Eliminate unused allocas.

src/Reactor/Optimizer.cpp

+// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "Optimizer.hpp"
+
+#include "src/IceCfg.h"
+#include "src/IceCfgNode.h"
+
+#include <map>
+#include <vector>
+
+namespace
+{
+	class Optimizer
+	{
+	public:
+		void run(Ice::Cfg *function);
+
+	private:
+		void analyzeUses(Ice::Cfg *function);
+		void eliminateUnusedAllocas();
+
+		Ice::Cfg *function;
+
+		std::map<Ice::Operand*, std::vector<Ice::Inst*>> uses;
+	};
+
+	void Optimizer::run(Ice::Cfg *function)
+	{
+		this->function = function;
+
+		analyzeUses(function);
+
+		eliminateUnusedAllocas();
+	}
+
+	void Optimizer::eliminateUnusedAllocas()
+	{
+		Ice::CfgNode *entryBlock = function->getEntryNode();
+
+		for(Ice::Inst &alloca : entryBlock->getInsts())
+		{
+			if(!llvm::isa<Ice::InstAlloca>(alloca))
+			{
+				return;   // Allocas are all at the top
+			}
+
+			Ice::Operand *address = alloca.getDest();
+
+			if(uses[address].empty())
+			{
+				alloca.setDeleted();
+			}
+		}
+	}
+
+	void Optimizer::analyzeUses(Ice::Cfg *function)
+	{
+		uses.clear();
+
+		for(Ice::CfgNode *basicBlock : function->getNodes())
+		{
+			for(Ice::Inst &instruction : basicBlock->getInsts())
+			{
+				if(instruction.isDeleted())
+				{
+					continue;
+				}
+
+				for(int i = 0; i < instruction.getSrcSize(); i++)
+				{
+					int unique = 0;
+					for(; unique < i; unique++)
+					{
+						if(instruction.getSrc(i) == instruction.getSrc(unique))
+						{
+							break;
+						}
+					}
+
+					if(i == unique)
+					{
+						uses[instruction.getSrc(i)].push_back(&instruction);
+					}
+				}
+			}
+		}
+	}
+}
+
+namespace sw
+{
+	void optimize(Ice::Cfg *function)
+	{
+		Optimizer optimizer;
+
+		optimizer.run(function);
+	}
+}
\ No newline at end of file

src/Reactor/Optimizer.hpp

+// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef sw_Optimizer_hpp
+#define sw_Optimizer_hpp
+
+#include "src/IceCfg.h"
+
+namespace sw
+{
+	void optimize(Ice::Cfg *function);
+}
+
+#endif   // sw_Optimizer_hpp

src/Reactor/Subzero.vcxproj

@@ -204,6 +204,7 @@
     <ClCompile Include="$(SolutionDir)third_party\pnacl-subzero\src\IceTimerTree.cpp" />
     <ClCompile Include="$(SolutionDir)third_party\pnacl-subzero\src\IceTypes.cpp" />
     <ClCompile Include="$(SolutionDir)third_party\pnacl-subzero\src\IceVariableSplitting.cpp" />
+    <ClCompile Include="Optimizer.cpp" />
     <ClCompile Include="Routine.cpp" />
     <ClCompile Include="SubzeroReactor.cpp" />
   </ItemGroup>
@@ -264,6 +265,7 @@
     <ClInclude Include="$(SolutionDir)third_party\pnacl-subzero\src\IceConditionCodesX8664.h" />
     <ClInclude Include="$(SolutionDir)third_party\pnacl-subzero\src\IceInstX8664.h" />
     <ClInclude Include="$(SolutionDir)third_party\pnacl-subzero\src\IceRegistersX8664.h" />
+    <ClInclude Include="Optimizer.hpp" />
   </ItemGroup>
   <ItemGroup>
     <None Include="$(SolutionDir)third_party\pnacl-subzero\src\IceClFlags.def" />

src/Reactor/Subzero.vcxproj.filters

@@ -117,6 +117,9 @@
     <ClCompile Include="$(SolutionDir)third_party\pnacl-subzero\src\IceTargetLoweringX8664.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="Optimizer.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="$(SolutionDir)third_party\pnacl-subzero\src\IceAssembler.h">
@@ -287,6 +290,9 @@
     <ClInclude Include="$(SolutionDir)third_party\pnacl-subzero\src\IceRegistersX8664.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="Optimizer.hpp">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="$(SolutionDir)third_party\pnacl-subzero\src\IceClFlags.def">

src/Reactor/SubzeroReactor.cpp

@@ -17,6 +17,8 @@
 #include "Reactor.hpp"
 #include "Routine.hpp"
 
+#include "Optimizer.hpp"
+
 #include "src/IceTypes.h"
 #include "src/IceCfg.h"
 #include "src/IceELFStreamer.h"
@@ -422,6 +424,8 @@ namespace sw
 		std::string asciiName(wideName.begin(), wideName.end());
 		::function->setFunctionName(Ice::GlobalString::createWithString(::context, asciiName));
 
+		optimize();
+
 		::function->translate();
 		assert(!::function->hasError());
 
@@ -449,6 +453,7 @@ namespace sw
 
 	void Nucleus::optimize()
 	{
+		sw::optimize(::function);
 	}
 
 	Value *Nucleus::allocateStackVariable(Type *t, int arraySize)