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

//
// Copyright 2002 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.
//
// RemoveDynamicIndexing is an AST traverser to remove dynamic indexing of non-SSBO vectors and
// matrices, replacing them with calls to functions that choose which component to return or write.
// We don't need to consider dynamic indexing in SSBO since it can be directly as part of the offset
// of RWByteAddressBuffer.
//

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

#include "compiler/translator/Compiler.h"
#include "compiler/translator/Diagnostics.h"
#include "compiler/translator/InfoSink.h"
#include "compiler/translator/StaticType.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/tree_util/IntermNodePatternMatcher.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{

namespace
{

DynamicIndexingNodeMatcher;

const TType *kIndexType = …;

constexpr const ImmutableString kBaseName("base");
constexpr const ImmutableString kIndexName("index");
constexpr const ImmutableString kValueName("value");

std::string GetIndexFunctionName(const TType &type, bool write)
{ … }

TIntermConstantUnion *CreateIntConstantNode(int i)
{ … }

TIntermTyped *EnsureSignedInt(TIntermTyped *node)
{ … }

TType *GetFieldType(const TType &indexedType)
{ … }

const TType *GetBaseType(const TType &type, bool write)
{ … }

// Generate a read or write function for one field in a vector/matrix.
// Out-of-range indices are clamped. This is consistent with how ANGLE handles out-of-range
// indices in other places.
// Note that indices can be either int or uint. We create only int versions of the functions,
// and convert uint indices to int at the call site.
// read function example:
// float dyn_index_vec2(in vec2 base, in int index)
// {
//    switch(index)
//    {
//      case (0):
//        return base[0];
//      case (1):
//        return base[1];
//      default:
//        break;
//    }
//    if (index < 0)
//      return base[0];
//    return base[1];
// }
// write function example:
// void dyn_index_write_vec2(inout vec2 base, in int index, in float value)
// {
//    switch(index)
//    {
//      case (0):
//        base[0] = value;
//        return;
//      case (1):
//        base[1] = value;
//        return;
//      default:
//        break;
//    }
//    if (index < 0)
//    {
//      base[0] = value;
//      return;
//    }
//    base[1] = value;
// }
// Note that else is not used in above functions to avoid the RewriteElseBlocks transformation.
TIntermFunctionDefinition *GetIndexFunctionDefinition(const TType &type,
                                                      bool write,
                                                      const TFunction &func,
                                                      TSymbolTable *symbolTable)
{ … }

class RemoveDynamicIndexingTraverser : public TLValueTrackingTraverser
{ … };

RemoveDynamicIndexingTraverser::RemoveDynamicIndexingTraverser(
    DynamicIndexingNodeMatcher &&matcher,
    TSymbolTable *symbolTable,
    PerformanceDiagnostics *perfDiagnostics)
    : … { … }

void RemoveDynamicIndexingTraverser::insertHelperDefinitions(TIntermNode *root)
{ … }

// Create a call to dyn_index_*() based on an indirect indexing op node
TIntermAggregate *CreateIndexFunctionCall(TIntermBinary *node,
                                          TIntermTyped *index,
                                          TFunction *indexingFunction)
{ … }

TIntermAggregate *CreateIndexedWriteFunctionCall(TIntermBinary *node,
                                                 TVariable *index,
                                                 TVariable *writtenValue,
                                                 TFunction *indexedWriteFunction)
{ … }

bool RemoveDynamicIndexingTraverser::visitBinary(Visit visit, TIntermBinary *node)
{ … }

void RemoveDynamicIndexingTraverser::nextIteration()
{ … }

bool RemoveDynamicIndexingIf(DynamicIndexingNodeMatcher &&matcher,
                             TCompiler *compiler,
                             TIntermNode *root,
                             TSymbolTable *symbolTable,
                             PerformanceDiagnostics *perfDiagnostics)
{ … }

}  // namespace

[[nodiscard]] bool RemoveDynamicIndexingOfNonSSBOVectorOrMatrix(
    TCompiler *compiler,
    TIntermNode *root,
    TSymbolTable *symbolTable,
    PerformanceDiagnostics *perfDiagnostics)
{ … }

[[nodiscard]] bool RemoveDynamicIndexingOfSwizzledVector(TCompiler *compiler,
                                                         TIntermNode *root,
                                                         TSymbolTable *symbolTable,
                                                         PerformanceDiagnostics *perfDiagnostics)
{ … }

}  // namespace sh