ValidateLimitations.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/ValidateLimitations.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.
//

#include "compiler/translator/ValidateLimitations.h"

#include "angle_gl.h"
#include "compiler/translator/Diagnostics.h"
#include "compiler/translator/ParseContext.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{

namespace
{

int GetLoopSymbolId(TIntermLoop *loop)
{
    // Here we assume all the operations are valid, because the loop node is
    // already validated before this call.
    TIntermSequence *declSeq = loop->getInit()->getAsDeclarationNode()->getSequence();
    TIntermBinary *declInit  = (*declSeq)[0]->getAsBinaryNode();
    TIntermSymbol *symbol    = declInit->getLeft()->getAsSymbolNode();

    return symbol->uniqueId().get();
}

// Traverses a node to check if it represents a constant index expression.
// Definition:
// constant-index-expressions are a superset of constant-expressions.
// Constant-index-expressions can include loop indices as defined in
// GLSL ES 1.0 spec, Appendix A, section 4.
// The following are constant-index-expressions:
// - Constant expressions
// - Loop indices as defined in section 4
// - Expressions composed of both of the above
class ValidateConstIndexExpr : public TIntermTraverser
{
  public:
    ValidateConstIndexExpr(const std::vector<int> &loopSymbols)
        : TIntermTraverser(true, false, false), mValid(true), mLoopSymbolIds(loopSymbols)
    {}

    // Returns true if the parsed node represents a constant index expression.
    bool isValid() const { return mValid; }

    void visitSymbol(TIntermSymbol *symbol) override
    {
        // Only constants and loop indices are allowed in a
        // constant index expression.
        if (mValid)
        {
            bool isLoopSymbol = std::find(mLoopSymbolIds.begin(), mLoopSymbolIds.end(),
                                          symbol->uniqueId().get()) != mLoopSymbolIds.end();
            mValid            = (symbol->getQualifier() == EvqConst) || isLoopSymbol;
        }
    }

  private:
    bool mValid;
    const std::vector<int> mLoopSymbolIds;
};

// Traverses intermediate tree to ensure that the shader does not exceed the
// minimum functionality mandated in GLSL 1.0 spec, Appendix A.
class ValidateLimitationsTraverser : public TLValueTrackingTraverser
{
  public:
    ValidateLimitationsTraverser(sh::GLenum shaderType,
                                 TSymbolTable *symbolTable,
                                 TDiagnostics *diagnostics);

    void visitSymbol(TIntermSymbol *node) override;
    bool visitBinary(Visit, TIntermBinary *) override;
    bool visitLoop(Visit, TIntermLoop *) override;

  private:
    void error(TSourceLoc loc, const char *reason, const char *token);
    void error(TSourceLoc loc, const char *reason, const ImmutableString &token);

    bool isLoopIndex(TIntermSymbol *symbol);
    bool validateLoopType(TIntermLoop *node);

    bool validateForLoopHeader(TIntermLoop *node);
    // If valid, return the index symbol id; Otherwise, return -1.
    int validateForLoopInit(TIntermLoop *node);
    bool validateForLoopCond(TIntermLoop *node, int indexSymbolId);
    bool validateForLoopExpr(TIntermLoop *node, int indexSymbolId);

    // Returns true if indexing does not exceed the minimum functionality
    // mandated in GLSL 1.0 spec, Appendix A, Section 5.
    bool isConstExpr(TIntermNode *node);
    bool isConstIndexExpr(TIntermNode *node);
    bool validateIndexing(TIntermBinary *node);

    sh::GLenum mShaderType;
    TDiagnostics *mDiagnostics;
    std::vector<int> mLoopSymbolIds;
};

ValidateLimitationsTraverser::ValidateLimitationsTraverser(sh::GLenum shaderType,
                                                           TSymbolTable *symbolTable,
                                                           TDiagnostics *diagnostics)
    : TLValueTrackingTraverser(true, false, false, symbolTable),
      mShaderType(shaderType),
      mDiagnostics(diagnostics)
{
    ASSERT(diagnostics);
}

void ValidateLimitationsTraverser::visitSymbol(TIntermSymbol *node)
{
    if (isLoopIndex(node) && isLValueRequiredHere())
    {
        error(node->getLine(),
              "Loop index cannot be statically assigned to within the body of the loop",
              node->getName());
    }
}

bool ValidateLimitationsTraverser::visitBinary(Visit, TIntermBinary *node)
{
    // Check indexing.
    switch (node->getOp())
    {
        case EOpIndexDirect:
        case EOpIndexIndirect:
            validateIndexing(node);
            break;
        default:
            break;
    }
    return true;
}

bool ValidateLimitationsTraverser::visitLoop(Visit, TIntermLoop *node)
{
    if (!validateLoopType(node))
        return false;

    if (!validateForLoopHeader(node))
        return false;

    TIntermNode *body = node->getBody();
    if (body != nullptr)
    {
        mLoopSymbolIds.push_back(GetLoopSymbolId(node));
        body->traverse(this);
        mLoopSymbolIds.pop_back();
    }

    // The loop is fully processed - no need to visit children.
    return false;
}

void ValidateLimitationsTraverser::error(TSourceLoc loc, const char *reason, const char *token)
{
    mDiagnostics->error(loc, reason, token);
}

void ValidateLimitationsTraverser::error(TSourceLoc loc,
                                         const char *reason,
                                         const ImmutableString &token)
{
    error(loc, reason, token.data());
}

bool ValidateLimitationsTraverser::isLoopIndex(TIntermSymbol *symbol)
{
    return std::find(mLoopSymbolIds.begin(), mLoopSymbolIds.end(), symbol->uniqueId().get()) !=
           mLoopSymbolIds.end();
}

bool ValidateLimitationsTraverser::validateLoopType(TIntermLoop *node)
{
    TLoopType type = node->getType();
    if (type == ELoopFor)
        return true;

    // Reject while and do-while loops.
    error(node->getLine(), "This type of loop is not allowed", type == ELoopWhile ? "while" : "do");
    return false;
}

bool ValidateLimitationsTraverser::validateForLoopHeader(TIntermLoop *node)
{
    ASSERT(node->getType() == ELoopFor);

    //
    // The for statement has the form:
    //    for ( init-declaration ; condition ; expression ) statement
    //
    int indexSymbolId = validateForLoopInit(node);
    if (indexSymbolId < 0)
        return false;
    if (!validateForLoopCond(node, indexSymbolId))
        return false;
    if (!validateForLoopExpr(node, indexSymbolId))
        return false;

    return true;
}

int ValidateLimitationsTraverser::validateForLoopInit(TIntermLoop *node)
{
    TIntermNode *init = node->getInit();
    if (init == nullptr)
    {
        error(node->getLine(), "Missing init declaration", "for");
        return -1;
    }

    //
    // init-declaration has the form:
    //     type-specifier identifier = constant-expression
    //
    TIntermDeclaration *decl = init->getAsDeclarationNode();
    if (decl == nullptr)
    {
        error(init->getLine(), "Invalid init declaration", "for");
        return -1;
    }
    // To keep things simple do not allow declaration list.
    TIntermSequence *declSeq = decl->getSequence();
    if (declSeq->size() != 1)
    {
        error(decl->getLine(), "Invalid init declaration", "for");
        return -1;
    }
    TIntermBinary *declInit = (*declSeq)[0]->getAsBinaryNode();
    if ((declInit == nullptr) || (declInit->getOp() != EOpInitialize))
    {
        error(decl->getLine(), "Invalid init declaration", "for");
        return -1;
    }
    TIntermSymbol *symbol = declInit->getLeft()->getAsSymbolNode();
    if (symbol == nullptr)
    {
        error(declInit->getLine(), "Invalid init declaration", "for");
        return -1;
    }
    // The loop index has type int or float.
    TBasicType type = symbol->getBasicType();
    if ((type != EbtInt) && (type != EbtUInt) && (type != EbtFloat))
    {
        error(symbol->getLine(), "Invalid type for loop index", getBasicString(type));
        return -1;
    }
    // The loop index is initialized with constant expression.
    if (!isConstExpr(declInit->getRight()))
    {
        error(declInit->getLine(), "Loop index cannot be initialized with non-constant expression",
              symbol->getName());
        return -1;
    }

    return symbol->uniqueId().get();
}

bool ValidateLimitationsTraverser::validateForLoopCond(TIntermLoop *node, int indexSymbolId)
{
    TIntermNode *cond = node->getCondition();
    if (cond == nullptr)
    {
        error(node->getLine(), "Missing condition", "for");
        return false;
    }
    //
    // condition has the form:
    //     loop_index relational_operator constant_expression
    //
    TIntermBinary *binOp = cond->getAsBinaryNode();
    if (binOp == nullptr)
    {
        error(node->getLine(), "Invalid condition", "for");
        return false;
    }
    // Loop index should be to the left of relational operator.
    TIntermSymbol *symbol = binOp->getLeft()->getAsSymbolNode();
    if (symbol == nullptr)
    {
        error(binOp->getLine(), "Invalid condition", "for");
        return false;
    }
    if (symbol->uniqueId().get() != indexSymbolId)
    {
        error(symbol->getLine(), "Expected loop index", symbol->getName());
        return false;
    }
    // Relational operator is one of: > >= < <= == or !=.
    switch (binOp->getOp())
    {
        case EOpEqual:
        case EOpNotEqual:
        case EOpLessThan:
        case EOpGreaterThan:
        case EOpLessThanEqual:
        case EOpGreaterThanEqual:
            break;
        default:
            error(binOp->getLine(), "Invalid relational operator",
                  GetOperatorString(binOp->getOp()));
            break;
    }
    // Loop index must be compared with a constant.
    if (!isConstExpr(binOp->getRight()))
    {
        error(binOp->getLine(), "Loop index cannot be compared with non-constant expression",
              symbol->getName());
        return false;
    }

    return true;
}

bool ValidateLimitationsTraverser::validateForLoopExpr(TIntermLoop *node, int indexSymbolId)
{
    TIntermNode *expr = node->getExpression();
    if (expr == nullptr)
    {
        error(node->getLine(), "Missing expression", "for");
        return false;
    }

    // for expression has one of the following forms:
    //     loop_index++
    //     loop_index--
    //     loop_index += constant_expression
    //     loop_index -= constant_expression
    //     ++loop_index
    //     --loop_index
    // The last two forms are not specified in the spec, but I am assuming
    // its an oversight.
    TIntermUnary *unOp   = expr->getAsUnaryNode();
    TIntermBinary *binOp = unOp ? nullptr : expr->getAsBinaryNode();

    TOperator op          = EOpNull;
    TIntermSymbol *symbol = nullptr;
    if (unOp != nullptr)
    {
        op     = unOp->getOp();
        symbol = unOp->getOperand()->getAsSymbolNode();
    }
    else if (binOp != nullptr)
    {
        op     = binOp->getOp();
        symbol = binOp->getLeft()->getAsSymbolNode();
    }

    // The operand must be loop index.
    if (symbol == nullptr)
    {
        error(expr->getLine(), "Invalid expression", "for");
        return false;
    }
    if (symbol->uniqueId().get() != indexSymbolId)
    {
        error(symbol->getLine(), "Expected loop index", symbol->getName());
        return false;
    }

    // The operator is one of: ++ -- += -=.
    switch (op)
    {
        case EOpPostIncrement:
        case EOpPostDecrement:
        case EOpPreIncrement:
        case EOpPreDecrement:
            ASSERT((unOp != nullptr) && (binOp == nullptr));
            break;
        case EOpAddAssign:
        case EOpSubAssign:
            ASSERT((unOp == nullptr) && (binOp != nullptr));
            break;
        default:
            error(expr->getLine(), "Invalid operator", GetOperatorString(op));
            return false;
    }

    // Loop index must be incremented/decremented with a constant.
    if (binOp != nullptr)
    {
        if (!isConstExpr(binOp->getRight()))
        {
            error(binOp->getLine(), "Loop index cannot be modified by non-constant expression",
                  symbol->getName());
            return false;
        }
    }

    return true;
}

bool ValidateLimitationsTraverser::isConstExpr(TIntermNode *node)
{
    ASSERT(node != nullptr);
    return node->getAsConstantUnion() != nullptr && node->getAsTyped()->getQualifier() == EvqConst;
}

bool ValidateLimitationsTraverser::isConstIndexExpr(TIntermNode *node)
{
    ASSERT(node != nullptr);

    ValidateConstIndexExpr validate(mLoopSymbolIds);
    node->traverse(&validate);
    return validate.isValid();
}

bool ValidateLimitationsTraverser::validateIndexing(TIntermBinary *node)
{
    ASSERT((node->getOp() == EOpIndexDirect) || (node->getOp() == EOpIndexIndirect));

    bool valid          = true;
    TIntermTyped *index = node->getRight();
    // The index expession must be a constant-index-expression unless
    // the operand is a uniform in a vertex shader.
    TIntermTyped *operand = node->getLeft();
    bool skip = (mShaderType == GL_VERTEX_SHADER) && (operand->getQualifier() == EvqUniform);
    if (!skip && !isConstIndexExpr(index))
    {
        error(index->getLine(), "Index expression must be constant", "[]");
        valid = false;
    }
    return valid;
}

}  // namespace

bool ValidateLimitations(TIntermNode *root,
                         GLenum shaderType,
                         TSymbolTable *symbolTable,
                         TDiagnostics *diagnostics)
{
    ValidateLimitationsTraverser validate(shaderType, symbolTable, diagnostics);
    root->traverse(&validate);
    return diagnostics->numErrors() == 0;
}

}  // namespace sh
kc3-lang/angle/src/compiler/translator/ValidateLimitations.cpp

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kc3-lang/angle /src/compiler/translator/ValidateLimitations.cpp
