Revert of SSE4 opaque blend using intrinsics instead of assembly.

src/opts/SkBlitRow_opts_SSE4_x64_asm.S

Index: src/opts/SkBlitRow_opts_SSE4_x64_asm.S
diff --git a/src/opts/SkBlitRow_opts_SSE4_x64_asm.S b/src/opts/SkBlitRow_opts_SSE4_x64_asm.S
new file mode 100644
index 0000000000000000000000000000000000000000..9a754a635bd7794b72224e9c0be649e01bc91883
--- /dev/null
+++ b/src/opts/SkBlitRow_opts_SSE4_x64_asm.S
@@ -0,0 +1,472 @@
+/*
+ * Copyright 2014 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifdef CRBUG_399842_FIXED
+
+#if defined(__clang__) || (defined(__GNUC__) && !defined(SK_BUILD_FOR_MAC))
+
+#define EXTRACT_ALPHA(var1, var2) \
+    movdqa      %var1, %var2;           /* Clone source pixels to extract alpha */\
+    psrlw       $8, %var2;              /* Discard red and blue, leaving alpha and green */\
+    pshufhw     $0xF5, %var2, %var2;    /* Repeat alpha for scaling (high) */\
+    movdqa      %xmm6, %xmm4;           \
+    pshuflw     $0xF5, %var2, %var2;    /* Repeat alpha for scaling (low) */\
+    movdqa      %xmm5, %xmm3;           \
+    psubw       %var2, %xmm4            /* Finalize alpha calculations */
+
+#define SCALE_PIXELS \
+    psllw       $8, %xmm5;              /* Filter out red and blue components */\
+    pmulhuw     %xmm4, %xmm5;           /* Scale red and blue */\
+    psrlw       $8, %xmm3;              /* Filter out alpha and green components */\
+    pmullw      %xmm4, %xmm3            /* Scale alpha and green */
+
+
+/*
+ * void S32A_Opaque_BlitRow32_SSE4(SkPMColor* SK_RESTRICT dst,
+ *                                 const SkPMColor* SK_RESTRICT src,
+ *                                 int count, U8CPU alpha)
+ *
+ * This function is divided into six blocks: initialization, blit 4-15 pixels,
+ * blit 0-3 pixels, align destination for 16+ pixel blits,
+ * blit 16+ pixels with source unaligned, blit 16+ pixels with source aligned.
+ * There are some code reuse between the blocks.
+ *
+ * The primary optimization comes from checking the source pixels' alpha value.
+ * If the alpha is zero, the pixel can be skipped entirely.
+ * If the alpha is fully opaque, the pixel can be copied directly to the destination.
+ * According to collected statistics, these two cases are the most common.
+ * The main loop(s) uses pre-loading and unrolling in an attempt to reduce the
+ * memory latency worse-case.
+ */
+
+#ifdef __clang__
+    .text
+#else
+    .section .text.sse4.2,"ax",@progbits
+    .type S32A_Opaque_BlitRow32_SSE4_asm, @function
+#endif
+    .p2align 4
+#if defined(SK_BUILD_FOR_MAC)
+    .global _S32A_Opaque_BlitRow32_SSE4_asm
+    .private_extern _S32A_Opaque_BlitRow32_SSE4_asm
+_S32A_Opaque_BlitRow32_SSE4_asm:
+#else
+    .global S32A_Opaque_BlitRow32_SSE4_asm
+    .hidden S32A_Opaque_BlitRow32_SSE4_asm
+S32A_Opaque_BlitRow32_SSE4_asm:
+#endif
+    .cfi_startproc
+    prefetcht0  (%rsi)
+    movl        %edx, %ecx              // Pixel count
+    movq        %rdi, %rdx              // Destination pointer
+    movq        %rsi, %rax              // Source pointer
+
+    // Setup SSE constants
+    movdqa      .LAlphaCheckMask(%rip), %xmm7  // 0xFF000000 mask to check alpha
+    movdqa      .LInverseAlphaCalc(%rip), %xmm6// 16-bit 256 to calculate inv. alpha
+    movdqa      .LResultMergeMask(%rip), %xmm0 // 0x00FF00FF mask (Must be in xmm0 because of pblendvb)
+
+    subl        $4, %ecx                // Check if we have only 0-3 pixels
+    js          .LReallySmall
+    cmpl        $11, %ecx               // Do we have enough pixels to run the main loop?
+    ja          .LBigBlit
+
+    // Handle small blits (4-15 pixels)
+    ////////////////////////////////////////////////////////////////////////////////
+    xorq        %rdi, %rdi              // Reset offset to zero
+
+.LSmallLoop:
+    lddqu       (%rax, %rdi), %xmm1     // Load four source pixels
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LSmallAlphaNotOpaqueOrZero
+    jz          .LSmallAlphaZero
+    movdqu      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+.LSmallAlphaZero:
+    addq        $16, %rdi
+    subl        $4, %ecx                // Check if there are four additional pixels, at least
+    jns         .LSmallLoop
+    jmp         .LSmallRemaining
+
+    // Handle mixed alphas (calculate and scale)
+    .p2align 4
+.LSmallAlphaNotOpaqueOrZero:
+    lddqu       (%rdx, %rdi), %xmm5     // Load four destination pixels
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    addq        $16, %rdi
+    subl        $4, %ecx                // Check if there are four additional pixels, at least
+    pblendvb    %xmm5, %xmm3            // Mask in %xmm0, implicitly
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+    movdqu      %xmm1, -16(%rdx, %rdi)  // Store four destination pixels
+    jns         .LSmallLoop
+
+    // Handle the last 0-3 pixels (also used by the main loops)
+.LSmallRemaining:
+    cmpl        $-4, %ecx               // Check if we are done
+    je          .LSmallExit
+    sall        $2, %ecx                // Calculate offset for last pixels
+    movslq      %ecx, %rcx
+    addq        %rcx, %rdi
+
+    lddqu       (%rax, %rdi), %xmm1     // Load last four source pixels (overlapping)
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    jc          .LSmallRemainingStoreAll// If all alphas are opaque, just store (overlapping)
+    jz          .LSmallExit             // If all alphas are zero, skip the pixels completely
+
+    // Handle mixed alphas (calculate and scale)
+    lddqu       (%rdx, %rdi), %xmm5     // Load last four destination pixels (overlapping)
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+
+    psllw       $8, %xmm3               // Filter out red and blue components
+    pmulhuw     %xmm4, %xmm3            // Scale red and blue
+    movdqa      %xmm5, %xmm2
+    psrlw       $8, %xmm2               // Filter out alpha and green components
+    pmullw      %xmm4, %xmm2            // Scale alpha and green
+
+    cmpl        $-8, %ecx               // Check how many pixels should be written
+    pblendvb    %xmm3, %xmm2            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm2, %xmm1            // Add source and destination pixels together
+    jb          .LSmallPixelsLeft1
+    ja          .LSmallPixelsLeft3      // To avoid double-blending the overlapping pixels...
+    pblendw     $0xF0, %xmm1, %xmm5     // Merge only the final two pixels to the destination
+    movdqu      %xmm5, (%rdx, %rdi)     // Store last two destination pixels
+.LSmallExit:
+    ret
+
+.LSmallPixelsLeft1:
+    pblendw     $0xC0, %xmm1, %xmm5     // Merge only the final pixel to the destination
+    movdqu      %xmm5, (%rdx, %rdi)     // Store last destination pixel
+    ret
+
+.LSmallPixelsLeft3:
+    pblendw     $0xFC, %xmm1, %xmm5     // Merge only the final three pixels to the destination
+    movdqu      %xmm5, (%rdx, %rdi)     // Store last three destination pixels
+    ret
+
+.LSmallRemainingStoreAll:
+    movdqu      %xmm1, (%rdx, %rdi)     // Store last destination pixels (overwrite)
+    ret
+
+    // Handle really small blits (0-3 pixels)
+    ////////////////////////////////////////////////////////////////////////////////
+.LReallySmall:
+    addl        $4, %ecx
+    jle         .LReallySmallExit
+    pcmpeqd     %xmm1, %xmm1
+    cmpl        $2, %ecx                // Check how many pixels should be read
+    pinsrd      $0x0, (%rax), %xmm1     // Load one source pixel
+    pinsrd      $0x0, (%rdx), %xmm5     // Load one destination pixel
+    jb          .LReallySmallCalc
+    pinsrd      $0x1, 4(%rax), %xmm1    // Load second source pixel
+    pinsrd      $0x1, 4(%rdx), %xmm5    // Load second destination pixel
+    je          .LReallySmallCalc
+    pinsrd      $0x2, 8(%rax), %xmm1    // Load third source pixel
+    pinsrd      $0x2, 8(%rdx), %xmm5    // Load third destination pixel
+
+.LReallySmallCalc:
+    ptest       %xmm7, %xmm1            // Check if all alphas are opaque
+    jc          .LReallySmallStore      // If all alphas are opaque, just store
+
+    // Handle mixed alphas (calculate and scale)
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+
+    pand        %xmm0, %xmm5            // Filter out red and blue components
+    pmullw      %xmm4, %xmm5            // Scale red and blue
+    psrlw       $8, %xmm3               // Filter out alpha and green components
+    pmullw      %xmm4, %xmm3            // Scale alpha and green
+
+    psrlw       $8, %xmm5               // Combine results
+    pblendvb    %xmm5, %xmm3            // Mask in %xmm0, implicitly
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+
+.LReallySmallStore:
+    cmpl        $2, %ecx                // Check how many pixels should be written
+    pextrd      $0x0, %xmm1, (%rdx)     // Store one destination pixel
+    jb          .LReallySmallExit
+    pextrd      $0x1, %xmm1, 4(%rdx)    // Store second destination pixel
+    je          .LReallySmallExit
+    pextrd      $0x2, %xmm1, 8(%rdx)    // Store third destination pixel
+.LReallySmallExit:
+    ret
+
+    // Handle bigger blit operations (16+ pixels)
+    ////////////////////////////////////////////////////////////////////////////////
+    .p2align 4
+.LBigBlit:
+    // Align destination?
+    testl       $0xF, %edx
+    lddqu       (%rax), %xmm1           // Pre-load four source pixels
+    jz          .LAligned
+
+    movq        %rdx, %rdi              // Calculate alignment of destination pointer
+    negq        %rdi
+    andl        $0xF, %edi
+
+    // Handle 1-3 pixels to align destination
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    jz          .LAlignDone             // If all alphas are zero, just skip
+    lddqu       (%rdx), %xmm5           // Load four destination pixels
+    jc          .LAlignStore            // If all alphas are opaque, just store
+
+    // Handle mixed alphas (calculate and scale)
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+
+    psllw       $8, %xmm3               // Filter out red and blue components
+    pmulhuw     %xmm4, %xmm3            // Scale red and blue
+    movdqa      %xmm5, %xmm2
+    psrlw       $8, %xmm2               // Filter out alpha and green components
+    pmullw      %xmm4, %xmm2            // Scale alpha and green
+
+    pblendvb    %xmm3, %xmm2            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm2, %xmm1            // Add source and destination pixels together
+
+.LAlignStore:
+    cmpl        $8, %edi                // Check how many pixels should be written
+    jb          .LAlignPixelsLeft1
+    ja          .LAlignPixelsLeft3
+    pblendw     $0x0F, %xmm1, %xmm5     // Blend two pixels
+    jmp .LAlignStorePixels
+
+.LAlignPixelsLeft1:
+    pblendw     $0x03, %xmm1, %xmm5     // Blend one pixel
+    jmp .LAlignStorePixels
+
+.LAlignPixelsLeft3:
+    pblendw     $0x3F, %xmm1, %xmm5     // Blend three pixels
+
+.LAlignStorePixels:
+    movdqu      %xmm5, (%rdx)           // Store destination pixels
+
+.LAlignDone:
+    addq        %rdi, %rax              // Adjust pointers and pixel count
+    addq        %rdi, %rdx
+    shrq        $2, %rdi
+    lddqu       (%rax), %xmm1           // Pre-load new source pixels (after alignment)
+    subl        %edi, %ecx
+
+.LAligned:                              // Destination is guaranteed to be 16 byte aligned
+    xorq        %rdi, %rdi              // Reset offset to zero
+    subl        $8, %ecx                // Decrease counter (Reserve four pixels for the cleanup)
+    testl       $0xF, %eax              // Check alignment of source pointer
+    jz          .LAlignedLoop
+
+    // Source not aligned to destination
+    ////////////////////////////////////////////////////////////////////////////////
+    .p2align 4
+.LUnalignedLoop:                        // Main loop for unaligned, handles eight pixels per iteration
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero00
+    lddqu       16(%rax, %rdi), %xmm2   // Pre-load four source pixels
+    jz          .LAlphaZero00
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+
+.LAlphaZero00:
+    ptest       %xmm7, %xmm2            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero01
+    lddqu       32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+    jz          .LAlphaZero01
+    movdqa      %xmm2, 16(%rdx, %rdi)   // Store four destination pixels
+
+.LAlphaZero01:
+    addq        $32, %rdi               // Adjust offset and pixel count
+    subl        $8, %ecx
+    jae         .LUnalignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+    jmp         .LLoopCleanup0
+
+    .p2align 4
+.LAlphaNotOpaqueOrZero00:
+    movdqa      (%rdx, %rdi), %xmm5     // Load four destination pixels
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    lddqu       16(%rax, %rdi), %xmm2   // Pre-load four source pixels
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+
+    // Handle next four pixels
+    ptest       %xmm7, %xmm2            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero01
+    lddqu       32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+    jz          .LAlphaZero02
+    movdqa      %xmm2, 16(%rdx, %rdi)   // Store four destination pixels
+.LAlphaZero02:
+    addq        $32, %rdi               // Adjust offset and pixel count
+    subl        $8, %ecx
+    jae         .LUnalignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+    jmp         .LLoopCleanup0
+
+    .p2align 4
+.LAlphaNotOpaqueOrZero01:
+    movdqa      16(%rdx, %rdi), %xmm5   // Load four destination pixels
+    EXTRACT_ALPHA(xmm2, xmm1)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    lddqu       32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+    addq        $32, %rdi
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm2            // Add source and destination pixels together
+    subl        $8, %ecx
+    movdqa      %xmm2, -16(%rdx, %rdi)  // Store four destination pixels
+    jae         .LUnalignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+
+    // Cleanup - handle pending pixels from loop
+.LLoopCleanup0:
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero02
+    jz          .LAlphaZero03
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+.LAlphaZero03:
+    addq        $16, %rdi
+    subl        $4, %ecx
+    js          .LSmallRemaining        // Reuse code from small loop
+
+.LRemain0:
+    lddqu       (%rax, %rdi), %xmm1     // Load four source pixels
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero02
+    jz          .LAlphaZero04
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+.LAlphaZero04:
+    addq        $16, %rdi
+    subl        $4, %ecx
+    jmp         .LSmallRemaining        // Reuse code from small loop
+
+.LAlphaNotOpaqueOrZero02:
+    movdqa      (%rdx, %rdi), %xmm5     // Load four destination pixels
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    addq        $16, %rdi
+    subl        $4, %ecx
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+    movdqa      %xmm1, -16(%rdx, %rdi)  // Store four destination pixels
+    js          .LSmallRemaining        // Reuse code from small loop
+    jmp         .LRemain0
+
+    // Source aligned to destination
+    ////////////////////////////////////////////////////////////////////////////////
+    .p2align 4
+.LAlignedLoop:                          // Main loop for aligned, handles eight pixels per iteration
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero10
+    movdqa      16(%rax, %rdi), %xmm2   // Pre-load four source pixels
+    jz          .LAlphaZero10
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+
+.LAlphaZero10:
+    ptest       %xmm7, %xmm2            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero11
+    movdqa      32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+    jz          .LAlphaZero11
+    movdqa      %xmm2, 16(%rdx, %rdi)   // Store four destination pixels
+
+.LAlphaZero11:
+    addq        $32, %rdi               // Adjust offset and pixel count
+    subl        $8, %ecx
+    jae         .LAlignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+    jmp         .LLoopCleanup1
+
+    .p2align 4
+.LAlphaNotOpaqueOrZero10:
+    movdqa      (%rdx, %rdi), %xmm5     // Load four destination pixels
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    movdqa      16(%rax, %rdi), %xmm2   // Pre-load four source pixels
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+
+    // Handle next four pixels
+    ptest       %xmm7, %xmm2            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero11
+    movdqa      32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+    jz          .LAlphaZero12
+    movdqa      %xmm2, 16(%rdx, %rdi)   // Store four destination pixels
+.LAlphaZero12:
+    addq        $32, %rdi               // Adjust offset and pixel count
+    subl        $8, %ecx
+    jae         .LAlignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+    jmp         .LLoopCleanup1
+
+    .p2align 4
+.LAlphaNotOpaqueOrZero11:
+    movdqa      16(%rdx, %rdi), %xmm5   // Load four destination pixels
+    EXTRACT_ALPHA(xmm2, xmm1)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+    movdqa      32(%rax, %rdi), %xmm1   // Pre-load four source pixels
+
+    addq        $32, %rdi
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm2            // Add source and destination pixels together
+    subl        $8, %ecx
+    movdqa      %xmm2, -16(%rdx, %rdi)  // Store four destination pixels
+    jae         .LAlignedLoop
+    addl        $8, %ecx                // Adjust pixel count
+
+    // Cleanup - handle four pending pixels from loop
+.LLoopCleanup1:
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero12
+    jz          .LAlphaZero13
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+.LAlphaZero13:
+    addq        $16, %rdi
+    subl        $4, %ecx
+    js          .LSmallRemaining        // Reuse code from small loop
+
+.LRemain1:
+    movdqa      (%rax, %rdi), %xmm1     // Pre-load four source pixels
+    ptest       %xmm7, %xmm1            // Check if all alphas are zero or opaque
+    ja          .LAlphaNotOpaqueOrZero12
+    jz          .LAlphaZero14
+    movdqa      %xmm1, (%rdx, %rdi)     // Store four destination pixels
+.LAlphaZero14:
+    addq        $16, %rdi
+    subl        $4, %ecx
+    jmp         .LSmallRemaining        // Reuse code from small loop
+
+.LAlphaNotOpaqueOrZero12:
+    movdqa      (%rdx, %rdi), %xmm5     // Load four destination pixels
+    EXTRACT_ALPHA(xmm1, xmm2)           // Extract and clone alpha value
+    SCALE_PIXELS                        // Scale pixels using alpha
+
+    addq        $16, %rdi
+    subl        $4, %ecx
+    pblendvb    %xmm5, %xmm3            // Combine results (mask in %xmm0, implicitly)
+    paddb       %xmm3, %xmm1            // Add source and destination pixels together
+    movdqa      %xmm1, -16(%rdx, %rdi)  // Store four destination pixels
+    js          .LSmallRemaining        // Reuse code from small loop
+    jmp         .LRemain1
+
+    .cfi_endproc
+#ifndef __clang__
+    .size S32A_Opaque_BlitRow32_SSE4_asm, .-S32A_Opaque_BlitRow32_SSE4_asm
+#endif
+
+    // Constants for SSE code
+#ifndef __clang__
+    .section .rodata
+#endif
+    .p2align 4
+.LAlphaCheckMask:
+    .long   0xFF000000, 0xFF000000, 0xFF000000, 0xFF000000
+.LInverseAlphaCalc:
+    .word   256, 256, 256, 256, 256, 256, 256, 256
+.LResultMergeMask:
+    .long   0x00FF00FF, 0x00FF00FF, 0x00FF00FF, 0x00FF00FF
+#endif
+
+#endif // CRBUG_399842_FIXED