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//
// 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.
//
// RewriteRepeatedAssignToSwizzled.cpp: Rewrite expressions that assign an assignment to a swizzled
// vector, like:
// v.x = z = expression;
// to:
// z = expression;
// v.x = z;
//
// Note that this doesn't handle some corner cases: expressions nested inside other expressions,
// inside loop headers, or inside if conditions.
#include "compiler/translator/tree_ops/gl/RewriteRepeatedAssignToSwizzled.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/IntermTraverse.h"
namespace sh
{
namespace
{
class RewriteAssignToSwizzledTraverser : public TIntermTraverser
{
public:
[[nodiscard]] static bool rewrite(TCompiler *compiler, TIntermBlock *root);
private:
RewriteAssignToSwizzledTraverser();
bool visitBinary(Visit, TIntermBinary *node) override;
void nextIteration();
bool didRewrite() { return mDidRewrite; }
bool mDidRewrite;
};
// static
bool RewriteAssignToSwizzledTraverser::rewrite(TCompiler *compiler, TIntermBlock *root)
{
RewriteAssignToSwizzledTraverser rewrite;
do
{
rewrite.nextIteration();
root->traverse(&rewrite);
if (!rewrite.updateTree(compiler, root))
{
return false;
}
} while (rewrite.didRewrite());
return true;
}
RewriteAssignToSwizzledTraverser::RewriteAssignToSwizzledTraverser()
: TIntermTraverser(true, false, false), mDidRewrite(false)
{}
void RewriteAssignToSwizzledTraverser::nextIteration()
{
mDidRewrite = false;
}
bool RewriteAssignToSwizzledTraverser::visitBinary(Visit, TIntermBinary *node)
{
TIntermBinary *rightBinary = node->getRight()->getAsBinaryNode();
TIntermBlock *parentBlock = getParentNode()->getAsBlock();
if (parentBlock && node->isAssignment() && node->getLeft()->getAsSwizzleNode() && rightBinary &&
rightBinary->isAssignment())
{
TIntermSequence replacements;
replacements.push_back(rightBinary);
TIntermTyped *rightAssignmentTargetCopy = rightBinary->getLeft()->deepCopy();
TIntermBinary *lastAssign =
new TIntermBinary(EOpAssign, node->getLeft(), rightAssignmentTargetCopy);
replacements.push_back(lastAssign);
mMultiReplacements.emplace_back(parentBlock, node, std::move(replacements));
mDidRewrite = true;
return false;
}
return true;
}
} // anonymous namespace
bool RewriteRepeatedAssignToSwizzled(TCompiler *compiler, TIntermBlock *root)
{
return RewriteAssignToSwizzledTraverser::rewrite(compiler, root);
}
} // namespace sh