ValidateLimitations.cpp

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Author : shannon.woods@transgaming.com
Date : 2013-02-28 23:19:26
Hash : d64b3dab
Message : Fixed 64-bit integer truncation issues in shader translator. This is an incompatible API change, but one which is necessary in order to improve correctness of the code. The API version in ShaderLang.h is updated and, unfortunately, the define renamed to something less ambiguous due to conflicts on some Android buildbots. Temporary patches in Chromium and WebKit will be landed separately to support this upgrade. BUG=403,404,405,406,407,408,409 Review URL: https://codereview.appspot.com/7300058 Conflicts: include/GLSLANG/ShaderLang.h git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1960 736b8ea6-26fd-11df-bfd4-992fa37f6226
src/compiler/ValidateLimitations.cpp
//
// Copyright (c) 2002-2010 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/ValidateLimitations.h"
#include "compiler/InfoSink.h"
#include "compiler/InitializeParseContext.h"
#include "compiler/ParseHelper.h"

namespace {
bool IsLoopIndex(const TIntermSymbol* symbol, const TLoopStack& stack) {
    for (TLoopStack::const_iterator i = stack.begin(); i != stack.end(); ++i) {
        if (i->index.id == symbol->getId())
            return true;
    }
    return false;
}

void MarkLoopForUnroll(const TIntermSymbol* symbol, TLoopStack& stack) {
    for (TLoopStack::iterator i = stack.begin(); i != stack.end(); ++i) {
        if (i->index.id == symbol->getId()) {
            ASSERT(i->loop != NULL);
            i->loop->setUnrollFlag(true);
            return;
        }
    }
    UNREACHABLE();
}

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

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

    virtual void visitSymbol(TIntermSymbol* symbol) {
        // Only constants and loop indices are allowed in a
        // constant index expression.
        if (mValid) {
            mValid = (symbol->getQualifier() == EvqConst) ||
                     IsLoopIndex(symbol, mLoopStack);
        }
    }

private:
    bool mValid;
    const TLoopStack& mLoopStack;
};

// Traverses a node to check if it uses a loop index.
// If an int loop index is used in its body as a sampler array index,
// mark the loop for unroll.
class ValidateLoopIndexExpr : public TIntermTraverser {
public:
    ValidateLoopIndexExpr(TLoopStack& stack)
        : mUsesFloatLoopIndex(false),
          mUsesIntLoopIndex(false),
          mLoopStack(stack) {}

    bool usesFloatLoopIndex() const { return mUsesFloatLoopIndex; }
    bool usesIntLoopIndex() const { return mUsesIntLoopIndex; }

    virtual void visitSymbol(TIntermSymbol* symbol) {
        if (IsLoopIndex(symbol, mLoopStack)) {
            switch (symbol->getBasicType()) {
              case EbtFloat:
                mUsesFloatLoopIndex = true;
                break;
              case EbtInt:
                mUsesIntLoopIndex = true;
                MarkLoopForUnroll(symbol, mLoopStack);
                break;
              default:
                UNREACHABLE();
            }
        }
    }

private:
    bool mUsesFloatLoopIndex;
    bool mUsesIntLoopIndex;
    TLoopStack& mLoopStack;
};
}  // namespace

ValidateLimitations::ValidateLimitations(ShShaderType shaderType,
                                         TInfoSinkBase& sink)
    : mShaderType(shaderType),
      mSink(sink),
      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:
        validateIndexing(node);
        break;
      case EOpIndexIndirect:
#if defined(__APPLE__)
        // Loop unrolling is a work-around for a Mac Cg compiler bug where it
        // crashes when a sampler array's index is also the loop index.
        // Once Apple fixes this bug, we should remove the code in this CL.
        // See http://codereview.appspot.com/4331048/.
        if ((node->getLeft() != NULL) && (node->getRight() != NULL) &&
            (node->getLeft()->getAsSymbolNode())) {
            TIntermSymbol* symbol = node->getLeft()->getAsSymbolNode();
            if (IsSampler(symbol->getBasicType()) && symbol->isArray()) {
                ValidateLoopIndexExpr validate(mLoopStack);
                node->getRight()->traverse(&validate);
                if (validate.usesFloatLoopIndex()) {
                    error(node->getLine(),
                          "sampler array index is float loop index",
                          "for");
                }
            }
        }
#endif
        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 (!validateLoopType(node))
        return false;

    TLoopInfo info;
    memset(&info, 0, sizeof(TLoopInfo));
    info.loop = node;
    if (!validateForLoopHeader(node, &info))
        return false;

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

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

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

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

bool ValidateLimitations::isLoopIndex(const TIntermSymbol* symbol) const
{
    return IsLoopIndex(symbol, mLoopStack);
}

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,
                                                TLoopInfo* info)
{
    ASSERT(node->getType() == ELoopFor);

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

    return true;
}

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

    //
    // 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 false;
    }
    // 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 false;
    }
    TIntermBinary* declInit = declSeq[0]->getAsBinaryNode();
    if ((declInit == NULL) || (declInit->getOp() != EOpInitialize)) {
        error(decl->getLine(), "Invalid init declaration", "for");
        return false;
    }
    TIntermSymbol* symbol = declInit->getLeft()->getAsSymbolNode();
    if (symbol == NULL) {
        error(declInit->getLine(), "Invalid init declaration", "for");
        return false;
    }
    // The loop index has type int or float.
    TBasicType type = symbol->getBasicType();
    if ((type != EbtInt) && (type != EbtFloat)) {
        error(symbol->getLine(),
              "Invalid type for loop index", getBasicString(type));
        return false;
    }
    // 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 false;
    }

    info->index.id = symbol->getId();
    return true;
}

bool ValidateLimitations::validateForLoopCond(TIntermLoop* node,
                                              TLoopInfo* info)
{
    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() != info->index.id) {
        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,
                                              TLoopInfo* info)
{
    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() != info->index.id) {
        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 = GlobalParseContext->symbolTable;
    TSymbol* symbol = symbolTable.find(node->getName());
    ASSERT(symbol && symbol->isFunction());
    TFunction* function = static_cast<TFunction*>(symbol);
    for (ParamIndex::const_iterator i = pIndex.begin();
         i != pIndex.end(); ++i) {
        const TParameter& 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->modifiesState())
        return true;

    const 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 != NULL);
    return node->getAsConstantUnion() != NULL;
}

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 expression must have integral type.
    if (!index->isScalar() || (index->getBasicType() != EbtInt)) {
        error(index->getLine(),
              "Index expression must have integral type",
              index->getCompleteString().c_str());
        valid = false;
    }
    // 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 == SH_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/ValidateLimitations.cpp

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