Implemented validation for loop and indexing limitations specified by GLSL ES spec 1.0 Appendix A Section 4 and 5.
A couple of things to note:
- This CL only validates the "form" of loop and indexing. It does not detect number-of-iterations or out-of-bound access. This will require more involved analysis/heuristics.
- I haved combined SH_VALIDATE_CONTROL_FLOW and SH_VALIDATE_INDEXING into one flag - SH_VALIDATE_LOOP_INDEXING. Validating both together is much easier.
BUG=48
Review URL: http://codereview.appspot.com/3225041
git-svn-id: https://angleproject.googlecode.com/svn/trunk@491 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/compiler/ValidateLimitations.cpp b/src/compiler/ValidateLimitations.cpp
new file mode 100644
index 0000000..886f693
--- /dev/null
+++ b/src/compiler/ValidateLimitations.cpp
@@ -0,0 +1,468 @@
+//
+// 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/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;
+}
+
+// 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);
+ }
+ }
+ virtual void visitConstantUnion(TIntermConstantUnion*) {}
+ virtual bool visitBinary(Visit, TIntermBinary*) { return true; }
+ virtual bool visitUnary(Visit, TIntermUnary*) { return true; }
+ virtual bool visitSelection(Visit, TIntermSelection*) { return true; }
+ virtual bool visitAggregate(Visit, TIntermAggregate*) { return true; }
+ virtual bool visitLoop(Visit, TIntermLoop*) { return true; }
+ virtual bool visitBranch(Visit, TIntermBranch*) { return true; }
+
+private:
+ bool mValid;
+ const TLoopStack& mLoopStack;
+};
+} // namespace
+
+ValidateLimitations::ValidateLimitations(ShShaderType shaderType,
+ TInfoSinkBase& sink)
+ : mShaderType(shaderType),
+ mSink(sink),
+ mNumErrors(0)
+{
+}
+
+void ValidateLimitations::visitSymbol(TIntermSymbol*)
+{
+}
+
+void ValidateLimitations::visitConstantUnion(TIntermConstantUnion*)
+{
+}
+
+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:
+ 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::visitSelection(Visit, TIntermSelection*)
+{
+ 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));
+ 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;
+}
+
+bool ValidateLimitations::visitBranch(Visit, TIntermBranch*)
+{
+ return true;
+}
+
+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<int> 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;
+}
+