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.h b/src/compiler/ValidateLimitations.h
new file mode 100644
index 0000000..a4f5a28
--- /dev/null
+++ b/src/compiler/ValidateLimitations.h
@@ -0,0 +1,62 @@
+//
+// Copyright (c) 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 "GLSLANG/ShaderLang.h"
+#include "compiler/intermediate.h"
+
+class TInfoSinkBase;
+
+struct TLoopInfo {
+    struct TIndex {
+        int id;  // symbol id.
+    } index;
+};
+typedef TVector<TLoopInfo> TLoopStack;
+
+// Traverses intermediate tree to ensure that the shader does not exceed the
+// minimum functionality mandated in GLSL 1.0 spec, Appendix A.
+class ValidateLimitations : public TIntermTraverser {
+public:
+    ValidateLimitations(ShShaderType shaderType, TInfoSinkBase& sink);
+
+    int numErrors() const { return mNumErrors; }
+
+    virtual void visitSymbol(TIntermSymbol*);
+    virtual void visitConstantUnion(TIntermConstantUnion*);
+    virtual bool visitBinary(Visit, TIntermBinary*);
+    virtual bool visitUnary(Visit, TIntermUnary*);
+    virtual bool visitSelection(Visit, TIntermSelection*);
+    virtual bool visitAggregate(Visit, TIntermAggregate*);
+    virtual bool visitLoop(Visit, TIntermLoop*);
+    virtual bool visitBranch(Visit, TIntermBranch*);
+
+private:
+    void error(TSourceLoc loc, const char *reason, const char* token);
+
+    bool withinLoopBody() const;
+    bool isLoopIndex(const TIntermSymbol* symbol) const;
+    bool validateLoopType(TIntermLoop* node);
+    bool validateForLoopHeader(TIntermLoop* node, TLoopInfo* info);
+    bool validateForLoopInit(TIntermLoop* node, TLoopInfo* info);
+    bool validateForLoopCond(TIntermLoop* node, TLoopInfo* info);
+    bool validateForLoopExpr(TIntermLoop* node, TLoopInfo* info);
+    // Returns true if none of the loop indices is used as the argument to
+    // the given function out or inout parameter.
+    bool validateFunctionCall(TIntermAggregate* node);
+    bool validateOperation(TIntermOperator* node, TIntermNode* operand);
+
+    // 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);
+
+    ShShaderType mShaderType;
+    TInfoSinkBase& mSink;
+    int mNumErrors;
+    TLoopStack mLoopStack;
+};
+