diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/HoistPHIConstants.cpp | 61 | ||||
| -rw-r--r-- | lib/Transforms/Utils/LowerAllocations.cpp | 121 |
2 files changed, 182 insertions, 0 deletions
diff --git a/lib/Transforms/HoistPHIConstants.cpp b/lib/Transforms/HoistPHIConstants.cpp new file mode 100644 index 0000000000..de806fc409 --- /dev/null +++ b/lib/Transforms/HoistPHIConstants.cpp @@ -0,0 +1,61 @@ +//===- llvm/Transforms/HoistPHIConstants.h - Normalize PHI nodes ------------=// +// +// HoistPHIConstants - Remove literal constants that are arguments of PHI nodes +// by inserting cast instructions in the preceeding basic blocks, and changing +// constant references into references of the casted value. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/HoistPHIConstants.h" +#include "llvm/iOther.h" +#include "llvm/BasicBlock.h" +#include "llvm/Method.h" +#include <map> + +typedef pair<BasicBlock *, Value*> BBConstTy; +typedef map<BBConstTy, CastInst *> CachedCopyMap; + +static Value *NormalizePhiOperand(PHINode *PN, Value *CPV, + BasicBlock *Pred, CachedCopyMap &CopyCache) { + + // Check if we've already inserted a copy for this constant in Pred + // Note that `copyCache[Pred]' will create an empty vector the first time + // + CachedCopyMap::iterator CCI = CopyCache.find(BBConstTy(Pred, CPV)); + if (CCI != CopyCache.end()) return CCI->second; + + // Create a copy instruction and add it to the cache... + CastInst *Inst = new CastInst(CPV, CPV->getType()); + CopyCache.insert(make_pair(BBConstTy(Pred, CPV), Inst)); + + // Insert the copy just before the terminator inst of the predecessor BB + assert(Pred->getTerminator() && "Degenerate BB encountered!"); + Pred->getInstList().insert(Pred->getInstList().end()-1, Inst); + + return Inst; +} + + +//--------------------------------------------------------------------------- +// Entry point for normalizing constant args in PHIs +//--------------------------------------------------------------------------- + +bool HoistPHIConstants::doPerMethodWork(Method *M) { + CachedCopyMap Cache; + + for (Method::iterator BI = M->begin(), BE = M->end(); BI != BE; ++BI) + for (BasicBlock::iterator II = (*BI)->begin(); II != (*BI)->end(); ++II) { + Instruction *Inst = *II; + if (!isa<PHINode>(Inst)) break; // All PHIs occur at top of BB! + + PHINode *PN = cast<PHINode>(Inst); + for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i) { + Value *Op = PN->getIncomingValue(i); + if (isa<ConstPoolVal>(Op)) + PN->setIncomingValue(i, + NormalizePhiOperand(PN, Op, PN->getIncomingBlock(i), Cache)); + } + } + + return false; +} diff --git a/lib/Transforms/Utils/LowerAllocations.cpp b/lib/Transforms/Utils/LowerAllocations.cpp new file mode 100644 index 0000000000..ba78ce18fd --- /dev/null +++ b/lib/Transforms/Utils/LowerAllocations.cpp @@ -0,0 +1,121 @@ +//===- llvm/Transforms/LowerAllocations.h - Remove Malloc & Free Insts ------=// +// +// This file implements a pass that lowers malloc and free instructions to +// calls to %malloc & %free functions. This transformation is a target +// dependant tranformation because we depend on the size of data types and +// alignment constraints. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/LowerAllocations.h" +#include "llvm/Target/TargetData.h" +#include "llvm/DerivedTypes.h" +#include "llvm/iMemory.h" +#include "llvm/iOther.h" +#include "llvm/SymbolTable.h" + +// doPassInitialization - 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::doPassInitializationVirt(Module *M) { + const MethodType *MallocType = + MethodType::get(PointerType::get(Type::UByteTy), + vector<const Type*>(1, Type::UIntTy), false); + + SymbolTable *SymTab = M->getSymbolTableSure(); + + // Check for a definition of malloc + if (Value *V = SymTab->lookup(PointerType::get(MallocType), "malloc")) { + MallocMeth = cast<Method>(V); // Yup, got it + } else { // Nope, add one + M->getMethodList().push_back(MallocMeth = new Method(MallocType, "malloc")); + } + + const MethodType *FreeType = + MethodType::get(Type::VoidTy, + vector<const Type*>(1, PointerType::get(Type::UByteTy)), + false); + + // Check for a definition of free + if (Value *V = SymTab->lookup(PointerType::get(FreeType), "free")) { + FreeMeth = cast<Method>(V); // Yup, got it + } else { // Nope, add one + M->getMethodList().push_back(FreeMeth = new Method(FreeType, "free")); + } + + return false; // Always successful +} + +// doPerMethodWork - This method does the actual work of converting +// instructions over, assuming that the pass has already been initialized. +// +bool LowerAllocations::doPerMethodWorkVirt(Method *M) { + assert(MallocMeth && FreeMeth && M && "Pass not initialized!"); + + // Loop over all of the instructions, looking for malloc or free instructions + for (Method::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) { + BasicBlock *BB = *BBI; + for (unsigned i = 0; i < BB->size(); ++i) { + BasicBlock::InstListType &BBIL = BB->getInstList(); + if (MallocInst *MI = dyn_cast<MallocInst>(*(BBIL.begin()+i))) { + BBIL.remove(BBIL.begin()+i); // remove the malloc instr... + + const Type *AllocTy = cast<PointerType>(MI->getType())->getValueType(); + + // If the user is allocating an unsized array with a dynamic size arg, + // start by getting the size of one element. + // + if (const ArrayType *ATy = dyn_cast<ArrayType>(AllocTy)) + if (ATy->isUnsized()) AllocTy = ATy->getElementType(); + + // Get the number of bytes to be allocated for one element of the + // requested type... + unsigned Size = DataLayout.getTypeSize(AllocTy); + + // malloc(type) becomes sbyte *malloc(constint) + Value *MallocArg = ConstPoolUInt::get(Type::UIntTy, Size); + if (MI->getNumOperands() && Size == 1) { + MallocArg = MI->getOperand(0); // Operand * 1 = Operand + } else if (MI->getNumOperands()) { + // Multiply it by the array size if neccesary... + MallocArg = BinaryOperator::create(Instruction::Mul,MI->getOperand(0), + MallocArg); + BBIL.insert(BBIL.begin()+i++, cast<Instruction>(MallocArg)); + } + + // Create the call to Malloc... + CallInst *MCall = new CallInst(MallocMeth, + vector<Value*>(1, MallocArg)); + BBIL.insert(BBIL.begin()+i, MCall); + + // Create a cast instruction to convert to the right type... + CastInst *MCast = new CastInst(MCall, MI->getType()); + BBIL.insert(BBIL.begin()+i+1, MCast); + + // Replace all uses of the old malloc inst with the cast inst + MI->replaceAllUsesWith(MCast); + delete MI; // Delete the malloc inst + } else if (FreeInst *FI = dyn_cast<FreeInst>(*(BBIL.begin()+i))) { + BBIL.remove(BB->getInstList().begin()+i); + + // Cast the argument to free into a ubyte*... + CastInst *MCast = new CastInst(FI->getOperand(0), + PointerType::get(Type::UByteTy)); + BBIL.insert(BBIL.begin()+i, MCast); + + // Insert a call to the free function... + CallInst *FCall = new CallInst(FreeMeth, + vector<Value*>(1, MCast)); + BBIL.insert(BBIL.begin()+i+1, FCall); + + // Delete the old free instruction + delete FI; + } + } + } + + return false; // Always successful +} + |