It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/LowerAllocations.cpp b/lib/Transforms/Utils/LowerAllocations.cpp
new file mode 100644
index 0000000..7ce2479
--- /dev/null
+++ b/lib/Transforms/Utils/LowerAllocations.cpp
@@ -0,0 +1,176 @@
+//===- LowerAllocations.cpp - Reduce malloc & free insts to calls ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The LowerAllocations transformation is a target-dependent tranformation
+// because it depends on the size of data types and alignment constraints.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lowerallocs"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Module.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Constants.h"
+#include "llvm/Pass.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+STATISTIC(NumLowered, "Number of allocations lowered");
+
+namespace {
+ /// LowerAllocations - Turn malloc and free instructions into %malloc and
+ /// %free calls.
+ ///
+ class VISIBILITY_HIDDEN LowerAllocations : public BasicBlockPass {
+ Constant *MallocFunc; // Functions in the module we are processing
+ Constant *FreeFunc; // Initialized by doInitialization
+ bool LowerMallocArgToInteger;
+ public:
+ static char ID; // Pass ID, replacement for typeid
+ LowerAllocations(bool LowerToInt = false)
+ : BasicBlockPass((intptr_t)&ID), MallocFunc(0), FreeFunc(0),
+ LowerMallocArgToInteger(LowerToInt) {}
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>();
+ AU.setPreservesCFG();
+
+ // This is a cluster of orthogonal Transforms:
+ AU.addPreserved<UnifyFunctionExitNodes>();
+ AU.addPreservedID(PromoteMemoryToRegisterID);
+ AU.addPreservedID(LowerSelectID);
+ AU.addPreservedID(LowerSwitchID);
+ AU.addPreservedID(LowerInvokePassID);
+ }
+
+ /// doPassInitialization - For the lower allocations pass, this ensures that
+ /// a module contains a declaration for a malloc and a free function.
+ ///
+ bool doInitialization(Module &M);
+
+ virtual bool doInitialization(Function &F) {
+ return BasicBlockPass::doInitialization(F);
+ }
+
+ /// runOnBasicBlock - This method does the actual work of converting
+ /// instructions over, assuming that the pass has already been initialized.
+ ///
+ bool runOnBasicBlock(BasicBlock &BB);
+ };
+
+ char LowerAllocations::ID = 0;
+ RegisterPass<LowerAllocations>
+ X("lowerallocs", "Lower allocations from instructions to calls");
+}
+
+// Publically exposed interface to pass...
+const PassInfo *llvm::LowerAllocationsID = X.getPassInfo();
+// createLowerAllocationsPass - Interface to this file...
+Pass *llvm::createLowerAllocationsPass(bool LowerMallocArgToInteger) {
+ return new LowerAllocations(LowerMallocArgToInteger);
+}
+
+
+// doInitialization - For the lower allocations pass, this ensures that a
+// module contains a declaration for a malloc and a free function.
+//
+// This function is always successful.
+//
+bool LowerAllocations::doInitialization(Module &M) {
+ const Type *BPTy = PointerType::get(Type::Int8Ty);
+ // Prototype malloc as "char* malloc(...)", because we don't know in
+ // doInitialization whether size_t is int or long.
+ FunctionType *FT = FunctionType::get(BPTy, std::vector<const Type*>(), true);
+ MallocFunc = M.getOrInsertFunction("malloc", FT);
+ FreeFunc = M.getOrInsertFunction("free" , Type::VoidTy, BPTy, (Type *)0);
+ return true;
+}
+
+// runOnBasicBlock - This method does the actual work of converting
+// instructions over, assuming that the pass has already been initialized.
+//
+bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
+ bool Changed = false;
+ assert(MallocFunc && FreeFunc && "Pass not initialized!");
+
+ BasicBlock::InstListType &BBIL = BB.getInstList();
+
+ const TargetData &TD = getAnalysis<TargetData>();
+ const Type *IntPtrTy = TD.getIntPtrType();
+
+ // Loop over all of the instructions, looking for malloc or free instructions
+ for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
+ if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
+ const Type *AllocTy = MI->getType()->getElementType();
+
+ // malloc(type) becomes sbyte *malloc(size)
+ Value *MallocArg;
+ if (LowerMallocArgToInteger)
+ MallocArg = ConstantInt::get(Type::Int64Ty, TD.getTypeSize(AllocTy));
+ else
+ MallocArg = ConstantExpr::getSizeOf(AllocTy);
+ MallocArg = ConstantExpr::getTruncOrBitCast(cast<Constant>(MallocArg),
+ IntPtrTy);
+
+ if (MI->isArrayAllocation()) {
+ if (isa<ConstantInt>(MallocArg) &&
+ cast<ConstantInt>(MallocArg)->isOne()) {
+ MallocArg = MI->getOperand(0); // Operand * 1 = Operand
+ } else if (Constant *CO = dyn_cast<Constant>(MI->getOperand(0))) {
+ CO = ConstantExpr::getIntegerCast(CO, IntPtrTy, false /*ZExt*/);
+ MallocArg = ConstantExpr::getMul(CO, cast<Constant>(MallocArg));
+ } else {
+ Value *Scale = MI->getOperand(0);
+ if (Scale->getType() != IntPtrTy)
+ Scale = CastInst::createIntegerCast(Scale, IntPtrTy, false /*ZExt*/,
+ "", I);
+
+ // Multiply it by the array size if necessary...
+ MallocArg = BinaryOperator::create(Instruction::Mul, Scale,
+ MallocArg, "", I);
+ }
+ }
+
+ // Create the call to Malloc.
+ CallInst *MCall = new CallInst(MallocFunc, MallocArg, "", I);
+ MCall->setTailCall();
+
+ // Create a cast instruction to convert to the right type...
+ Value *MCast;
+ if (MCall->getType() != Type::VoidTy)
+ MCast = new BitCastInst(MCall, MI->getType(), "", I);
+ else
+ MCast = Constant::getNullValue(MI->getType());
+
+ // Replace all uses of the old malloc inst with the cast inst
+ MI->replaceAllUsesWith(MCast);
+ I = --BBIL.erase(I); // remove and delete the malloc instr...
+ Changed = true;
+ ++NumLowered;
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(I)) {
+ Value *PtrCast = new BitCastInst(FI->getOperand(0),
+ PointerType::get(Type::Int8Ty), "", I);
+
+ // Insert a call to the free function...
+ (new CallInst(FreeFunc, PtrCast, "", I))->setTailCall();
+
+ // Delete the old free instruction
+ I = --BBIL.erase(I);
+ Changed = true;
+ ++NumLowered;
+ }
+ }
+
+ return Changed;
+}
+