ValidateLimitations.cpp

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Author : Olli Etuaho
Date : 2015-12-11 12:24:21
Hash : 8e89866d
Message : Remove redundant index integer check from ValidateLimitations Non-integer indices are already rejected in the parser, so the ValidateLimitations pass doesn't need to check for them. ESSL 1.00 spec is not actually terribly clear about whether the parser should do this check, but the language grammar in the spec only has indexing with "integer_expression" so it seems like ANGLE's interpretation of only allowing indexing with integers is correct. ESSL 3.00 makes this restriction explicitly clear in section 5.7. BUG=angleproject:1254 TEST=angle_unittests Change-Id: I02b2a6f4d9fa7801a98df63ed21bc990e1585eb8 Reviewed-on: https://chromium-review.googlesource.com/317741 Reviewed-by: Zhenyao Mo <zmo@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>
src/compiler/translator/ValidateLimitations.cpp
//
// Copyright (c) 2002-2013 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 "compiler/translator/InfoSink.h"
#include "compiler/translator/InitializeParseContext.h"
#include "compiler/translator/ParseContext.h"
#include "angle_gl.h"

namespace
{

// 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(TLoopStack& stack)
        : TIntermTraverser(true, false, false),
          mValid(true),
          mLoopStack(stack)
    {
    }

    // 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)
        {
            mValid = (symbol->getQualifier() == EvqConst) ||
                     (mLoopStack.findLoop(symbol));
        }
    }

  private:
    bool mValid;
    TLoopStack& mLoopStack;
};

}  // namespace anonymous

ValidateLimitations::ValidateLimitations(sh::GLenum shaderType, TInfoSinkBase *sink)
    : TIntermTraverser(true, false, false),
      mShaderType(shaderType),
      mSink(sink),
      mNumErrors(0),
      mValidateIndexing(true),
      mValidateInnerLoops(true)
{
}

// static
bool ValidateLimitations::IsLimitedForLoop(TIntermLoop *loop)
{
    // The shader type doesn't matter in this case.
    ValidateLimitations validate(GL_FRAGMENT_SHADER, nullptr);
    validate.mValidateIndexing   = false;
    validate.mValidateInnerLoops = false;
    if (!validate.validateLoopType(loop))
        return false;
    if (!validate.validateForLoopHeader(loop))
        return false;
    TIntermNode *body = loop->getBody();
    if (body != nullptr)
    {
        validate.mLoopStack.push(loop);
        body->traverse(&validate);
        validate.mLoopStack.pop();
    }
    return (validate.mNumErrors == 0);
}

bool ValidateLimitations::visitBinary(Visit, TIntermBinary *node)
{
    // Check if loop index is modified in the loop body.
    validateOperation(node, node->getLeft());

    // Check indexing.
    switch (node->getOp())
    {
      case EOpIndexDirect:
      case EOpIndexIndirect:
          if (mValidateIndexing)
              validateIndexing(node);
          break;
      default:
          break;
    }
    return true;
}

bool ValidateLimitations::visitUnary(Visit, TIntermUnary *node)
{
    // Check if loop index is modified in the loop body.
    validateOperation(node, node->getOperand());

    return true;
}

bool ValidateLimitations::visitAggregate(Visit, TIntermAggregate *node)
{
    switch (node->getOp()) {
      case EOpFunctionCall:
        validateFunctionCall(node);
        break;
      default:
        break;
    }
    return true;
}

bool ValidateLimitations::visitLoop(Visit, TIntermLoop *node)
{
    if (!mValidateInnerLoops)
        return true;

    if (!validateLoopType(node))
        return false;

    if (!validateForLoopHeader(node))
        return false;

    TIntermNode *body = node->getBody();
    if (body != NULL)
    {
        mLoopStack.push(node);
        body->traverse(this);
        mLoopStack.pop();
    }

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

void ValidateLimitations::error(TSourceLoc loc,
                                const char *reason, const char *token)
{
    if (mSink)
    {
        mSink->prefix(EPrefixError);
        mSink->location(loc);
        (*mSink) << "'" << token << "' : " << reason << "\n";
    }
    ++mNumErrors;
}

bool ValidateLimitations::withinLoopBody() const
{
    return !mLoopStack.empty();
}

bool ValidateLimitations::isLoopIndex(TIntermSymbol *symbol)
{
    return mLoopStack.findLoop(symbol) != NULL;
}

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

    //
    // init-declaration has the form:
    //     type-specifier identifier = constant-expression
    //
    TIntermAggregate *decl = init->getAsAggregate();
    if ((decl == NULL) || (decl->getOp() != EOpDeclaration))
    {
        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 == NULL) || (declInit->getOp() != EOpInitialize))
    {
        error(decl->getLine(), "Invalid init declaration", "for");
        return -1;
    }
    TIntermSymbol *symbol = declInit->getLeft()->getAsSymbolNode();
    if (symbol == NULL)
    {
        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->getSymbol().c_str());
        return -1;
    }

    return symbol->getId();
}

bool ValidateLimitations::validateForLoopCond(TIntermLoop *node,
                                              int indexSymbolId)
{
    TIntermNode *cond = node->getCondition();
    if (cond == NULL)
    {
        error(node->getLine(), "Missing condition", "for");
        return false;
    }
    //
    // condition has the form:
    //     loop_index relational_operator constant_expression
    //
    TIntermBinary *binOp = cond->getAsBinaryNode();
    if (binOp == NULL)
    {
        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 == NULL)
    {
        error(binOp->getLine(), "Invalid condition", "for");
        return false;
    }
    if (symbol->getId() != indexSymbolId)
    {
        error(symbol->getLine(),
              "Expected loop index", symbol->getSymbol().c_str());
        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->getSymbol().c_str());
        return false;
    }

    return true;
}

bool ValidateLimitations::validateForLoopExpr(TIntermLoop *node,
                                              int indexSymbolId)
{
    TIntermNode *expr = node->getExpression();
    if (expr == NULL)
    {
        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 ? NULL : expr->getAsBinaryNode();

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

    // The operand must be loop index.
    if (symbol == NULL)
    {
        error(expr->getLine(), "Invalid expression", "for");
        return false;
    }
    if (symbol->getId() != indexSymbolId)
    {
        error(symbol->getLine(),
              "Expected loop index", symbol->getSymbol().c_str());
        return false;
    }

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

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

    return true;
}

bool ValidateLimitations::validateFunctionCall(TIntermAggregate *node)
{
    ASSERT(node->getOp() == EOpFunctionCall);

    // If not within loop body, there is nothing to check.
    if (!withinLoopBody())
        return true;

    // List of param indices for which loop indices are used as argument.
    typedef std::vector<size_t> ParamIndex;
    ParamIndex pIndex;
    TIntermSequence *params = node->getSequence();
    for (TIntermSequence::size_type i = 0; i < params->size(); ++i)
    {
        TIntermSymbol *symbol = (*params)[i]->getAsSymbolNode();
        if (symbol && isLoopIndex(symbol))
            pIndex.push_back(i);
    }
    // If none of the loop indices are used as arguments,
    // there is nothing to check.
    if (pIndex.empty())
        return true;

    bool valid = true;
    TSymbolTable& symbolTable = GetGlobalParseContext()->symbolTable;
    TSymbol* symbol = symbolTable.find(node->getName(), GetGlobalParseContext()->getShaderVersion());
    ASSERT(symbol && symbol->isFunction());
    TFunction *function = static_cast<TFunction *>(symbol);
    for (ParamIndex::const_iterator i = pIndex.begin();
         i != pIndex.end(); ++i)
    {
        const TConstParameter &param = function->getParam(*i);
        TQualifier qual = param.type->getQualifier();
        if ((qual == EvqOut) || (qual == EvqInOut))
        {
            error((*params)[*i]->getLine(),
                  "Loop index cannot be used as argument to a function out or inout parameter",
                  (*params)[*i]->getAsSymbolNode()->getSymbol().c_str());
            valid = false;
        }
    }

    return valid;
}

bool ValidateLimitations::validateOperation(TIntermOperator *node,
                                            TIntermNode* operand)
{
    // Check if loop index is modified in the loop body.
    if (!withinLoopBody() || !node->isAssignment())
        return true;

    TIntermSymbol *symbol = operand->getAsSymbolNode();
    if (symbol && isLoopIndex(symbol))
    {
        error(node->getLine(),
              "Loop index cannot be statically assigned to within the body of the loop",
              symbol->getSymbol().c_str());
    }
    return true;
}

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

bool ValidateLimitations::isConstIndexExpr(TIntermNode *node)
{
    ASSERT(node != NULL);

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

bool ValidateLimitations::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;
}
kc3-lang/angle/src/compiler/translator/ValidateLimitations.cpp

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