k o d h j n
-
-    static const uint64x2_t kMask4 = { 0xFC0000ULL, 0xFC0000ULL };
-    ret = shift_swap<6>(ret, kMask4);
-
-#if defined (SK_CPU_BENDIAN)
-    // x: 00 00 00 00 00 00 00 00 b f l p a e i m c g k o d h j n
-
-    static const uint64x2_t kMask5 = { 0x3FULL, 0x3FULL };
-    ret = shift_swap<36>(ret, kMask5);
-
-    // x: 00 00 00 00 00 00 00 00 b f j n a e i m c g k o d h l p
-
-    static const uint64x2_t kMask6 = { 0xFFF000000ULL, 0xFFF000000ULL };
-    ret = shift_swap<12>(ret, kMask6);
-#else
-    // x: 00 00 00 00 00 00 00 00 c g i m d h l p b f j n a e k o
-
-    static const uint64x2_t kMask5 = { 0xFC0ULL, 0xFC0ULL };
-    ret = shift_swap<36>(ret, kMask5);
-
-    // x: 00 00 00 00 00 00 00 00 a e i m d h l p b f j n c g k o
-
-    static const uint64x2_t kMask6 = { (0xFFFULL << 36), (0xFFFULL << 36) };
-    static const uint64x2_t kMask7 = { 0xFFFFFFULL, 0xFFFFFFULL };
-    static const uint64x2_t kMask8 = { 0xFFFULL, 0xFFFULL };
-    const uint64x2_t y1 = vandq_u64(ret, kMask6);
-    const uint64x2_t y2 = vshlq_n_u64(vandq_u64(ret, kMask7), 12);
-    const uint64x2_t y3 = vandq_u64(vshrq_n_u64(ret, 24), kMask8);
-    ret = vorrq_u64(y1, vorrq_u64(y2, y3));
-#endif
-
-    // x: 00 00 00 00 00 00 00 00 a e i m b f j n c g k o d h l p
-
-    // Set the header
-    static const uint64x2_t kHeader = { 0x8490000000000000ULL, 0x8490000000000000ULL };
-    return vorrq_u64(kHeader, ret);
-}
-
-// Takes a row of alpha values and places the most significant three bits of each byte into
-// the least significant bits of the same byte
-static inline uint8x16_t make_index_row(const uint8x16_t &x) {
-    static const uint8x16_t kTopThreeMask = {
-        0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0,
-        0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0, 0xE0,
-    };
-    return vshrq_n_u8(vandq_u8(x, kTopThreeMask), 5);
-}
-
-// Returns true if all of the bits in x are 0.
-static inline bool is_zero(uint8x16_t x) {
-// First experiments say that this is way slower than just examining the lanes
-// but it might need a little more investigation.
-#if 0
-    // This code path tests the system register for overflow. We trigger
-    // overflow by adding x to a register with all of its bits set. The
-    // first instruction sets the bits.
-    int reg;
-    asm ("VTST.8   %%q0, %q1, %q1\n"
-         "VQADD.u8 %q1, %%q0\n"
-         "VMRS     %0, FPSCR\n"
-         : "=r"(reg) : "w"(vreinterpretq_f32_u8(x)) : "q0", "q1");
-
-    // Bit 21 corresponds to the overflow flag.
-    return reg & (0x1 << 21);
-#else
-    const uint64x2_t cvt = vreinterpretq_u64_u8(x);
-    const uint64_t l1 = vgetq_lane_u64(cvt, 0);
-    return (l1 == 0) && (l1 == vgetq_lane_u64(cvt, 1));
-#endif
-}
-
-#if defined (SK_CPU_BENDIAN)
-static inline uint64x2_t fix_endianness(uint64x2_t x) {
-    return x;
-}
-#else
-static inline uint64x2_t fix_endianness(uint64x2_t x) {
-    return vreinterpretq_u64_u8(vrev64q_u8(vreinterpretq_u8_u64(x)));
-}
-#endif
-
-static void compress_r11eac_blocks(uint64_t* dst, const uint8_t* src, int rowBytes) {
-
-    // Try to avoid switching between vector and non-vector ops...
-    const uint8_t *const src1 = src;
-    const uint8_t *const src2 = src + rowBytes;
-    const uint8_t *const src3 = src + 2*rowBytes;
-    const uint8_t *const src4 = src + 3*rowBytes;
-    uint64_t *const dst1 = dst;
-    uint64_t *const dst2 = dst + 2;
-
-    const uint8x16_t alphaRow1 = vld1q_u8(src1);
-    const uint8x16_t alphaRow2 = vld1q_u8(src2);
-    const uint8x16_t alphaRow3 = vld1q_u8(src3);
-    const uint8x16_t alphaRow4 = vld1q_u8(src4);
-
-    const uint8x16_t cmp12 = vceqq_u8(alphaRow1, alphaRow2);
-    const uint8x16_t cmp34 = vceqq_u8(alphaRow3, alphaRow4);
-    const uint8x16_t cmp13 = vceqq_u8(alphaRow1, alphaRow3);
-
-    const uint8x16_t cmp = vandq_u8(vandq_u8(cmp12, cmp34), cmp13);
-    const uint8x16_t ncmp = vmvnq_u8(cmp);
-    const uint8x16_t nAlphaRow1 = vmvnq_u8(alphaRow1);
-    if (is_zero(ncmp)) {
-        if (is_zero(alphaRow1)) {
-            static const uint64x2_t kTransparent = { 0x0020000000002000ULL,
-                                                     0x0020000000002000ULL };
-            vst1q_u64(dst1, kTransparent);
-            vst1q_u64(dst2, kTransparent);
-            return;
-        } else if (is_zero(nAlphaRow1)) {
-            vst1q_u64(dst1, vreinterpretq_u64_u8(cmp));
-            vst1q_u64(dst2, vreinterpretq_u64_u8(cmp));
-            return;
-        }
-    }
-
-    const uint8x16_t indexRow1 = convert_indices(make_index_row(alphaRow1));
-    const uint8x16_t indexRow2 = convert_indices(make_index_row(alphaRow2));
-    const uint8x16_t indexRow3 = convert_indices(make_index_row(alphaRow3));
-    const uint8x16_t indexRow4 = convert_indices(make_index_row(alphaRow4));
-
-    const uint64x2_t indexRow12 = vreinterpretq_u64_u8(
-        vorrq_u8(vshlq_n_u8(indexRow1, 3), indexRow2));
-    const uint64x2_t indexRow34 = vreinterpretq_u64_u8(
-        vorrq_u8(vshlq_n_u8(indexRow3, 3), indexRow4));
-
-    const uint32x4x2_t blockIndices = vtrnq_u32(vreinterpretq_u32_u64(indexRow12),
-                                                vreinterpretq_u32_u64(indexRow34));
-    const uint64x2_t blockIndicesLeft = vreinterpretq_u64_u32(vrev64q_u32(blockIndices.val[0]));
-    const uint64x2_t blockIndicesRight = vreinterpretq_u64_u32(vrev64q_u32(blockIndices.val[1]));
-
-    const uint64x2_t indicesLeft = fix_endianness(pack_indices(blockIndicesLeft));
-    const uint64x2_t indicesRight = fix_endianness(pack_indices(blockIndicesRight));
-
-    const uint64x2_t d1 = vcombine_u64(vget_low_u64(indicesLeft), vget_low_u64(indicesRight));
-    const uint64x2_t d2 = vcombine_u64(vget_high_u64(indicesLeft), vget_high_u64(indicesRight));
-    vst1q_u64(dst1, d1);
-    vst1q_u64(dst2, d2);
-}
-
-static bool compress_a8_to_r11eac(uint8_t* dst, const uint8_t* src,
-                                  int width, int height, int rowBytes) {
-
-    // Since we're going to operate on 4 blocks at a time, the src width
-    // must be a multiple of 16. However, the height only needs to be a
-    // multiple of 4
-    if (0 == width || 0 == height || (width % 16) != 0 || (height % 4) != 0) {
-        return SkTextureCompressor::CompressBufferToFormat(
-            dst, src,
-            kAlpha_8_SkColorType,
-            width, height, rowBytes,
-            SkTextureCompressor::kR11_EAC_Format, false);
-    }
-
-    const int blocksX = width >> 2;
-    const int blocksY = height >> 2;
-
-    SkASSERT((blocksX % 4) == 0);
-
-    uint64_t* encPtr = reinterpret_cast<uint64_t*>(dst);
-    for (int y = 0; y < blocksY; ++y) {
-        for (int x = 0; x < blocksX; x+=4) {
-            // Compress it
-            compress_r11eac_blocks(encPtr, src + 4*x, rowBytes);
-            encPtr += 4;
-        }
-        src += 4 * rowBytes;
-    }
-    return true;
-}
-
-SkTextureCompressor::CompressionProc
-SkTextureCompressorGetPlatformProc(SkColorType colorType, SkTextureCompressor::Format fmt) {
-    switch (colorType) {
-        case kAlpha_8_SkColorType:
-        {
-            switch (fmt) {
-                case SkTextureCompressor::kR11_EAC_Format:
-                    return compress_a8_to_r11eac;
-                default:
-                    return NULL;
-            }
-        }
-        break;
-
-        default:
-            return NULL;
-    }
-}