chromium/third_party/angle/src/compiler/translator/tree_ops/RewriteStructSamplers.cpp

//
// Copyright 2018 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.
//
// RewriteStructSamplers: Extract samplers from structs.
//

#include "compiler/translator/tree_ops/RewriteStructSamplers.h"

#include "common/hash_containers.h"
#include "compiler/translator/ImmutableStringBuilder.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{
namespace
{

// Used to map one structure type to another (one where the samplers are removed).
struct StructureData
{ … };

StructureMap;
StructureUniformMap;
ExtractedSamplerMap;

TIntermTyped *RewriteModifiedStructFieldSelectionExpression(
    TCompiler *compiler,
    TIntermBinary *node,
    const StructureMap &structureMap,
    const StructureUniformMap &structureUniformMap,
    const ExtractedSamplerMap &extractedSamplers);

TIntermTyped *RewriteExpressionVisitBinaryHelper(TCompiler *compiler,
                                                 TIntermBinary *node,
                                                 const StructureMap &structureMap,
                                                 const StructureUniformMap &structureUniformMap,
                                                 const ExtractedSamplerMap &extractedSamplers)
{ … }

// Given an expression, this traverser calculates a new expression where sampler-in-structs are
// replaced with their extracted ones, and field indices are adjusted for the rest of the fields.
// In particular, this is run on the right node of EOpIndexIndirect binary nodes, so that the
// expression in the index gets a chance to go through this transformation.
class RewriteExpressionTraverser final : public TIntermTraverser
{ … };

// Rewrite the index of an EOpIndexIndirect expression.  The root can never need replacing, because
// it cannot be a sampler itself or of a struct type.
void RewriteIndexExpression(TCompiler *compiler,
                            TIntermTyped *expression,
                            const StructureMap &structureMap,
                            const StructureUniformMap &structureUniformMap,
                            const ExtractedSamplerMap &extractedSamplers)
{ … }

// Given an expression such as the following:
//
//                                                    EOpIndexDirectStruct (sampler)
//                                                    /                  \
//                                               EOpIndex*           field index
//                                              /        \
//                                EOpIndexDirectStruct   index 2
//                                /                  \
//                           EOpIndex*           field index
//                          /        \
//            EOpIndexDirectStruct   index 1
//            /                  \
//     Uniform Struct           field index
//
// produces:
//
//                                EOpIndex*
//                                /      \
//                           EOpIndex*  index 2
//                          /        \
//                      sampler    index 1
//
// If the expression is not a sampler, it only replaces the struct with the modified one, while
// still processing the EOpIndexIndirect expressions (which may contain more structs to map).
TIntermTyped *RewriteModifiedStructFieldSelectionExpression(
    TCompiler *compiler,
    TIntermBinary *node,
    const StructureMap &structureMap,
    const StructureUniformMap &structureUniformMap,
    const ExtractedSamplerMap &extractedSamplers)
{ … }

class RewriteStructSamplersTraverser final : public TIntermTraverser
{ … };
}  // anonymous namespace

bool RewriteStructSamplers(TCompiler *compiler,
                           TIntermBlock *root,
                           TSymbolTable *symbolTable,
                           int *removedUniformsCountOut)
{ … }
}  // namespace sh