commit a094a8a981bbb84e3bb7fa2acb6f4ac5f0dc2c3e
author Corentin Wallez <cwallez@chromium.org> Tue Apr 07 11:53:06 2015 -0700
committer Corentin Wallez <cwallez@chromium.org> Wed Apr 08 16:48:45 2015 +0000
tree 67d9171c6a26d46fdd03c6f0eefc343bce3380f1
parent 78b3a8b92150d0c0ea28b015f7baea5188857643

Add a compiler option to prune unused function and prototypes

Also adds a simple unit test checking the pruning

BUG=angleproject:937
BUG=395048

Change-Id: I88440378f66178dcebebcd596f8f80235903f20e
Reviewed-on: https://chromium-review.googlesource.com/264568
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>

src/compiler/translator/Compiler.cpp

diff --git a/src/compiler/translator/Compiler.cpp b/src/compiler/translator/Compiler.cpp
index 8c5e50f..ad3dfc5 100644
--- a/src/compiler/translator/Compiler.cpp
+++ b/src/compiler/translator/Compiler.cpp
@@ -246,6 +246,9 @@
             success = tagUsedFunctions();
         }
 
+        if (success && !(compileOptions & SH_DONT_PRUNE_UNUSED_FUNCTIONS))
+            success = pruneUnusedFunctions(root);
+
         if (success && shaderVersion == 300 && shaderType == GL_FRAGMENT_SHADER)
             success = validateOutputs(root);
 
@@ -572,6 +575,59 @@
     }
 }
 
+// A predicate for the stl that returns if a top-level node is unused
+class TCompiler::UnusedPredicate
+{
+  public:
+    UnusedPredicate(const CallDAG *callDag, const std::vector<FunctionMetadata> *metadatas)
+        : mCallDag(callDag),
+          mMetadatas(metadatas)
+    {
+    }
+
+    bool operator ()(TIntermNode *node)
+    {
+        const TIntermAggregate *asAggregate = node->getAsAggregate();
+
+        if (asAggregate == nullptr)
+        {
+            return false;
+        }
+
+        if (!(asAggregate->getOp() == EOpFunction || asAggregate->getOp() == EOpPrototype))
+        {
+            return false;
+        }
+
+        size_t callDagIndex = mCallDag->findIndex(asAggregate);
+        if (callDagIndex == CallDAG::InvalidIndex)
+        {
+            // This happens only for unimplemented prototypes which are thus unused
+            ASSERT(asAggregate->getOp() == EOpPrototype);
+            return true;
+        }
+
+        ASSERT(callDagIndex < mMetadatas->size());
+        return !(*mMetadatas)[callDagIndex].used;
+    }
+
+  private:
+    const CallDAG *mCallDag;
+    const std::vector<FunctionMetadata> *mMetadatas;
+};
+
+bool TCompiler::pruneUnusedFunctions(TIntermNode *root)
+{
+    TIntermAggregate *rootNode = root->getAsAggregate();
+    ASSERT(rootNode != nullptr);
+
+    UnusedPredicate isUnused(&mCallDag, &functionMetadata);
+    TIntermSequence *sequence = rootNode->getSequence();
+    sequence->erase(std::remove_if(sequence->begin(), sequence->end(), isUnused), sequence->end());
+
+    return true;
+}
+
 bool TCompiler::validateOutputs(TIntermNode* root)
 {
     ValidateOutputs validateOutputs(infoSink.info, compileResources.MaxDrawBuffers);