Implement gradient operation AST analysis
This will allow narrowing down which usages of
[[flatten]] and [[unroll]] are actually useful.
BUG=angleproject:937
BUG=395048
Change-Id: Ib8d7b98431b8cd3563e1eff8ecc9ed5df1a9b7d6
Reviewed-on: https://chromium-review.googlesource.com/263775
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/compiler/translator/ASTMetadataHLSL.cpp b/src/compiler/translator/ASTMetadataHLSL.cpp
new file mode 100644
index 0000000..9580667
--- /dev/null
+++ b/src/compiler/translator/ASTMetadataHLSL.cpp
@@ -0,0 +1,181 @@
+//
+// Copyright (c) 2002-2015 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.
+//
+
+// Analysis of the AST needed for HLSL generation
+
+#include "compiler/translator/ASTMetadataHLSL.h"
+
+#include "compiler/translator/CallDAG.h"
+#include "compiler/translator/SymbolTable.h"
+
+namespace
+{
+
+// Class used to traverse the AST of a function definition, checking if the
+// function uses a gradient, and writing the set of control flow using gradients.
+// It assumes that the analysis has already been made for the function's
+// callees.
+class PullGradient : public TIntermTraverser
+{
+ public:
+ PullGradient(MetadataList *metadataList, size_t index, const CallDAG &dag)
+ : TIntermTraverser(true, false, true),
+ mMetadataList(metadataList),
+ mMetadata(&(*metadataList)[index]),
+ mIndex(index),
+ mDag(dag)
+ {
+ ASSERT(index < metadataList->size());
+ }
+
+ void traverse(TIntermAggregate *node)
+ {
+ node->traverse(this);
+ ASSERT(mParents.empty());
+ }
+
+ // Called when a gradient operation or a call to a function using a gradient is found.
+ void onGradient()
+ {
+ mMetadata->mUsesGradient = true;
+ // Mark the latest control flow as using a gradient.
+ if (!mParents.empty())
+ {
+ mMetadata->mControlFlowsContainingGradient.insert(mParents.back());
+ }
+ }
+
+ void visitControlFlow(Visit visit, TIntermNode *node)
+ {
+ if (visit == PreVisit)
+ {
+ mParents.push_back(node);
+ }
+ else if (visit == PostVisit)
+ {
+ ASSERT(mParents.back() == node);
+ mParents.pop_back();
+ // A control flow's using a gradient means its parents are too.
+ if (mMetadata->mControlFlowsContainingGradient.count(node)> 0 && !mParents.empty())
+ {
+ mMetadata->mControlFlowsContainingGradient.insert(mParents.back());
+ }
+ }
+ }
+
+ bool visitLoop(Visit visit, TIntermLoop *loop)
+ {
+ visitControlFlow(visit, loop);
+ return true;
+ }
+
+ bool visitSelection(Visit visit, TIntermSelection *selection)
+ {
+ visitControlFlow(visit, selection);
+ return true;
+ }
+
+ bool visitUnary(Visit visit, TIntermUnary *node) override
+ {
+ if (visit == PreVisit)
+ {
+ switch (node->getOp())
+ {
+ case EOpDFdx:
+ case EOpDFdy:
+ onGradient();
+ default:
+ break;
+ }
+ }
+
+ return true;
+ }
+
+ bool visitAggregate(Visit visit, TIntermAggregate *node) override
+ {
+ if (visit == PreVisit)
+ {
+ if (node->getOp() == EOpFunctionCall)
+ {
+ if (node->isUserDefined())
+ {
+ size_t calleeIndex = mDag.findIndex(node);
+ ASSERT(calleeIndex != CallDAG::InvalidIndex && calleeIndex < mIndex);
+
+ if ((*mMetadataList)[calleeIndex].mUsesGradient) {
+ onGradient();
+ }
+ }
+ else
+ {
+ TString name = TFunction::unmangleName(node->getName());
+
+ if (name == "texture2D" ||
+ name == "texture2DProj" ||
+ name == "textureCube")
+ {
+ onGradient();
+ }
+ }
+ }
+ }
+
+ return true;
+ }
+
+ private:
+ MetadataList *mMetadataList;
+ ASTMetadataHLSL *mMetadata;
+ size_t mIndex;
+ const CallDAG &mDag;
+
+ // Contains a stack of the control flow nodes that are parents of the node being
+ // currently visited. It is used to mark control flows using a gradient.
+ std::vector<TIntermNode*> mParents;
+};
+
+}
+
+bool ASTMetadataHLSL::hasGradientInCallGraph(TIntermSelection *node)
+{
+ return mControlFlowsContainingGradient.count(node) > 0;
+}
+
+bool ASTMetadataHLSL::hasGradientInCallGraph(TIntermLoop *node)
+{
+ return mControlFlowsContainingGradient.count(node) > 0;
+}
+
+MetadataList CreateASTMetadataHLSL(TIntermNode *root, const CallDAG &callDag)
+{
+ MetadataList metadataList(callDag.size());
+
+ // Compute all the information related to when gradient operations are used.
+ // We want to know for each function and control flow operation if they have
+ // a gradient operation in their call graph (shortened to "using a gradient"
+ // in the rest of the file).
+ //
+ // This computation is logically split in three steps:
+ // 1 - For each function compute if it uses a gradient in its body, ignoring
+ // calls to other user-defined functions.
+ // 2 - For each function determine if it uses a gradient in its call graph,
+ // using the result of step 1 and the CallDAG to know its callees.
+ // 3 - For each control flow statement of each function, check if it uses a
+ // gradient in the function's body, or if it calls a user-defined function that
+ // uses a gradient.
+ //
+ // We take advantage of the call graph being a DAG and instead compute 1, 2 and 3
+ // for leaves first, then going down the tree. This is correct because 1 doesn't
+ // depend on other functions, and 2 and 3 depend only on callees.
+ for (size_t i = 0; i < callDag.size(); i++)
+ {
+ PullGradient pull(&metadataList, i, callDag);
+ pull.traverse(callDag.getRecordFromIndex(i).node);
+ }
+
+ return metadataList;
+}