aboutsummaryrefslogtreecommitdiff
path: root/lib/Transforms/LevelRaise.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Transforms/LevelRaise.cpp')
-rw-r--r--lib/Transforms/LevelRaise.cpp458
1 files changed, 458 insertions, 0 deletions
diff --git a/lib/Transforms/LevelRaise.cpp b/lib/Transforms/LevelRaise.cpp
new file mode 100644
index 0000000000..d36046811c
--- /dev/null
+++ b/lib/Transforms/LevelRaise.cpp
@@ -0,0 +1,458 @@
+//===- LevelRaise.cpp - Code to change LLVM to higher level ---------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the 'raising' part of the LevelChange API. This is
+// useful because, in general, it makes the LLVM code terser and easier to
+// analyze.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "TransformInternals.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
+using namespace llvm;
+
+// StartInst - This enables the -raise-start-inst=foo option to cause the level
+// raising pass to start at instruction "foo", which is immensely useful for
+// debugging!
+//
+static cl::opt<std::string>
+StartInst("raise-start-inst", cl::Hidden, cl::value_desc("inst name"),
+ cl::desc("Start raise pass at the instruction with the specified name"));
+
+static Statistic<>
+NumLoadStorePeepholes("raise", "Number of load/store peepholes");
+
+static Statistic<>
+NumGEPInstFormed("raise", "Number of other getelementptr's formed");
+
+static Statistic<>
+NumExprTreesConv("raise", "Number of expression trees converted");
+
+static Statistic<>
+NumCastOfCast("raise", "Number of cast-of-self removed");
+
+static Statistic<>
+NumDCEorCP("raise", "Number of insts DCEd or constprop'd");
+
+static Statistic<>
+NumVarargCallChanges("raise", "Number of vararg call peepholes");
+
+#define PRINT_PEEPHOLE(ID, NUM, I) \
+ DEBUG(std::cerr << "Inst P/H " << ID << "[" << NUM << "] " << I)
+
+#define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
+#define PRINT_PEEPHOLE2(ID, I1, I2) \
+ do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
+#define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
+ do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
+ PRINT_PEEPHOLE(ID, 2, I3); } while (0)
+#define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \
+ do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
+ PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0)
+
+namespace {
+ struct RPR : public FunctionPass {
+ virtual bool runOnFunction(Function &F);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addRequired<TargetData>();
+ }
+
+ private:
+ bool DoRaisePass(Function &F);
+ bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI);
+ };
+
+ RegisterOpt<RPR> X("raise", "Raise Pointer References");
+}
+
+
+FunctionPass *llvm::createRaisePointerReferencesPass() {
+ return new RPR();
+}
+
+
+// isReinterpretingCast - Return true if the cast instruction specified will
+// cause the operand to be "reinterpreted". A value is reinterpreted if the
+// cast instruction would cause the underlying bits to change.
+//
+static inline bool isReinterpretingCast(const CastInst *CI) {
+ return!CI->getOperand(0)->getType()->isLosslesslyConvertibleTo(CI->getType());
+}
+
+bool RPR::PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
+ Instruction *I = BI;
+ const TargetData &TD = getAnalysis<TargetData>();
+
+ if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ Value *Src = CI->getOperand(0);
+ Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source
+ const Type *DestTy = CI->getType();
+
+ // Peephole optimize the following instruction:
+ // %V2 = cast <ty> %V to <ty>
+ //
+ // Into: <nothing>
+ //
+ if (DestTy == Src->getType()) { // Check for a cast to same type as src!!
+ PRINT_PEEPHOLE1("cast-of-self-ty", *CI);
+ CI->replaceAllUsesWith(Src);
+ if (!Src->hasName() && CI->hasName()) {
+ std::string Name = CI->getName();
+ CI->setName("");
+ Src->setName(Name);
+ }
+
+ // DCE the instruction now, to avoid having the iterative version of DCE
+ // have to worry about it.
+ //
+ BI = BB->getInstList().erase(BI);
+
+ ++NumCastOfCast;
+ return true;
+ }
+
+ // Check to see if it's a cast of an instruction that does not depend on the
+ // specific type of the operands to do it's job.
+ if (!isReinterpretingCast(CI)) {
+ ValueTypeCache ConvertedTypes;
+
+ // Check to see if we can convert the source of the cast to match the
+ // destination type of the cast...
+ //
+ ConvertedTypes[CI] = CI->getType(); // Make sure the cast doesn't change
+ if (ExpressionConvertibleToType(Src, DestTy, ConvertedTypes, TD)) {
+ PRINT_PEEPHOLE3("CAST-SRC-EXPR-CONV:in ", *Src, *CI, *BB->getParent());
+
+ DEBUG(std::cerr << "\nCONVERTING SRC EXPR TYPE:\n");
+ { // ValueMap must be destroyed before function verified!
+ ValueMapCache ValueMap;
+ Value *E = ConvertExpressionToType(Src, DestTy, ValueMap, TD);
+
+ if (Constant *CPV = dyn_cast<Constant>(E))
+ CI->replaceAllUsesWith(CPV);
+
+ PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", *E);
+ DEBUG(std::cerr << "DONE CONVERTING SRC EXPR TYPE: \n"
+ << *BB->getParent());
+ }
+
+ BI = BB->begin(); // Rescan basic block. BI might be invalidated.
+ ++NumExprTreesConv;
+ return true;
+ }
+
+ // Check to see if we can convert the users of the cast value to match the
+ // source type of the cast...
+ //
+ ConvertedTypes.clear();
+ // Make sure the source doesn't change type
+ ConvertedTypes[Src] = Src->getType();
+ if (ValueConvertibleToType(CI, Src->getType(), ConvertedTypes, TD)) {
+ //PRINT_PEEPHOLE3("CAST-DEST-EXPR-CONV:in ", *Src, *CI,
+ // *BB->getParent());
+
+ DEBUG(std::cerr << "\nCONVERTING EXPR TYPE:\n");
+ { // ValueMap must be destroyed before function verified!
+ ValueMapCache ValueMap;
+ ConvertValueToNewType(CI, Src, ValueMap, TD); // This will delete CI!
+ }
+
+ PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", *Src);
+ DEBUG(std::cerr << "DONE CONVERTING EXPR TYPE: \n\n" <<
+ *BB->getParent());
+
+ BI = BB->begin(); // Rescan basic block. BI might be invalidated.
+ ++NumExprTreesConv;
+ return true;
+ }
+ }
+
+ // Check to see if we are casting from a structure pointer to a pointer to
+ // the first element of the structure... to avoid munching other peepholes,
+ // we only let this happen if there are no add uses of the cast.
+ //
+ // Peephole optimize the following instructions:
+ // %t1 = cast {<...>} * %StructPtr to <ty> *
+ //
+ // Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
+ // %t1 = cast <eltype> * %t1 to <ty> *
+ //
+ if (const CompositeType *CTy = getPointedToComposite(Src->getType()))
+ if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
+
+ // Loop over uses of the cast, checking for add instructions. If an add
+ // exists, this is probably a part of a more complex GEP, so we don't
+ // want to mess around with the cast.
+ //
+ bool HasAddUse = false;
+ for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
+ I != E; ++I)
+ if (isa<Instruction>(*I) &&
+ cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
+ HasAddUse = true; break;
+ }
+
+ // If it doesn't have an add use, check to see if the dest type is
+ // losslessly convertible to one of the types in the start of the struct
+ // type.
+ //
+ if (!HasAddUse) {
+ const Type *DestPointedTy = DestPTy->getElementType();
+ unsigned Depth = 1;
+ const CompositeType *CurCTy = CTy;
+ const Type *ElTy = 0;
+
+ // Build the index vector, full of all zeros
+ std::vector<Value*> Indices;
+
+ Indices.push_back(Constant::getNullValue(Type::UIntTy));
+ while (CurCTy && !isa<PointerType>(CurCTy)) {
+ if (const StructType *CurSTy = dyn_cast<StructType>(CurCTy)) {
+ // Check for a zero element struct type... if we have one, bail.
+ if (CurSTy->getNumElements() == 0) break;
+
+ // Grab the first element of the struct type, which must lie at
+ // offset zero in the struct.
+ //
+ ElTy = CurSTy->getElementType(0);
+ } else {
+ ElTy = cast<SequentialType>(CurCTy)->getElementType();
+ }
+
+ // Insert a zero to index through this type...
+ Indices.push_back(Constant::getNullValue(Type::UIntTy));
+
+ // Did we find what we're looking for?
+ if (ElTy->isLosslesslyConvertibleTo(DestPointedTy)) break;
+
+ // Nope, go a level deeper.
+ ++Depth;
+ CurCTy = dyn_cast<CompositeType>(ElTy);
+ ElTy = 0;
+ }
+
+ // Did we find what we were looking for? If so, do the transformation
+ if (ElTy) {
+ PRINT_PEEPHOLE1("cast-for-first:in", *CI);
+
+ std::string Name = CI->getName(); CI->setName("");
+
+ // Insert the new T cast instruction... stealing old T's name
+ GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
+ Name, BI);
+
+ // Make the old cast instruction reference the new GEP instead of
+ // the old src value.
+ //
+ CI->setOperand(0, GEP);
+
+ PRINT_PEEPHOLE2("cast-for-first:out", *GEP, *CI);
+ ++NumGEPInstFormed;
+ return true;
+ }
+ }
+ }
+
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ Value *Val = SI->getOperand(0);
+ Value *Pointer = SI->getPointerOperand();
+
+ // Peephole optimize the following instructions:
+ // %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertible to T2
+ // store <T2> %V, <T2>* %t
+ //
+ // Into:
+ // %t = cast <T2> %V to <T1>
+ // store <T1> %t2, <T1>* %P
+ //
+ // Note: This is not taken care of by expr conversion because there might
+ // not be a cast available for the store to convert the incoming value of.
+ // This code is basically here to make sure that pointers don't have casts
+ // if possible.
+ //
+ if (CastInst *CI = dyn_cast<CastInst>(Pointer))
+ if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
+ if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
+ // convertible types?
+ if (Val->getType()->isLosslesslyConvertibleTo(CSPT->getElementType())) {
+ PRINT_PEEPHOLE3("st-src-cast:in ", *Pointer, *Val, *SI);
+
+ // Insert the new T cast instruction... stealing old T's name
+ std::string Name(CI->getName()); CI->setName("");
+ CastInst *NCI = new CastInst(Val, CSPT->getElementType(),
+ Name, BI);
+
+ // Replace the old store with a new one!
+ ReplaceInstWithInst(BB->getInstList(), BI,
+ SI = new StoreInst(NCI, CastSrc));
+ PRINT_PEEPHOLE3("st-src-cast:out", *NCI, *CastSrc, *SI);
+ ++NumLoadStorePeepholes;
+ return true;
+ }
+
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ Value *Pointer = LI->getOperand(0);
+ const Type *PtrElType =
+ cast<PointerType>(Pointer->getType())->getElementType();
+
+ // Peephole optimize the following instructions:
+ // %Val = cast <T1>* to <T2>* ;; If T1 is losslessly convertible to T2
+ // %t = load <T2>* %P
+ //
+ // Into:
+ // %t = load <T1>* %P
+ // %Val = cast <T1> to <T2>
+ //
+ // Note: This is not taken care of by expr conversion because there might
+ // not be a cast available for the store to convert the incoming value of.
+ // This code is basically here to make sure that pointers don't have casts
+ // if possible.
+ //
+ if (CastInst *CI = dyn_cast<CastInst>(Pointer))
+ if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
+ if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
+ // convertible types?
+ if (PtrElType->isLosslesslyConvertibleTo(CSPT->getElementType())) {
+ PRINT_PEEPHOLE2("load-src-cast:in ", *Pointer, *LI);
+
+ // Create the new load instruction... loading the pre-casted value
+ LoadInst *NewLI = new LoadInst(CastSrc, LI->getName(), BI);
+
+ // Insert the new T cast instruction... stealing old T's name
+ CastInst *NCI = new CastInst(NewLI, LI->getType(), CI->getName());
+
+ // Replace the old store with a new one!
+ ReplaceInstWithInst(BB->getInstList(), BI, NCI);
+ PRINT_PEEPHOLE3("load-src-cast:out", *NCI, *CastSrc, *NewLI);
+ ++NumLoadStorePeepholes;
+ return true;
+ }
+
+ } else if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ // If we have a call with all varargs arguments, convert the call to use the
+ // actual argument types present...
+ //
+ const PointerType *PTy = cast<PointerType>(CI->getCalledValue()->getType());
+ const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+
+ // Is the call to a vararg variable with no real parameters?
+ if (FTy->isVarArg() && FTy->getNumParams() == 0 &&
+ !CI->getCalledFunction()) {
+ // If so, insert a new cast instruction, casting it to a function type
+ // that matches the current arguments...
+ //
+ std::vector<const Type *> Params; // Parameter types...
+ for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
+ Params.push_back(CI->getOperand(i)->getType());
+
+ FunctionType *NewFT = FunctionType::get(FTy->getReturnType(),
+ Params, false);
+ PointerType *NewPFunTy = PointerType::get(NewFT);
+
+ // Create a new cast, inserting it right before the function call...
+ Value *NewCast;
+ Constant *ConstantCallSrc = 0;
+ if (Constant *CS = dyn_cast<Constant>(CI->getCalledValue()))
+ ConstantCallSrc = CS;
+
+ if (ConstantCallSrc)
+ NewCast = ConstantExpr::getCast(ConstantCallSrc, NewPFunTy);
+ else
+ NewCast = new CastInst(CI->getCalledValue(), NewPFunTy,
+ CI->getCalledValue()->getName()+"_c",CI);
+
+ // Create a new call instruction...
+ CallInst *NewCall = new CallInst(NewCast,
+ std::vector<Value*>(CI->op_begin()+1, CI->op_end()));
+ if (CI->isTailCall()) NewCall->setTailCall();
+ NewCall->setCallingConv(CI->getCallingConv());
+ ++BI;
+ ReplaceInstWithInst(CI, NewCall);
+
+ ++NumVarargCallChanges;
+ return true;
+ }
+
+ }
+
+ return false;
+}
+
+
+
+
+bool RPR::DoRaisePass(Function &F) {
+ bool Changed = false;
+ for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
+ for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
+ DEBUG(std::cerr << "LevelRaising: " << *BI);
+ if (dceInstruction(BI) || doConstantPropagation(BI)) {
+ Changed = true;
+ ++NumDCEorCP;
+ DEBUG(std::cerr << "***\t\t^^-- Dead code eliminated!\n");
+ } else if (PeepholeOptimize(BB, BI)) {
+ Changed = true;
+ } else {
+ ++BI;
+ }
+ }
+
+ return Changed;
+}
+
+
+// runOnFunction - Raise a function representation to a higher level.
+bool RPR::runOnFunction(Function &F) {
+ DEBUG(std::cerr << "\n\n\nStarting to work on Function '" << F.getName()
+ << "'\n");
+
+ // Insert casts for all incoming pointer pointer values that are treated as
+ // arrays...
+ //
+ bool Changed = false, LocalChange;
+
+ // If the StartInst option was specified, then Peephole optimize that
+ // instruction first if it occurs in this function.
+ //
+ if (!StartInst.empty()) {
+ for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
+ for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI)
+ if (BI->getName() == StartInst) {
+ bool SavedDebug = DebugFlag; // Save the DEBUG() controlling flag.
+ DebugFlag = true; // Turn on DEBUG's
+ Changed |= PeepholeOptimize(BB, BI);
+ DebugFlag = SavedDebug; // Restore DebugFlag to previous state
+ }
+ }
+
+ do {
+ DEBUG(std::cerr << "Looping: \n" << F);
+
+ // Iterate over the function, refining it, until it converges on a stable
+ // state
+ LocalChange = false;
+ while (DoRaisePass(F)) LocalChange = true;
+ Changed |= LocalChange;
+
+ } while (LocalChange);
+
+ return Changed;
+}
+
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-09-07 09:12:45 +0000