Unroll for-loop if sampler array uses loop index as its index.
If inside a for-loop, sampler array index is the loop index, Mac cg compiler will crash. This CL unroll the loop in such situation. The behavior is:
1) If the for-loop index is a float, we reject the shader.
2) If it is an integer, we unroll the for-loop.
Things that should be done in the future are:
1) Add line number macros.
2) Add a limit to unroll iteration count.
anglebug=94
Review URL: http://codereview.appspot.com/4331048
git-svn-id: https://angleproject.googlecode.com/svn/trunk@606 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/compiler/ForLoopUnroll.cpp b/src/compiler/ForLoopUnroll.cpp
new file mode 100644
index 0000000..d631af4
--- /dev/null
+++ b/src/compiler/ForLoopUnroll.cpp
@@ -0,0 +1,172 @@
+//
+// Copyright (c) 2002-2011 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/ForLoopUnroll.h"
+
+void ForLoopUnroll::FillLoopIndexInfo(TIntermLoop* node, TLoopIndexInfo& info)
+{
+ ASSERT(node->getType() == ELoopFor);
+ ASSERT(node->getUnrollFlag());
+
+ TIntermNode* init = node->getInit();
+ ASSERT(init != NULL);
+ TIntermAggregate* decl = init->getAsAggregate();
+ ASSERT((decl != NULL) && (decl->getOp() == EOpDeclaration));
+ TIntermSequence& declSeq = decl->getSequence();
+ ASSERT(declSeq.size() == 1);
+ TIntermBinary* declInit = declSeq[0]->getAsBinaryNode();
+ ASSERT((declInit != NULL) && (declInit->getOp() == EOpInitialize));
+ TIntermSymbol* symbol = declInit->getLeft()->getAsSymbolNode();
+ ASSERT(symbol != NULL);
+ ASSERT(symbol->getBasicType() == EbtInt);
+
+ info.id = symbol->getId();
+
+ ASSERT(declInit->getRight() != NULL);
+ TIntermConstantUnion* initNode = declInit->getRight()->getAsConstantUnion();
+ ASSERT(initNode != NULL);
+
+ info.initValue = evaluateIntConstant(initNode);
+ info.currentValue = info.initValue;
+
+ TIntermNode* cond = node->getCondition();
+ ASSERT(cond != NULL);
+ TIntermBinary* binOp = cond->getAsBinaryNode();
+ ASSERT(binOp != NULL);
+ ASSERT(binOp->getRight() != NULL);
+ ASSERT(binOp->getRight()->getAsConstantUnion() != NULL);
+
+ info.incrementValue = getLoopIncrement(node);
+ info.stopValue = evaluateIntConstant(
+ binOp->getRight()->getAsConstantUnion());
+ info.op = binOp->getOp();
+}
+
+void ForLoopUnroll::Step()
+{
+ ASSERT(mLoopIndexStack.size() > 0);
+ TLoopIndexInfo& info = mLoopIndexStack[mLoopIndexStack.size() - 1];
+ info.currentValue += info.incrementValue;
+}
+
+bool ForLoopUnroll::SatisfiesLoopCondition()
+{
+ ASSERT(mLoopIndexStack.size() > 0);
+ TLoopIndexInfo& info = mLoopIndexStack[mLoopIndexStack.size() - 1];
+ // Relational operator is one of: > >= < <= == or !=.
+ switch (info.op) {
+ case EOpEqual:
+ return (info.currentValue == info.stopValue);
+ case EOpNotEqual:
+ return (info.currentValue != info.stopValue);
+ case EOpLessThan:
+ return (info.currentValue < info.stopValue);
+ case EOpGreaterThan:
+ return (info.currentValue > info.stopValue);
+ case EOpLessThanEqual:
+ return (info.currentValue <= info.stopValue);
+ case EOpGreaterThanEqual:
+ return (info.currentValue >= info.stopValue);
+ default:
+ UNREACHABLE();
+ }
+ return false;
+}
+
+bool ForLoopUnroll::NeedsToReplaceSymbolWithValue(TIntermSymbol* symbol)
+{
+ for (TVector<TLoopIndexInfo>::iterator i = mLoopIndexStack.begin();
+ i != mLoopIndexStack.end();
+ ++i) {
+ if (i->id == symbol->getId())
+ return true;
+ }
+ return false;
+}
+
+int ForLoopUnroll::GetLoopIndexValue(TIntermSymbol* symbol)
+{
+ for (TVector<TLoopIndexInfo>::iterator i = mLoopIndexStack.begin();
+ i != mLoopIndexStack.end();
+ ++i) {
+ if (i->id == symbol->getId())
+ return i->currentValue;
+ }
+ UNREACHABLE();
+ return false;
+}
+
+void ForLoopUnroll::Push(TLoopIndexInfo& info)
+{
+ mLoopIndexStack.push_back(info);
+}
+
+void ForLoopUnroll::Pop()
+{
+ mLoopIndexStack.pop_back();
+}
+
+int ForLoopUnroll::getLoopIncrement(TIntermLoop* node)
+{
+ TIntermNode* expr = node->getExpression();
+ ASSERT(expr != NULL);
+ // 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;
+ TIntermConstantUnion* incrementNode = NULL;
+ if (unOp != NULL) {
+ op = unOp->getOp();
+ } else if (binOp != NULL) {
+ op = binOp->getOp();
+ ASSERT(binOp->getRight() != NULL);
+ incrementNode = binOp->getRight()->getAsConstantUnion();
+ ASSERT(incrementNode != NULL);
+ }
+
+ int increment = 0;
+ // The operator is one of: ++ -- += -=.
+ switch (op) {
+ case EOpPostIncrement:
+ case EOpPreIncrement:
+ ASSERT((unOp != NULL) && (binOp == NULL));
+ increment = 1;
+ break;
+ case EOpPostDecrement:
+ case EOpPreDecrement:
+ ASSERT((unOp != NULL) && (binOp == NULL));
+ increment = -1;
+ break;
+ case EOpAddAssign:
+ ASSERT((unOp == NULL) && (binOp != NULL));
+ increment = evaluateIntConstant(incrementNode);
+ break;
+ case EOpSubAssign:
+ ASSERT((unOp == NULL) && (binOp != NULL));
+ increment = - evaluateIntConstant(incrementNode);
+ break;
+ default:
+ ASSERT(false);
+ }
+
+ return increment;
+}
+
+int ForLoopUnroll::evaluateIntConstant(TIntermConstantUnion* node)
+{
+ ASSERT((node != NULL) && (node->getUnionArrayPointer() != NULL));
+ return node->getUnionArrayPointer()->getIConst();
+}
+