src/libANGLE/PixelLocalStorage.cpp

//
// Copyright 2022 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// PixelLocalStorage.cpp: Defines the renderer-agnostic container classes
// gl::PixelLocalStorage and gl::PixelLocalStoragePlane for
// ANGLE_shader_pixel_local_storage.

#include "libANGLE/PixelLocalStorage.h"

#include <numeric>
#include "libANGLE/Context.h"
#include "libANGLE/Framebuffer.h"
#include "libANGLE/Texture.h"
#include "libANGLE/renderer/ContextImpl.h"

namespace gl
{
// RAII utilities for working with GL state.
namespace
{
class ScopedBindTexture2D : angle::NonCopyable
{
  public:
    ScopedBindTexture2D(Context *context, TextureID texture)
        : mContext(context),
          mSavedTexBinding2D(
              mContext->getState().getSamplerTextureId(mContext->getState().getActiveSampler(),
                                                       TextureType::_2D))
    {
        mContext->bindTexture(TextureType::_2D, texture);
    }

    ~ScopedBindTexture2D() { mContext->bindTexture(TextureType::_2D, mSavedTexBinding2D); }

  private:
    Context *const mContext;
    TextureID mSavedTexBinding2D;
};

class ScopedRestoreDrawFramebuffer : angle::NonCopyable
{
  public:
    ScopedRestoreDrawFramebuffer(Context *context)
        : mContext(context), mSavedFramebuffer(mContext->getState().getDrawFramebuffer())
    {
        ASSERT(mSavedFramebuffer);
    }

    ~ScopedRestoreDrawFramebuffer() { mContext->bindDrawFramebuffer(mSavedFramebuffer->id()); }

  private:
    Context *const mContext;
    Framebuffer *const mSavedFramebuffer;
};

class ScopedDisableScissor : angle::NonCopyable
{
  public:
    ScopedDisableScissor(Context *context)
        : mContext(context), mScissorTestEnabled(mContext->getState().isScissorTestEnabled())
    {
        if (mScissorTestEnabled)
        {
            mContext->disable(GL_SCISSOR_TEST);
        }
    }

    ~ScopedDisableScissor()
    {
        if (mScissorTestEnabled)
        {
            mContext->enable(GL_SCISSOR_TEST);
        }
    }

  private:
    Context *const mContext;
    const GLint mScissorTestEnabled;
};

class ScopedEnableColorMask : angle::NonCopyable
{
  public:
    ScopedEnableColorMask(Context *context, int numDrawBuffers)
        : mContext(context), mNumDrawBuffers(numDrawBuffers)
    {
        const State &state = mContext->getState();
        if (!mContext->getExtensions().drawBuffersIndexedAny())
        {
            std::array<bool, 4> &mask = mSavedColorMasks[0];
            state.getBlendStateExt().getColorMaskIndexed(0, &mask[0], &mask[1], &mask[2], &mask[3]);
            mContext->colorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
        }
        else
        {
            for (int i = 0; i < mNumDrawBuffers; ++i)
            {
                std::array<bool, 4> &mask = mSavedColorMasks[i];
                state.getBlendStateExt().getColorMaskIndexed(i, &mask[0], &mask[1], &mask[2],
                                                             &mask[3]);
                mContext->colorMaski(i, GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
            }
        }
    }

    ~ScopedEnableColorMask()
    {
        if (!mContext->getExtensions().drawBuffersIndexedAny())
        {
            const std::array<bool, 4> &mask = mSavedColorMasks[0];
            mContext->colorMask(mask[0], mask[1], mask[2], mask[3]);
        }
        else
        {
            for (int i = 0; i < mNumDrawBuffers; ++i)
            {
                const std::array<bool, 4> &mask = mSavedColorMasks[i];
                mContext->colorMaski(i, mask[0], mask[1], mask[2], mask[3]);
            }
        }
    }

  private:
    Context *const mContext;
    const int mNumDrawBuffers;
    DrawBuffersArray<std::array<bool, 4>> mSavedColorMasks;
};
}  // namespace

PixelLocalStoragePlane::~PixelLocalStoragePlane()
{
    // Call deinitialize or onContextObjectsLost first!
    ASSERT(mMemorylessTextureID.value == 0);
    // Call deinitialize or onFramebufferDestroyed first!
    ASSERT(mTextureRef == nullptr);
}

void PixelLocalStoragePlane::onContextObjectsLost()
{
    // We normally call deleteTexture on the memoryless plane texture ID, since we own it, but in
    // this case we can let it go.
    mMemorylessTextureID = TextureID();
}

void PixelLocalStoragePlane::onFramebufferDestroyed(const Context *context)
{
    if (mTextureRef != nullptr)
    {
        mTextureRef->release(context);
        mTextureRef = nullptr;
    }
}

void PixelLocalStoragePlane::deinitialize(Context *context)
{
    mInternalformat = GL_NONE;
    mMemoryless     = false;
    if (mMemorylessTextureID.value != 0)
    {
        // The app could have technically deleted mMemorylessTextureID by guessing its value and
        // calling glDeleteTextures, but it seems unnecessary to worry about that here. (Worst case
        // we delete one of their textures.) This also isn't a problem in WebGL.
        context->deleteTexture(mMemorylessTextureID);
        mMemorylessTextureID = TextureID();
    }
    if (mTextureRef != nullptr)
    {
        mTextureRef->release(context);
        mTextureRef = nullptr;
    }
}

void PixelLocalStoragePlane::setMemoryless(Context *context, GLenum internalformat)
{
    deinitialize(context);
    mInternalformat    = internalformat;
    mMemoryless        = true;
    mTextureImageIndex = ImageIndex::MakeFromType(TextureType::_2D, 0, 0);
    // The backing texture will get allocated lazily, once we know what dimensions it should be.
    ASSERT(mMemorylessTextureID.value == 0);
    ASSERT(mTextureRef == nullptr);
}

void PixelLocalStoragePlane::setTextureBacked(Context *context, Texture *tex, int level, int layer)
{
    deinitialize(context);
    ASSERT(tex->getImmutableFormat());
    mInternalformat    = tex->getState().getBaseLevelDesc().format.info->internalFormat;
    mMemoryless        = false;
    mTextureImageIndex = ImageIndex::MakeFromType(tex->getType(), level, layer);
    mTextureRef        = tex;
    mTextureRef->addRef();
}

bool PixelLocalStoragePlane::isTextureIDDeleted(const Context *context) const
{
    // We can tell if the texture has been deleted by looking up mTextureRef's ID on the Context. If
    // they don't match, it's been deleted.
    ASSERT(!isDeinitialized() || mTextureRef == nullptr);
    return mTextureRef != nullptr && context->getTexture(mTextureRef->id()) != mTextureRef;
}

GLint PixelLocalStoragePlane::getIntegeri(const Context *context, GLenum target) const
{
    if (!isDeinitialized())
    {
        bool memoryless = isMemoryless() || isTextureIDDeleted(context);
        switch (target)
        {
            case GL_PIXEL_LOCAL_FORMAT_ANGLE:
                return mInternalformat;
            case GL_PIXEL_LOCAL_TEXTURE_NAME_ANGLE:
                return memoryless ? 0 : mTextureRef->id().value;
            case GL_PIXEL_LOCAL_TEXTURE_LEVEL_ANGLE:
                return memoryless ? 0 : mTextureImageIndex.getLevelIndex();
            case GL_PIXEL_LOCAL_TEXTURE_LAYER_ANGLE:
                return memoryless ? 0 : mTextureImageIndex.getLayerIndex();
        }
    }
    // Since GL_NONE == 0, PLS queries all return 0 when the plane is deinitialized.
    static_assert(GL_NONE == 0, "Expecting GL_NONE to be zero.");
    return 0;
}

bool PixelLocalStoragePlane::getTextureImageExtents(const Context *context, Extents *extents) const
{
    if (isDeinitialized() || isMemoryless() || isTextureIDDeleted(context))
    {
        return false;
    }
    ASSERT(mTextureRef != nullptr);
    *extents =
        mTextureRef->getExtents(mTextureImageIndex.getTarget(), mTextureImageIndex.getLevelIndex());
    extents->depth = 0;
    return true;
}

void PixelLocalStoragePlane::ensureBackingTextureIfMemoryless(Context *context, Extents plsExtents)
{
    ASSERT(!isDeinitialized());
    ASSERT(!isTextureIDDeleted(context));  // Convert to memoryless first in this case.
    if (!isMemoryless())
    {
        ASSERT(mTextureRef != nullptr);
        return;
    }

    // Internal textures backing memoryless planes are always 2D and not mipmapped.
    ASSERT(mTextureImageIndex.getType() == TextureType::_2D);
    ASSERT(mTextureImageIndex.getLevelIndex() == 0);
    ASSERT(mTextureImageIndex.getLayerIndex() == 0);
    const bool hasMemorylessTextureId = mMemorylessTextureID.value != 0;
    const bool hasTextureRef          = mTextureRef != nullptr;
    ASSERT(hasMemorylessTextureId == hasTextureRef);

    // Do we need to allocate a new backing texture?
    if (mTextureRef == nullptr ||
        static_cast<GLsizei>(mTextureRef->getWidth(TextureTarget::_2D, 0)) != plsExtents.width ||
        static_cast<GLsizei>(mTextureRef->getHeight(TextureTarget::_2D, 0)) != plsExtents.height)
    {
        // Call setMemoryless() to release our current data.
        setMemoryless(context, mInternalformat);
        ASSERT(mTextureRef == nullptr);
        ASSERT(mMemorylessTextureID.value == 0);

        // Create a new texture that backs the memoryless plane.
        mMemorylessTextureID = context->createTexture();
        {
            ScopedBindTexture2D scopedBindTexture2D(context, mMemorylessTextureID);
            context->bindTexture(TextureType::_2D, mMemorylessTextureID);
            context->texStorage2D(TextureType::_2D, 1, mInternalformat, plsExtents.width,
                                  plsExtents.height);
        }

        mTextureRef = context->getTexture(mMemorylessTextureID);
        ASSERT(mTextureRef != nullptr);
        ASSERT(mTextureRef->id() == mMemorylessTextureID);
        mTextureRef->addRef();
    }
}

void PixelLocalStoragePlane::attachToDrawFramebuffer(Context *context, GLenum colorAttachment) const
{
    ASSERT(!isDeinitialized());
    ASSERT(mTextureRef != nullptr);      // Call ensureBackingTextureIfMemoryless() first!
    if (mTextureImageIndex.usesTex3D())  // GL_TEXTURE_3D or GL_TEXTURE_2D_ARRAY.
    {
        context->framebufferTextureLayer(GL_DRAW_FRAMEBUFFER, colorAttachment, mTextureRef->id(),
                                         mTextureImageIndex.getLevelIndex(),
                                         mTextureImageIndex.getLayerIndex());
    }
    else
    {
        context->framebufferTexture2D(GL_DRAW_FRAMEBUFFER, colorAttachment,
                                      mTextureImageIndex.getTarget(), mTextureRef->id(),
                                      mTextureImageIndex.getLevelIndex());
    }
}

// Clears the draw buffer at 0-based index 'drawBufferIdx' on the current framebuffer.
class ClearBufferCommands : public PixelLocalStoragePlane::ClearCommands
{
  public:
    ClearBufferCommands(Context *context) : mContext(context) {}

    void clearfv(int drawBufferIdx, const GLfloat value[]) const override
    {
        mContext->clearBufferfv(GL_COLOR, drawBufferIdx, value);
    }

    void cleariv(int drawBufferIdx, const GLint value[]) const override
    {
        mContext->clearBufferiv(GL_COLOR, drawBufferIdx, value);
    }

    void clearuiv(int drawBufferIdx, const GLuint value[]) const override
    {
        mContext->clearBufferuiv(GL_COLOR, drawBufferIdx, value);
    }

  private:
    Context *const mContext;
};

template <typename T, size_t N>
void ClampArray(std::array<T, N> &arr, T lo, T hi)
{
    for (T &x : arr)
    {
        x = std::clamp(x, lo, hi);
    }
}

void PixelLocalStoragePlane::issueClearCommand(ClearCommands *clearCommands,
                                               int target,
                                               GLenum loadop) const
{
    switch (mInternalformat)
    {
        case GL_RGBA8:
        case GL_R32F:
        {
            std::array<GLfloat, 4> clearValue = {0, 0, 0, 0};
            if (loadop == GL_LOAD_OP_CLEAR_ANGLE)
            {
                clearValue = mClearValuef;
                if (mInternalformat == GL_RGBA8)
                {
                    ClampArray(clearValue, 0.f, 1.f);
                }
            }
            clearCommands->clearfv(target, clearValue.data());
            break;
        }
        case GL_RGBA8I:
        {
            std::array<GLint, 4> clearValue = {0, 0, 0, 0};
            if (loadop == GL_LOAD_OP_CLEAR_ANGLE)
            {
                clearValue = mClearValuei;
                ClampArray(clearValue, -128, 127);
            }
            clearCommands->cleariv(target, clearValue.data());
            break;
        }
        case GL_RGBA8UI:
        case GL_R32UI:
        {
            std::array<GLuint, 4> clearValue = {0, 0, 0, 0};
            if (loadop == GL_LOAD_OP_CLEAR_ANGLE)
            {
                clearValue = mClearValueui;
                if (mInternalformat == GL_RGBA8UI)
                {
                    ClampArray(clearValue, 0u, 255u);
                }
            }
            clearCommands->clearuiv(target, clearValue.data());
            break;
        }
        default:
            // Invalid PLS internalformats should not have made it this far.
            UNREACHABLE();
    }
}

void PixelLocalStoragePlane::bindToImage(Context *context, GLuint unit, bool needsR32Packing) const
{
    ASSERT(!isDeinitialized());
    ASSERT(mTextureRef != nullptr);  // Call ensureBackingTextureIfMemoryless() first!
    GLenum imageBindingFormat = mInternalformat;
    if (needsR32Packing)
    {
        // D3D and ES require us to pack all PLS formats into r32f, r32i, or r32ui images.
        switch (imageBindingFormat)
        {
            case GL_RGBA8:
            case GL_RGBA8UI:
                imageBindingFormat = GL_R32UI;
                break;
            case GL_RGBA8I:
                imageBindingFormat = GL_R32I;
                break;
        }
    }
    if (mTextureRef->getType() != TextureType::_2D)
    {
        // TODO(anglebug.com/7279): Texture types other than GL_TEXTURE_2D will take a lot of
        // consideration to support on all backends. Hold of on fully implementing them until the
        // other backends are in place.
        UNIMPLEMENTED();
    }
    context->bindImageTexture(unit, mTextureRef->id(), mTextureImageIndex.getLevelIndex(), GL_FALSE,
                              mTextureImageIndex.getLayerIndex(), GL_READ_WRITE,
                              imageBindingFormat);
}

const Texture *PixelLocalStoragePlane::getBackingTexture(const Context *context) const
{
    ASSERT(!isDeinitialized());
    ASSERT(!isMemoryless());
    ASSERT(!isTextureIDDeleted(context));  // In this case we are also memoryless.
    return mTextureRef;
}

PixelLocalStorage::PixelLocalStorage(const ShPixelLocalStorageOptions &plsOptions)
    : mPLSOptions(plsOptions)
{}

PixelLocalStorage::~PixelLocalStorage() {}

void PixelLocalStorage::onFramebufferDestroyed(const Context *context)
{
    if (context->getRefCount() == 0)
    {
        // If the Context's refcount is zero, we know it's in a teardown state and we can just let
        // go of our GL objects -- they get cleaned up as part of context teardown. Otherwise, the
        // Context should have called deleteContextObjects before reaching this point.
        onContextObjectsLost();
        for (PixelLocalStoragePlane &plane : mPlanes)
        {
            plane.onContextObjectsLost();
        }
    }
    for (PixelLocalStoragePlane &plane : mPlanes)
    {
        plane.onFramebufferDestroyed(context);
    }
}

void PixelLocalStorage::deleteContextObjects(Context *context)
{
    onDeleteContextObjects(context);
    for (PixelLocalStoragePlane &plane : mPlanes)
    {
        plane.deinitialize(context);
    }
}

void PixelLocalStorage::begin(Context *context, GLsizei n, const GLenum loadops[])
{
    // Convert planes whose backing texture has been deleted to memoryless, and find the pixel local
    // storage rendering dimensions.
    Extents plsExtents;
    bool hasPLSExtents = false;
    for (GLsizei i = 0; i < n; ++i)
    {
        if (loadops[i] == GL_LOAD_OP_DISABLE_ANGLE)
        {
            continue;
        }
        PixelLocalStoragePlane &plane = mPlanes[i];
        if (plane.isTextureIDDeleted(context))
        {
            // [ANGLE_shader_pixel_local_storage] Section 4.4.2.X "Configuring Pixel Local Storage
            // on a Framebuffer": When a texture object is deleted, any pixel local storage plane to
            // which it was bound is automatically converted to a memoryless plane of matching
            // internalformat.
            plane.setMemoryless(context, plane.getInternalformat());
        }
        if (!hasPLSExtents && plane.getTextureImageExtents(context, &plsExtents))
        {
            hasPLSExtents = true;
        }
    }
    if (!hasPLSExtents)
    {
        // All PLS planes are memoryless. Use the rendering area of the framebuffer instead.
        plsExtents =
            context->getState().getDrawFramebuffer()->getState().getAttachmentExtentsIntersection();
        ASSERT(plsExtents.depth == 0);
    }
    for (GLsizei i = 0; i < n; ++i)
    {
        if (loadops[i] == GL_LOAD_OP_DISABLE_ANGLE)
        {
            continue;
        }
        PixelLocalStoragePlane &plane = mPlanes[i];
        if (mPLSOptions.type == ShPixelLocalStorageType::ImageLoadStore ||
            mPLSOptions.type == ShPixelLocalStorageType::FramebufferFetch)
        {
            plane.ensureBackingTextureIfMemoryless(context, plsExtents);
        }
        plane.markActive(true);
    }

    onBegin(context, n, loadops, plsExtents);
}

void PixelLocalStorage::end(Context *context, const GLenum storeops[])
{
    onEnd(context, storeops);

    GLsizei n = context->getState().getPixelLocalStorageActivePlanes();
    for (GLsizei i = 0; i < n; ++i)
    {
        mPlanes[i].markActive(false);
    }
}

void PixelLocalStorage::barrier(Context *context)
{
    ASSERT(!context->getExtensions().shaderPixelLocalStorageCoherentANGLE);
    onBarrier(context);
}

namespace
{
// Implements pixel local storage with image load/store shader operations.
class PixelLocalStorageImageLoadStore : public PixelLocalStorage
{
  public:
    PixelLocalStorageImageLoadStore(const ShPixelLocalStorageOptions &plsOptions)
        : PixelLocalStorage(plsOptions)
    {
        ASSERT(mPLSOptions.type == ShPixelLocalStorageType::ImageLoadStore);
    }

    // Call deleteContextObjects or onContextObjectsLost first!
    ~PixelLocalStorageImageLoadStore() override
    {
        ASSERT(mScratchFramebufferForClearing.value == 0);
    }

    void onContextObjectsLost() override
    {
        mScratchFramebufferForClearing = FramebufferID();  // Let go of GL objects.
    }

    void onDeleteContextObjects(Context *context) override
    {
        if (mScratchFramebufferForClearing.value != 0)
        {
            context->deleteFramebuffer(mScratchFramebufferForClearing);
            mScratchFramebufferForClearing = FramebufferID();
        }
    }

    void onBegin(Context *context, GLsizei n, const GLenum loadops[], Extents plsExtents) override
    {
        // Save the image bindings so we can restore them during onEnd().
        const State &state = context->getState();
        ASSERT(static_cast<size_t>(n) <= state.getImageUnits().size());
        mSavedImageBindings.clear();
        mSavedImageBindings.reserve(n);
        for (GLsizei i = 0; i < n; ++i)
        {
            mSavedImageBindings.emplace_back(state.getImageUnit(i));
        }

        Framebuffer *framebuffer = state.getDrawFramebuffer();
        if (mPLSOptions.renderPassNeedsAMDRasterOrderGroupsWorkaround)
        {
            // anglebug.com/7792 -- Metal [[raster_order_group()]] does not work for read_write
            // textures on AMD when the render pass doesn't have a color attachment on slot 0. To
            // work around this we attach one of the PLS textures to GL_COLOR_ATTACHMENT0, if there
            // isn't one already.
            mHadColorAttachment0 = framebuffer->getColorAttachment(0) != nullptr;
            if (!mHadColorAttachment0)
            {
                // Remember the current draw buffer state so we can restore it during onEnd().
                const DrawBuffersVector<GLenum> &appDrawBuffers =
                    framebuffer->getDrawBufferStates();
                mSavedDrawBuffers.resize(appDrawBuffers.size());
                std::copy(appDrawBuffers.begin(), appDrawBuffers.end(), mSavedDrawBuffers.begin());

                // Turn off draw buffer 0.
                if (mSavedDrawBuffers[0] != GL_NONE)
                {
                    GLenum drawBuffer0   = mSavedDrawBuffers[0];
                    mSavedDrawBuffers[0] = GL_NONE;
                    context->drawBuffers(static_cast<GLsizei>(mSavedDrawBuffers.size()),
                                         mSavedDrawBuffers.data());
                    mSavedDrawBuffers[0] = drawBuffer0;
                }

                // Attach one of the PLS textures to GL_COLOR_ATTACHMENT0.
                for (GLsizei i = 0; i < n; ++i)
                {
                    if (loadops[i] == GL_LOAD_OP_DISABLE_ANGLE)
                    {
                        continue;
                    }
                    getPlane(i).attachToDrawFramebuffer(context, GL_COLOR_ATTACHMENT0);
                    break;
                }
            }
        }
        else
        {
            // Save the default framebuffer width/height so we can restore it during onEnd().
            mSavedFramebufferDefaultWidth  = framebuffer->getDefaultWidth();
            mSavedFramebufferDefaultHeight = framebuffer->getDefaultHeight();

            // Specify the framebuffer width/height explicitly in case we end up rendering
            // exclusively to shader images.
            context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_WIDTH,
                                           plsExtents.width);
            context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_HEIGHT,
                                           plsExtents.height);
        }

        // Guard GL state and bind a scratch framebuffer in case we need to reallocate or clear any
        // PLS planes.
        const size_t maxDrawBuffers = context->getCaps().maxDrawBuffers;
        ScopedRestoreDrawFramebuffer ScopedRestoreDrawFramebuffer(context);
        if (mScratchFramebufferForClearing.value == 0)
        {
            context->genFramebuffers(1, &mScratchFramebufferForClearing);
            context->bindFramebuffer(GL_DRAW_FRAMEBUFFER, mScratchFramebufferForClearing);
            // Turn on all draw buffers on the scratch framebuffer for clearing.
            DrawBuffersVector<GLenum> drawBuffers(maxDrawBuffers);
            std::iota(drawBuffers.begin(), drawBuffers.end(), GL_COLOR_ATTACHMENT0);
            context->drawBuffers(static_cast<int>(drawBuffers.size()), drawBuffers.data());
        }
        else
        {
            context->bindFramebuffer(GL_DRAW_FRAMEBUFFER, mScratchFramebufferForClearing);
        }
        ScopedDisableScissor scopedDisableScissor(context);

        // Bind and clear the PLS planes.
        size_t maxClearedAttachments = 0;
        for (GLsizei i = 0; i < n;)
        {
            DrawBuffersVector<int> pendingClears;
            for (; pendingClears.size() < maxDrawBuffers && i < n; ++i)
            {
                GLenum loadop = loadops[i];
                if (loadop == GL_LOAD_OP_DISABLE_ANGLE)
                {
                    continue;
                }
                const PixelLocalStoragePlane &plane = getPlane(i);
                ASSERT(!plane.isDeinitialized());
                plane.bindToImage(context, i, !mPLSOptions.supportsNativeRGBA8ImageFormats);
                if (loadop == GL_LOAD_OP_ZERO_ANGLE || loadop == GL_LOAD_OP_CLEAR_ANGLE)
                {
                    plane.attachToDrawFramebuffer(
                        context, GL_COLOR_ATTACHMENT0 + static_cast<GLenum>(pendingClears.size()));
                    pendingClears.push_back(i);  // Defer the clear for later.
                }
            }
            // Clear in batches in order to be more efficient with GL state.
            ScopedEnableColorMask scopedEnableColorMask(context,
                                                        static_cast<int>(pendingClears.size()));
            ClearBufferCommands clearBufferCommands(context);
            for (size_t drawBufferIdx = 0; drawBufferIdx < pendingClears.size(); ++drawBufferIdx)
            {
                int plsIdx = pendingClears[drawBufferIdx];
                getPlane(plsIdx).issueClearCommand(
                    &clearBufferCommands, static_cast<int>(drawBufferIdx), loadops[plsIdx]);
            }
            maxClearedAttachments = std::max(maxClearedAttachments, pendingClears.size());
        }

        // Detach the cleared PLS textures from the scratch framebuffer.
        for (size_t i = 0; i < maxClearedAttachments; ++i)
        {
            context->framebufferTexture2D(GL_DRAW_FRAMEBUFFER,
                                          GL_COLOR_ATTACHMENT0 + static_cast<GLenum>(i),
                                          TextureTarget::_2D, TextureID(), 0);
        }

        // Unlike other barriers, GL_SHADER_IMAGE_ACCESS_BARRIER_BIT also synchronizes all types of
        // memory accesses that happened before the barrier:
        //
        //   SHADER_IMAGE_ACCESS_BARRIER_BIT: Memory accesses using shader built-in image load and
        //   store functions issued after the barrier will reflect data written by shaders prior to
        //   the barrier. Additionally, image stores issued after the barrier will not execute until
        //   all memory accesses (e.g., loads, stores, texture fetches, vertex fetches) initiated
        //   prior to the barrier complete.
        //
        // So we don't any barriers other than GL_SHADER_IMAGE_ACCESS_BARRIER_BIT during begin().
        context->memoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
    }

    void onEnd(Context *context, const GLenum storeops[]) override
    {
        GLsizei n = context->getState().getPixelLocalStorageActivePlanes();

        // Restore the image bindings. Since glBindImageTexture and any commands that modify
        // textures are banned while PLS is active, these will all still be alive and valid.
        ASSERT(mSavedImageBindings.size() == static_cast<size_t>(n));
        for (GLuint unit = 0; unit < mSavedImageBindings.size(); ++unit)
        {
            ImageUnit &binding = mSavedImageBindings[unit];
            context->bindImageTexture(unit, binding.texture.id(), binding.level, binding.layered,
                                      binding.layer, binding.access, binding.format);

            // BindingPointers have to be explicitly cleaned up.
            binding.texture.set(context, nullptr);
        }
        mSavedImageBindings.clear();

        if (mPLSOptions.renderPassNeedsAMDRasterOrderGroupsWorkaround)
        {
            if (!mHadColorAttachment0)
            {
                // Detach the PLS texture we attached to GL_COLOR_ATTACHMENT0.
                context->framebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                              TextureTarget::_2D, TextureID(), 0);

                // Restore the draw buffer state from before PLS was enabled.
                if (mSavedDrawBuffers[0] != GL_NONE)
                {
                    context->drawBuffers(static_cast<GLsizei>(mSavedDrawBuffers.size()),
                                         mSavedDrawBuffers.data());
                }
                mSavedDrawBuffers.clear();
            }
        }
        else
        {
            // Restore the default framebuffer width/height.
            context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_WIDTH,
                                           mSavedFramebufferDefaultWidth);
            context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_HEIGHT,
                                           mSavedFramebufferDefaultHeight);
        }

        // We need ALL_BARRIER_BITS during end() because GL_SHADER_IMAGE_ACCESS_BARRIER_BIT doesn't
        // synchronize all types of memory accesses that can happen after the barrier.
        context->memoryBarrier(GL_ALL_BARRIER_BITS);
    }

    void onBarrier(Context *context) override
    {
        context->memoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
    }

  private:
    // D3D and ES require us to pack all PLS formats into r32f, r32i, or r32ui images.
    FramebufferID mScratchFramebufferForClearing{};

    // Saved values to restore during onEnd().
    std::vector<ImageUnit> mSavedImageBindings;
    // If mPLSOptions.plsRenderPassNeedsColorAttachmentWorkaround.
    bool mHadColorAttachment0;
    DrawBuffersVector<GLenum> mSavedDrawBuffers;
    // If !mPLSOptions.plsRenderPassNeedsColorAttachmentWorkaround.
    GLint mSavedFramebufferDefaultWidth;
    GLint mSavedFramebufferDefaultHeight;
};

// Implements pixel local storage via framebuffer fetch.
class PixelLocalStorageFramebufferFetch : public PixelLocalStorage
{
  public:
    PixelLocalStorageFramebufferFetch(const ShPixelLocalStorageOptions &plsOptions)
        : PixelLocalStorage(plsOptions)
    {
        ASSERT(mPLSOptions.type == ShPixelLocalStorageType::FramebufferFetch);
    }

    void onContextObjectsLost() override {}

    void onDeleteContextObjects(Context *) override {}

    void onBegin(Context *context, GLsizei n, const GLenum loadops[], Extents plsExtents) override
    {
        const State &state                              = context->getState();
        const Caps &caps                                = context->getCaps();
        Framebuffer *framebuffer                        = context->getState().getDrawFramebuffer();
        const DrawBuffersVector<GLenum> &appDrawBuffers = framebuffer->getDrawBufferStates();

        // Remember the current draw buffer state so we can restore it during onEnd().
        mSavedDrawBuffers.resize(appDrawBuffers.size());
        std::copy(appDrawBuffers.begin(), appDrawBuffers.end(), mSavedDrawBuffers.begin());

        // Set up new draw buffers for PLS.
        int firstPLSDrawBuffer = caps.maxCombinedDrawBuffersAndPixelLocalStoragePlanes - n;
        int numAppDrawBuffers =
            std::min(static_cast<int>(appDrawBuffers.size()), firstPLSDrawBuffer);
        DrawBuffersArray<GLenum> plsDrawBuffers;
        std::copy(appDrawBuffers.begin(), appDrawBuffers.begin() + numAppDrawBuffers,
                  plsDrawBuffers.begin());
        std::fill(plsDrawBuffers.begin() + numAppDrawBuffers,
                  plsDrawBuffers.begin() + firstPLSDrawBuffer, GL_NONE);

        mBlendsToReEnable.reset();
        mColorMasksToRestore.reset();
        bool needsClear = false;

        bool hasIndexedBlendAndColorMask = context->getExtensions().drawBuffersIndexedAny();
        if (!hasIndexedBlendAndColorMask)
        {
            // We don't have indexed blend and color mask control. Disable them globally. (This also
            // means the app can't have its own draw buffers while PLS is active.)
            ASSERT(caps.maxColorAttachmentsWithActivePixelLocalStorage == 0);
            if (state.isBlendEnabled())
            {
                context->disable(GL_BLEND);
                mBlendsToReEnable.set(0);
            }
            std::array<bool, 4> &mask = mSavedColorMasks[0];
            state.getBlendStateExt().getColorMaskIndexed(0, &mask[0], &mask[1], &mask[2], &mask[3]);
            if (!(mask[0] && mask[1] && mask[2] && mask[3]))
            {
                context->colorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
                mColorMasksToRestore.set(0);
            }
        }

        for (GLsizei i = 0; i < n; ++i)
        {
            GLuint drawBufferIdx = GetDrawBufferIdx(caps, i);
            GLenum loadop        = loadops[i];
            if (loadop == GL_LOAD_OP_DISABLE_ANGLE)
            {
                plsDrawBuffers[drawBufferIdx] = GL_NONE;
                continue;
            }

            const PixelLocalStoragePlane &plane = getPlane(i);
            ASSERT(!plane.isDeinitialized());

            // Attach our PLS texture to the framebuffer. Validation should have already ensured
            // nothing else was attached at this point.
            GLenum colorAttachment = GL_COLOR_ATTACHMENT0 + drawBufferIdx;
            ASSERT(!framebuffer->getAttachment(context, colorAttachment));
            plane.attachToDrawFramebuffer(context, colorAttachment);
            plsDrawBuffers[drawBufferIdx] = colorAttachment;

            if (hasIndexedBlendAndColorMask)
            {
                // Ensure blend and color mask are disabled for this draw buffer.
                if (state.isBlendEnabledIndexed(drawBufferIdx))
                {
                    context->disablei(GL_BLEND, drawBufferIdx);
                    mBlendsToReEnable.set(drawBufferIdx);
                }
                std::array<bool, 4> &mask = mSavedColorMasks[drawBufferIdx];
                state.getBlendStateExt().getColorMaskIndexed(drawBufferIdx, &mask[0], &mask[1],
                                                             &mask[2], &mask[3]);
                if (!(mask[0] && mask[1] && mask[2] && mask[3]))
                {
                    context->colorMaski(drawBufferIdx, GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
                    mColorMasksToRestore.set(drawBufferIdx);
                }
            }

            needsClear = needsClear || (loadop != GL_LOAD_OP_LOAD_ANGLE);
        }

        // Turn on the PLS draw buffers.
        context->drawBuffers(caps.maxCombinedDrawBuffersAndPixelLocalStoragePlanes,
                             plsDrawBuffers.data());

        // Clear the non-LOAD_OP_LOAD PLS planes now that their draw buffers are turned on.
        if (needsClear)
        {
            ScopedDisableScissor scopedDisableScissor(context);
            ClearBufferCommands clearBufferCommands(context);
            for (GLsizei i = 0; i < n; ++i)
            {
                GLenum loadop = loadops[i];
                if (loadop != GL_LOAD_OP_DISABLE_ANGLE && loadop != GL_LOAD_OP_LOAD_ANGLE)
                {
                    GLuint drawBufferIdx = GetDrawBufferIdx(caps, i);
                    getPlane(i).issueClearCommand(&clearBufferCommands, drawBufferIdx, loadop);
                }
            }
        }

        if (!context->getExtensions().shaderPixelLocalStorageCoherentANGLE)
        {
            // Insert a barrier if we aren't coherent, since the textures may have been rendered to
            // previously.
            barrier(context);
        }
    }

    void onEnd(Context *context, const GLenum storeops[]) override
    {
        GLsizei n        = context->getState().getPixelLocalStorageActivePlanes();
        const Caps &caps = context->getCaps();

        // Invalidate the non-preserved PLS attachments.
        DrawBuffersVector<GLenum> invalidateList;
        for (GLsizei i = n - 1; i >= 0; --i)
        {
            if (!getPlane(i).isActive())
            {
                continue;
            }
            if (storeops[i] != GL_STORE_OP_STORE_ANGLE || getPlane(i).isMemoryless())
            {
                int drawBufferIdx = GetDrawBufferIdx(caps, i);
                invalidateList.push_back(GL_COLOR_ATTACHMENT0 + drawBufferIdx);
            }
        }
        if (!invalidateList.empty())
        {
            context->invalidateFramebuffer(GL_DRAW_FRAMEBUFFER,
                                           static_cast<GLsizei>(invalidateList.size()),
                                           invalidateList.data());
        }

        bool hasIndexedBlendAndColorMask = context->getExtensions().drawBuffersIndexedAny();
        if (!hasIndexedBlendAndColorMask)
        {
            // Restore global blend and color mask. Validation should have ensured these didn't
            // change while pixel local storage was active.
            if (mBlendsToReEnable[0])
            {
                context->enable(GL_BLEND);
            }
            if (mColorMasksToRestore[0])
            {
                const std::array<bool, 4> &mask = mSavedColorMasks[0];
                context->colorMask(mask[0], mask[1], mask[2], mask[3]);
            }
        }

        for (GLsizei i = 0; i < n; ++i)
        {
            // Reset color attachments where PLS was attached. Validation should have already
            // ensured nothing was attached at these points when we activated pixel local storage,
            // and that nothing got attached during.
            GLuint drawBufferIdx   = GetDrawBufferIdx(caps, i);
            GLenum colorAttachment = GL_COLOR_ATTACHMENT0 + drawBufferIdx;
            context->framebufferTexture2D(GL_DRAW_FRAMEBUFFER, colorAttachment, TextureTarget::_2D,
                                          TextureID(), 0);

            if (hasIndexedBlendAndColorMask)
            {
                // Restore this draw buffer's blend and color mask. Validation should have ensured
                // these did not change while pixel local storage was active.
                if (mBlendsToReEnable[drawBufferIdx])
                {
                    context->enablei(GL_BLEND, drawBufferIdx);
                }
                if (mColorMasksToRestore[drawBufferIdx])
                {
                    const std::array<bool, 4> &mask = mSavedColorMasks[drawBufferIdx];
                    context->colorMaski(drawBufferIdx, mask[0], mask[1], mask[2], mask[3]);
                }
            }
        }

        // Restore the draw buffer state from before PLS was enabled.
        context->drawBuffers(static_cast<GLsizei>(mSavedDrawBuffers.size()),
                             mSavedDrawBuffers.data());
        mSavedDrawBuffers.clear();
    }

    void onBarrier(Context *context) override { context->framebufferFetchBarrier(); }

  private:
    static GLuint GetDrawBufferIdx(const Caps &caps, GLuint plsPlaneIdx)
    {
        // Bind the PLS attachments in reverse order from the rear. This way, the shader translator
        // doesn't need to know how many planes are going to be active in order to figure out plane
        // indices.
        return caps.maxCombinedDrawBuffersAndPixelLocalStoragePlanes - plsPlaneIdx - 1;
    }

    DrawBuffersVector<GLenum> mSavedDrawBuffers;
    DrawBufferMask mBlendsToReEnable;
    DrawBufferMask mColorMasksToRestore;
    DrawBuffersArray<std::array<bool, 4>> mSavedColorMasks;
};

// Implements ANGLE_shader_pixel_local_storage directly via EXT_shader_pixel_local_storage.
class PixelLocalStorageEXT : public PixelLocalStorage
{
  public:
    PixelLocalStorageEXT(const ShPixelLocalStorageOptions &plsOptions)
        : PixelLocalStorage(plsOptions)
    {
        ASSERT(mPLSOptions.type == ShPixelLocalStorageType::PixelLocalStorageEXT);
    }

  private:
    void onContextObjectsLost() override {}

    void onDeleteContextObjects(Context *) override {}

    void onBegin(Context *context, GLsizei n, const GLenum loadops[], Extents plsExtents) override
    {
        const State &state       = context->getState();
        Framebuffer *framebuffer = state.getDrawFramebuffer();

        // Remember the current draw buffer state so we can restore it during onEnd().
        const DrawBuffersVector<GLenum> &appDrawBuffers = framebuffer->getDrawBufferStates();
        mSavedDrawBuffers.resize(appDrawBuffers.size());
        std::copy(appDrawBuffers.begin(), appDrawBuffers.end(), mSavedDrawBuffers.begin());

        // Turn off draw buffers.
        context->drawBuffers(0, nullptr);

        // Save the default framebuffer width/height so we can restore it during onEnd().
        mSavedFramebufferDefaultWidth  = framebuffer->getDefaultWidth();
        mSavedFramebufferDefaultHeight = framebuffer->getDefaultHeight();

        // Specify the framebuffer width/height explicitly since we don't use color attachments in
        // this mode.
        context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_WIDTH,
                                       plsExtents.width);
        context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_HEIGHT,
                                       plsExtents.height);

        context->drawPixelLocalStorageEXTEnable(n, getPlanes(), loadops);

        memcpy(mActiveLoadOps.data(), loadops, sizeof(GLenum) * n);
    }

    void onEnd(Context *context, const GLenum storeops[]) override
    {
        context->drawPixelLocalStorageEXTDisable(getPlanes(), storeops);

        // Restore the default framebuffer width/height.
        context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_WIDTH,
                                       mSavedFramebufferDefaultWidth);
        context->framebufferParameteri(GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_HEIGHT,
                                       mSavedFramebufferDefaultHeight);

        // Restore the draw buffer state from before PLS was enabled.
        context->drawBuffers(static_cast<GLsizei>(mSavedDrawBuffers.size()),
                             mSavedDrawBuffers.data());
        mSavedDrawBuffers.clear();
    }

    void onBarrier(Context *context) override { UNREACHABLE(); }

    // Saved values to restore during onEnd().
    GLint mSavedFramebufferDefaultWidth;
    GLint mSavedFramebufferDefaultHeight;
    DrawBuffersVector<GLenum> mSavedDrawBuffers;

    std::array<GLenum, IMPLEMENTATION_MAX_PIXEL_LOCAL_STORAGE_PLANES> mActiveLoadOps;
};
}  // namespace

std::unique_ptr<PixelLocalStorage> PixelLocalStorage::Make(const Context *context)
{
    const ShPixelLocalStorageOptions &plsOptions =
        context->getImplementation()->getNativePixelLocalStorageOptions();
    switch (plsOptions.type)
    {
        case ShPixelLocalStorageType::ImageLoadStore:
            return std::make_unique<PixelLocalStorageImageLoadStore>(plsOptions);
        case ShPixelLocalStorageType::FramebufferFetch:
            return std::make_unique<PixelLocalStorageFramebufferFetch>(plsOptions);
        case ShPixelLocalStorageType::PixelLocalStorageEXT:
            return std::make_unique<PixelLocalStorageEXT>(plsOptions);
        default:
            UNREACHABLE();
            return nullptr;
    }
}
}  // namespace gl