PruneNoOps.cpp

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Author : Stuart Morgan
Date : 2019-08-14 12:25:12
Hash : 9d737966
Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/compiler/translator/tree_ops/PruneNoOps.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.
//
// PruneNoOps.cpp: The PruneNoOps function prunes:
//   1. Empty declarations "int;". Empty declarators will be pruned as well, so for example:
//        int , a;
//      is turned into
//        int a;
//   2. Literal statements: "1.0;". The ESSL output doesn't define a default precision for float,
//      so float literal statements would end up with no precision which is invalid ESSL.

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

#include "compiler/translator/Symbol.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{

namespace
{

bool IsNoOp(TIntermNode *node)
{
    if (node->getAsConstantUnion() != nullptr)
    {
        return true;
    }
    bool isEmptyDeclaration = node->getAsDeclarationNode() != nullptr &&
                              node->getAsDeclarationNode()->getSequence()->empty();
    if (isEmptyDeclaration)
    {
        return true;
    }
    return false;
}

class PruneNoOpsTraverser : private TIntermTraverser
{
  public:
    static void apply(TIntermBlock *root, TSymbolTable *symbolTable);

  private:
    PruneNoOpsTraverser(TSymbolTable *symbolTable);
    bool visitDeclaration(Visit, TIntermDeclaration *node) override;
    bool visitBlock(Visit visit, TIntermBlock *node) override;
    bool visitLoop(Visit visit, TIntermLoop *loop) override;
};

void PruneNoOpsTraverser::apply(TIntermBlock *root, TSymbolTable *symbolTable)
{
    PruneNoOpsTraverser prune(symbolTable);
    root->traverse(&prune);
    prune.updateTree();
}

PruneNoOpsTraverser::PruneNoOpsTraverser(TSymbolTable *symbolTable)
    : TIntermTraverser(true, false, false, symbolTable)
{}

bool PruneNoOpsTraverser::visitDeclaration(Visit, TIntermDeclaration *node)
{
    TIntermSequence *sequence = node->getSequence();
    if (sequence->size() >= 1)
    {
        TIntermSymbol *declaratorSymbol = sequence->front()->getAsSymbolNode();
        // Prune declarations without a variable name, unless it's an interface block declaration.
        if (declaratorSymbol != nullptr &&
            declaratorSymbol->variable().symbolType() == SymbolType::Empty &&
            !declaratorSymbol->isInterfaceBlock())
        {
            if (sequence->size() > 1)
            {
                // Generate a replacement that will remove the empty declarator in the beginning of
                // a declarator list. Example of a declaration that will be changed:
                // float, a;
                // will be changed to
                // float a;
                // This applies also to struct declarations.
                TIntermSequence emptyReplacement;
                mMultiReplacements.push_back(
                    NodeReplaceWithMultipleEntry(node, declaratorSymbol, emptyReplacement));
            }
            else if (declaratorSymbol->getBasicType() != EbtStruct)
            {
                // If there are entirely empty non-struct declarations, they result in
                // TIntermDeclaration nodes without any children in the parsing stage. These are
                // handled in visitBlock and visitLoop.
                UNREACHABLE();
            }
            else if (declaratorSymbol->getQualifier() != EvqGlobal &&
                     declaratorSymbol->getQualifier() != EvqTemporary)
            {
                // Single struct declarations may just declare the struct type and no variables, so
                // they should not be pruned. Here we handle an empty struct declaration with a
                // qualifier, for example like this:
                //   const struct a { int i; };
                // NVIDIA GL driver version 367.27 doesn't accept this kind of declarations, so we
                // convert the declaration to a regular struct declaration. This is okay, since ESSL
                // 1.00 spec section 4.1.8 says about structs that "The optional qualifiers only
                // apply to any declarators, and are not part of the type being defined for name."

                // Create a new variable to use in the declarator so that the variable and node
                // types are kept consistent.
                TType *type = new TType(declaratorSymbol->getType());
                if (mInGlobalScope)
                {
                    type->setQualifier(EvqGlobal);
                }
                else
                {
                    type->setQualifier(EvqTemporary);
                }
                TVariable *variable =
                    new TVariable(mSymbolTable, kEmptyImmutableString, type, SymbolType::Empty);
                queueReplacementWithParent(node, declaratorSymbol, new TIntermSymbol(variable),
                                           OriginalNode::IS_DROPPED);
            }
        }
    }
    return false;
}

bool PruneNoOpsTraverser::visitBlock(Visit visit, TIntermBlock *node)
{
    TIntermSequence *statements = node->getSequence();

    for (TIntermNode *statement : *statements)
    {
        if (IsNoOp(statement))
        {
            TIntermSequence emptyReplacement;
            mMultiReplacements.push_back(
                NodeReplaceWithMultipleEntry(node, statement, emptyReplacement));
        }
    }

    return true;
}

bool PruneNoOpsTraverser::visitLoop(Visit visit, TIntermLoop *loop)
{
    TIntermTyped *expr = loop->getExpression();
    if (expr != nullptr && IsNoOp(expr))
    {
        loop->setExpression(nullptr);
    }
    TIntermNode *init = loop->getInit();
    if (init != nullptr && IsNoOp(init))
    {
        loop->setInit(nullptr);
    }

    return true;
}

}  // namespace

void PruneNoOps(TIntermBlock *root, TSymbolTable *symbolTable)
{
    PruneNoOpsTraverser::apply(root, symbolTable);
}

}  // namespace sh

kc3-lang/angle/src/compiler/translator/tree_ops/PruneNoOps.cpp

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kc3-lang/angle /src/compiler/translator/tree_ops/PruneNoOps.cpp