Merge pull request #243 from undingen/boxing_opt

add two passes which remove unnecessary boxing

src/codegen/irgen.cpp

@@ -90,6 +90,11 @@ static void optimizeIR(llvm::Function* f, EffortLevel::EffortLevel effort) {
     fpm.add(new llvm::DataLayoutPass());
 #endif
 
+    if (ENABLE_PYSTON_PASSES) {
+        fpm.add(createRemoveUnnecessaryBoxingPass());
+        fpm.add(createRemoveDuplicateBoxingPass());
+    }
+
     if (ENABLE_INLINING && effort >= EffortLevel::MAXIMAL)
         fpm.add(makeFPInliner(275));
     fpm.add(llvm::createCFGSimplificationPass());

src/codegen/opt/boxing_passes.cpp

+// Copyright (c) 2014 Dropbox, Inc.
+//
+// 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 <unordered_map>
+
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
+
+#include "codegen/opt/util.h"
+#include "core/stats.h"
+#include "runtime/inline/boxing.h"
+
+using namespace llvm;
+
+namespace pyston {
+
+// This pass removes boxInt, boxFloat and boxBools calls where the argument is coming from a corresponding unbox call.
+// E.g. if 5784704 is boxFloat:
+// %5 = call i64 @unboxInt(%"class.pyston::Box"* %0)
+// %7 = call %"class.pyston::Box"* @boxInt(i64 %5)
+// --> %7 will be replaced with %0
+class RemoveUnnecessaryBoxingPass : public FunctionPass {
+private:
+public:
+    static char ID;
+    RemoveUnnecessaryBoxingPass() : FunctionPass(ID) {}
+
+    virtual void getAnalysisUsage(AnalysisUsage& info) const { info.setPreservesCFG(); }
+
+    virtual bool runOnFunction(Function& F) {
+        int num_changed = 0;
+        StatCounter sc_num_unnescessary_boxes("opt_unnescessary_boxes");
+
+        std::unordered_map<CallInst*, CallInst*> dead_boxing_call;
+        for (inst_iterator inst_it = inst_begin(F), _inst_end = inst_end(F); inst_it != _inst_end; ++inst_it) {
+            CallInst* CI = dyn_cast<CallInst>(&*inst_it);
+            if (!CI)
+                continue;
+
+            // We are only interested in boxInt, boxFloat and boxBool calls
+            void* func = getCalledFuncAddr(CI);
+            if (func != boxInt && func != boxFloat && func != boxBool)
+                continue;
+
+            CallInst* CI2 = dyn_cast<CallInst>(CI->getArgOperand(0));
+            if (!CI2)
+                continue;
+
+            // Check if the value passed as argument to the boxing call is coming from the corresponding unbox call
+            void* func2 = getCalledFuncAddr(CI2);
+            if ((func == boxInt && func2 == unboxInt) || (func == boxFloat && func2 == unboxFloat)
+                || (func == boxBool && func2 == unboxBool))
+                dead_boxing_call[CI] = CI2;
+        }
+
+        for (auto&& I : dead_boxing_call) {
+            I.first->replaceAllUsesWith(new BitCastInst(I.second->getArgOperand(0), I.first->getType(), "", I.first));
+            I.first->eraseFromParent();
+            ++num_changed;
+            sc_num_unnescessary_boxes.log();
+        }
+
+        return num_changed > 0;
+    }
+};
+char RemoveUnnecessaryBoxingPass::ID = 0;
+
+FunctionPass* createRemoveUnnecessaryBoxingPass() {
+    return new RemoveUnnecessaryBoxingPass();
+}
+
+// This pass removes duplicate boxing calls inside the same BB.
+// E.g. if 5784704 is boxFloat:
+// %282 = call %"class.pyston::Box"* inttoptr (i64 5784704 to %"class.pyston::Box"* (double)*)(double 0.000000e+00)
+// %290 = call %"class.pyston::Box"* inttoptr (i64 5784704 to %"class.pyston::Box"* (double)*)(double 0.000000e+00)
+// --> %290 will be replaced by %282.
+class RemoveDuplicateBoxingPass : public BasicBlockPass {
+private:
+public:
+    static char ID;
+    RemoveDuplicateBoxingPass() : BasicBlockPass(ID) {}
+
+    virtual void getAnalysisUsage(AnalysisUsage& info) const { info.setPreservesCFG(); }
+
+    virtual bool runOnBasicBlock(BasicBlock& BB) {
+        std::unordered_map<std::pair<void*, Value*>, llvm::SmallVector<CallInst*, 4> > boxing_calls;
+
+        // Find all boxInt, boxFloat and boxBool calls inside this BB and add them into a map,
+        // the maps key is pair of the called function and the passed argument
+        for (Instruction& I : BB) {
+            if (CallInst* CI = dyn_cast<CallInst>(&I)) {
+                void* called_func = getCalledFuncAddr(CI);
+                if (called_func == boxInt || called_func == boxFloat || called_func == boxBool)
+                    boxing_calls[std::make_pair(called_func, CI->getArgOperand(0))].push_back(CI);
+            }
+        }
+
+        StatCounter sc_num_duplicate_boxes("opt_duplicate_boxes");
+        int num_changed = 0;
+
+        // Iterate over over all boxing calls found
+        for (auto&& I : boxing_calls) {
+
+            // Check for duplicate calls
+            if (I.second.size() < 2)
+                continue;
+
+            // Replace the duplicate boxing calls with the first one
+            CallInst* FirstCI = 0;
+            for (CallInst* CI : I.second) {
+                if (FirstCI) {
+                    CI->replaceAllUsesWith(FirstCI);
+                    CI->eraseFromParent();
+                    ++num_changed;
+                    sc_num_duplicate_boxes.log();
+                } else {
+                    FirstCI = CI;
+                }
+            }
+        }
+
+        return num_changed > 0;
+    }
+};
+char RemoveDuplicateBoxingPass::ID = 0;
+
+BasicBlockPass* createRemoveDuplicateBoxingPass() {
+    return new RemoveDuplicateBoxingPass();
+}
+}

src/codegen/opt/passes.h

@@ -16,6 +16,7 @@
 #define PYSTON_CODEGEN_OPT_PASSES_H
 
 namespace llvm {
+class BasicBlockPass;
 class FunctionPass;
 class ImmutablePass;
 }
@@ -25,6 +26,8 @@ llvm::ImmutablePass* createPystonAAPass();
 llvm::FunctionPass* createMallocsNonNullPass();
 llvm::FunctionPass* createConstClassesPass();
 llvm::FunctionPass* createDeadAllocsPass();
+llvm::FunctionPass* createRemoveUnnecessaryBoxingPass();
+llvm::BasicBlockPass* createRemoveDuplicateBoxingPass();
 }
 
 #endif

src/codegen/opt/util.cpp

@@ -14,6 +14,7 @@
 
 #include "codegen/opt/util.h"
 
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instructions.h"
@@ -40,4 +41,13 @@ bool isAllocCall(const llvm::CallInst* CI) {
 
     return isAllocCall(Callee->getName());
 }
+
+void* getCalledFuncAddr(const llvm::CallInst* CI) {
+    if (const llvm::ConstantExpr* CE = llvm::dyn_cast<const llvm::ConstantExpr>(CI->getCalledValue())) {
+        llvm::PointerType* PT = llvm::dyn_cast<llvm::PointerType>(CE->getType());
+        if (CE->isCast() && CE->getOpcode() == llvm::Instruction::IntToPtr && PT)
+            return (void*)llvm::cast<llvm::ConstantInt>(CE->getOperand(0))->getSExtValue();
+    }
+    return 0;
+}
 }

src/codegen/opt/util.h

@@ -26,6 +26,7 @@ namespace pyston {
 
 bool isAllocCall(const llvm::StringRef name);
 bool isAllocCall(const llvm::CallInst* CI);
+void* getCalledFuncAddr(const llvm::CallInst* CI);
 }
 
 #endif