commit ea78d2bb7a07660301ed407d4618f008b9f4395f
author Olli Etuaho <oetuaho@nvidia.com> Tue Jan 09 12:55:27 2018 +0200
committer Commit Bot <commit-bot@chromium.org> Wed Jan 10 21:19:08 2018 +0000
tree 15da3ca2a90b0f87c4aeb708eb0e78086185bdc6
parent 0e1224c82c67aa9a85b571aa41af20ec16dc3911

Prune unreferenced variables with a constructor initializer

Treat aggregate constructors as having no side effects, which enables
pruning declarators that have a constructor initializer.

Some logic in RemoveUnreferencedVariables is fixed to make this work
correctly for structs. The bugs were previously not exposed since
constructors were treated as having side effects, but now that those
can be pruned the logic needs to be correct.

BUG=angleproject:2298
TEST=angle_unittests

Change-Id: I6fbe61a9e82065196baa29c200bf556fc21d8962
Reviewed-on: https://chromium-review.googlesource.com/856499
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

src/compiler/translator/RemoveUnreferencedVariables.cpp

diff --git a/src/compiler/translator/RemoveUnreferencedVariables.cpp b/src/compiler/translator/RemoveUnreferencedVariables.cpp
index e281256..fac73f1 100644
--- a/src/compiler/translator/RemoveUnreferencedVariables.cpp
+++ b/src/compiler/translator/RemoveUnreferencedVariables.cpp
@@ -177,7 +177,17 @@
     if (declarator->getType().isStructSpecifier() && !declarator->getType().isNamelessStruct())
     {
         unsigned int structId = declarator->getType().getStruct()->uniqueId().get();
-        if ((*mStructIdRefCounts)[structId] > 1u)
+        unsigned int structRefCountInThisDeclarator = 1u;
+        if (declarator->getAsBinaryNode() &&
+            declarator->getAsBinaryNode()->getRight()->getAsAggregate())
+        {
+            ASSERT(declarator->getAsBinaryNode()->getLeft()->getType().getStruct() ==
+                   declarator->getType().getStruct());
+            ASSERT(declarator->getAsBinaryNode()->getRight()->getType().getStruct() ==
+                   declarator->getType().getStruct());
+            structRefCountInThisDeclarator = 2u;
+        }
+        if ((*mStructIdRefCounts)[structId] > structRefCountInThisDeclarator)
         {
             // If this declaration declares a named struct type that is used elsewhere, we need to
             // keep it. We can still change the declarator though so that it doesn't declare an
@@ -272,7 +282,7 @@
 
 bool RemoveUnreferencedVariablesTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
 {
-    if (mRemoveReferences)
+    if (visit == PreVisit && mRemoveReferences)
     {
         decrementStructTypeRefCount(node->getType());
     }