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237e6d10f2
Remove extraneous #includes of llvm/Assembly/Writer git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2178 91177308-0d34-0410-b5e6-96231b3b80d8
483 lines
17 KiB
C++
483 lines
17 KiB
C++
//===- LevelRaise.cpp - Code to change LLVM to higher level -----------------=//
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//
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// This file implements the 'raising' part of the LevelChange API. This is
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// useful because, in general, it makes the LLVM code terser and easier to
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// analyze.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/LevelChange.h"
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#include "TransformInternals.h"
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#include "llvm/Function.h"
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#include "llvm/iOther.h"
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#include "llvm/iMemory.h"
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#include "llvm/ConstantVals.h"
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#include "llvm/Pass.h"
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#include "llvm/ConstantHandling.h"
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#include "llvm/Transforms/Scalar/DCE.h"
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#include "llvm/Transforms/Scalar/ConstantProp.h"
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#include "llvm/Analysis/Expressions.h"
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#include "Support/STLExtras.h"
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#include <algorithm>
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//#define DEBUG_PEEPHOLE_INSTS 1
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#ifdef DEBUG_PEEPHOLE_INSTS
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#define PRINT_PEEPHOLE(ID, NUM, I) \
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std::cerr << "Inst P/H " << ID << "[" << NUM << "] " << I;
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#else
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#define PRINT_PEEPHOLE(ID, NUM, I)
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#endif
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#define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
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#define PRINT_PEEPHOLE2(ID, I1, I2) \
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do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
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#define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
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do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
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PRINT_PEEPHOLE(ID, 2, I3); } while (0)
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#define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \
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do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
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PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0)
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// isReinterpretingCast - Return true if the cast instruction specified will
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// cause the operand to be "reinterpreted". A value is reinterpreted if the
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// cast instruction would cause the underlying bits to change.
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//
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static inline bool isReinterpretingCast(const CastInst *CI) {
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return!CI->getOperand(0)->getType()->isLosslesslyConvertableTo(CI->getType());
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}
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// Peephole optimize the following instructions:
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// %t1 = cast ? to x *
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// %t2 = add x * %SP, %t1 ;; Constant must be 2nd operand
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//
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// Into: %t3 = getelementptr {<...>} * %SP, <element indices>
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// %t2 = cast <eltype> * %t3 to {<...>}*
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//
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static bool HandleCastToPointer(BasicBlock::iterator BI,
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const PointerType *DestPTy) {
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CastInst *CI = cast<CastInst>(*BI);
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if (CI->use_empty()) return false;
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// Scan all of the uses, looking for any uses that are not add
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// instructions. If we have non-adds, do not make this transformation.
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//
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for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
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I != E; ++I) {
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*I)) {
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if (BO->getOpcode() != Instruction::Add)
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return false;
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} else {
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return false;
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}
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}
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std::vector<Value*> Indices;
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Value *Src = CI->getOperand(0);
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const Type *Result = ConvertableToGEP(DestPTy, Src, Indices, &BI);
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if (Result == 0) return false; // Not convertable...
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PRINT_PEEPHOLE2("cast-add-to-gep:in", Src, CI);
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// If we have a getelementptr capability... transform all of the
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// add instruction uses into getelementptr's.
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while (!CI->use_empty()) {
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BinaryOperator *I = cast<BinaryOperator>(*CI->use_begin());
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assert(I->getOpcode() == Instruction::Add && I->getNumOperands() == 2 &&
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"Use is not a valid add instruction!");
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// Get the value added to the cast result pointer...
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Value *OtherPtr = I->getOperand((I->getOperand(0) == CI) ? 1 : 0);
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Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
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PRINT_PEEPHOLE1("cast-add-to-gep:i", I);
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if (GEP->getType() == I->getType()) {
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// Replace the old add instruction with the shiny new GEP inst
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ReplaceInstWithInst(I, GEP);
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} else {
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// If the type produced by the gep instruction differs from the original
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// add instruction type, insert a cast now.
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//
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// Insert the GEP instruction before the old add instruction... and get an
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// iterator to point at the add instruction...
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BasicBlock::iterator GEPI = InsertInstBeforeInst(GEP, I)+1;
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PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
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CastInst *CI = new CastInst(GEP, I->getType());
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GEP = CI;
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// Replace the old add instruction with the shiny new GEP inst
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ReplaceInstWithInst(I->getParent()->getInstList(), GEPI, GEP);
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}
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PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
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}
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return true;
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}
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// Peephole optimize the following instructions:
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// %t1 = cast ulong <const int> to {<...>} *
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// %t2 = add {<...>} * %SP, %t1 ;; Constant must be 2nd operand
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//
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// or
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// %t1 = cast {<...>}* %SP to int*
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// %t5 = cast ulong <const int> to int*
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// %t2 = add int* %t1, %t5 ;; int is same size as field
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//
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// Into: %t3 = getelementptr {<...>} * %SP, <element indices>
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// %t2 = cast <eltype> * %t3 to {<...>}*
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//
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static bool PeepholeOptimizeAddCast(BasicBlock *BB, BasicBlock::iterator &BI,
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Value *AddOp1, CastInst *AddOp2) {
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const CompositeType *CompTy;
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Value *OffsetVal = AddOp2->getOperand(0);
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Value *SrcPtr; // Of type pointer to struct...
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if ((CompTy = getPointedToComposite(AddOp1->getType()))) {
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SrcPtr = AddOp1; // Handle the first case...
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} else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) {
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SrcPtr = AddOp1c->getOperand(0); // Handle the second case...
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CompTy = getPointedToComposite(SrcPtr->getType());
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}
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// Only proceed if we have detected all of our conditions successfully...
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if (!CompTy || !SrcPtr || !OffsetVal->getType()->isIntegral())
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return false;
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std::vector<Value*> Indices;
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if (!ConvertableToGEP(SrcPtr->getType(), OffsetVal, Indices, &BI))
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return false; // Not convertable... perhaps next time
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if (getPointedToComposite(AddOp1->getType())) { // case 1
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PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, *BI);
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} else {
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PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, *BI);
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}
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GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Indices,
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AddOp2->getName());
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BI = BB->getInstList().insert(BI, GEP)+1;
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Instruction *NCI = new CastInst(GEP, AddOp1->getType());
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ReplaceInstWithInst(BB->getInstList(), BI, NCI);
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PRINT_PEEPHOLE2("add-to-gep:out", GEP, NCI);
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return true;
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}
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static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
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Instruction *I = *BI;
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if (CastInst *CI = dyn_cast<CastInst>(I)) {
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Value *Src = CI->getOperand(0);
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Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source
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const Type *DestTy = CI->getType();
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// Peephole optimize the following instruction:
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// %V2 = cast <ty> %V to <ty>
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//
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// Into: <nothing>
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//
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if (DestTy == Src->getType()) { // Check for a cast to same type as src!!
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PRINT_PEEPHOLE1("cast-of-self-ty", CI);
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CI->replaceAllUsesWith(Src);
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if (!Src->hasName() && CI->hasName()) {
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std::string Name = CI->getName();
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CI->setName("");
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Src->setName(Name, BB->getParent()->getSymbolTable());
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}
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return true;
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}
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// Peephole optimize the following instructions:
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// %tmp = cast <ty> %V to <ty2>
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// %V = cast <ty2> %tmp to <ty3> ; Where ty & ty2 are same size
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//
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// Into: cast <ty> %V to <ty3>
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//
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if (SrcI)
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if (CastInst *CSrc = dyn_cast<CastInst>(SrcI))
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if (isReinterpretingCast(CI) + isReinterpretingCast(CSrc) < 2) {
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// We can only do c-c elimination if, at most, one cast does a
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// reinterpretation of the input data.
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//
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// If legal, make this cast refer the the original casts argument!
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//
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PRINT_PEEPHOLE2("cast-cast:in ", CI, CSrc);
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CI->setOperand(0, CSrc->getOperand(0));
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PRINT_PEEPHOLE1("cast-cast:out", CI);
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return true;
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}
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// Check to see if it's a cast of an instruction that does not depend on the
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// specific type of the operands to do it's job.
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if (!isReinterpretingCast(CI)) {
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ValueTypeCache ConvertedTypes;
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// Check to see if we can convert the users of the cast value to match the
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// source type of the cast...
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//
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ConvertedTypes[CI] = CI->getType(); // Make sure the cast doesn't change
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if (ExpressionConvertableToType(Src, DestTy, ConvertedTypes)) {
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PRINT_PEEPHOLE3("CAST-SRC-EXPR-CONV:in ", Src, CI, BB->getParent());
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "\nCONVERTING SRC EXPR TYPE:\n";
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#endif
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ValueMapCache ValueMap;
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Value *E = ConvertExpressionToType(Src, DestTy, ValueMap);
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if (Constant *CPV = dyn_cast<Constant>(E))
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CI->replaceAllUsesWith(CPV);
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BI = BB->begin(); // Rescan basic block. BI might be invalidated.
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PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", E);
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "DONE CONVERTING SRC EXPR TYPE: \n" << BB->getParent();
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#endif
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return true;
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}
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// Check to see if we can convert the source of the cast to match the
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// destination type of the cast...
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//
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ConvertedTypes.clear();
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if (ValueConvertableToType(CI, Src->getType(), ConvertedTypes)) {
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PRINT_PEEPHOLE3("CAST-DEST-EXPR-CONV:in ", Src, CI, BB->getParent());
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "\nCONVERTING EXPR TYPE:\n";
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#endif
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ValueMapCache ValueMap;
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ConvertValueToNewType(CI, Src, ValueMap); // This will delete CI!
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BI = BB->begin(); // Rescan basic block. BI might be invalidated.
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PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", Src);
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "DONE CONVERTING EXPR TYPE: \n\n" << BB->getParent();
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#endif
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return true;
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}
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}
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// Otherwise find out it this cast is a cast to a pointer type, which is
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// then added to some other pointer, then loaded or stored through. If
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// so, convert the add into a getelementptr instruction...
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//
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if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
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if (HandleCastToPointer(BI, DestPTy)) {
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BI = BB->begin(); // Rescan basic block. BI might be invalidated.
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return true;
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}
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}
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// Check to see if we are casting from a structure pointer to a pointer to
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// the first element of the structure... to avoid munching other peepholes,
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// we only let this happen if there are no add uses of the cast.
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//
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// Peephole optimize the following instructions:
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// %t1 = cast {<...>} * %StructPtr to <ty> *
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//
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// Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
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// %t1 = cast <eltype> * %t1 to <ty> *
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//
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#if 1
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if (const CompositeType *CTy = getPointedToComposite(Src->getType()))
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if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
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// Loop over uses of the cast, checking for add instructions. If an add
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// exists, this is probably a part of a more complex GEP, so we don't
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// want to mess around with the cast.
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//
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bool HasAddUse = false;
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for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
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I != E; ++I)
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if (isa<Instruction>(*I) &&
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cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
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HasAddUse = true; break;
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}
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// If it doesn't have an add use, check to see if the dest type is
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// losslessly convertable to one of the types in the start of the struct
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// type.
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//
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if (!HasAddUse) {
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const Type *DestPointedTy = DestPTy->getElementType();
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unsigned Depth = 1;
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const CompositeType *CurCTy = CTy;
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const Type *ElTy = 0;
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// Build the index vector, full of all zeros
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std::vector<Value*> Indices;
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Indices.push_back(ConstantUInt::get(Type::UIntTy, 0));
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while (CurCTy && !isa<PointerType>(CurCTy)) {
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if (const StructType *CurSTy = dyn_cast<StructType>(CurCTy)) {
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// Check for a zero element struct type... if we have one, bail.
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if (CurSTy->getElementTypes().size() == 0) break;
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// Grab the first element of the struct type, which must lie at
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// offset zero in the struct.
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//
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ElTy = CurSTy->getElementTypes()[0];
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} else {
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ElTy = cast<ArrayType>(CurCTy)->getElementType();
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}
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// Insert a zero to index through this type...
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Indices.push_back(ConstantUInt::get(CurCTy->getIndexType(), 0));
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// Did we find what we're looking for?
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if (ElTy->isLosslesslyConvertableTo(DestPointedTy)) break;
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// Nope, go a level deeper.
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++Depth;
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CurCTy = dyn_cast<CompositeType>(ElTy);
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ElTy = 0;
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}
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// Did we find what we were looking for? If so, do the transformation
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if (ElTy) {
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PRINT_PEEPHOLE1("cast-for-first:in", CI);
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// Insert the new T cast instruction... stealing old T's name
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GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
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CI->getName());
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CI->setName("");
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BI = BB->getInstList().insert(BI, GEP)+1;
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// Make the old cast instruction reference the new GEP instead of
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// the old src value.
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//
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CI->setOperand(0, GEP);
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PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI);
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return true;
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}
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}
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}
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#endif
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#if 1
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} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
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Value *Val = SI->getOperand(0);
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Value *Pointer = SI->getPointerOperand();
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// Peephole optimize the following instructions:
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// %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
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// store <T2> %V, <T2>* %t
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//
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// Into:
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// %t = cast <T2> %V to <T1>
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// store <T1> %t2, <T1>* %P
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//
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// Note: This is not taken care of by expr conversion because there might
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// not be a cast available for the store to convert the incoming value of.
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// This code is basically here to make sure that pointers don't have casts
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// if possible.
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//
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if (CastInst *CI = dyn_cast<CastInst>(Pointer))
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if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
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if (PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
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// convertable types?
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if (Val->getType()->isLosslesslyConvertableTo(CSPT->getElementType()) &&
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!SI->hasIndices()) { // No subscripts yet!
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PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);
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// Insert the new T cast instruction... stealing old T's name
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CastInst *NCI = new CastInst(Val, CSPT->getElementType(),
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CI->getName());
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CI->setName("");
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BI = BB->getInstList().insert(BI, NCI)+1;
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// Replace the old store with a new one!
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ReplaceInstWithInst(BB->getInstList(), BI,
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SI = new StoreInst(NCI, CastSrc));
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PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
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return true;
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}
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} else if (I->getOpcode() == Instruction::Add &&
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isa<CastInst>(I->getOperand(1))) {
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if (PeepholeOptimizeAddCast(BB, BI, I->getOperand(0),
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cast<CastInst>(I->getOperand(1))))
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return true;
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#endif
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}
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return false;
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}
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static bool DoRaisePass(Function *F) {
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bool Changed = false;
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for (Function::iterator MI = F->begin(), ME = F->end(); MI != ME; ++MI) {
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BasicBlock *BB = *MI;
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BasicBlock::InstListType &BIL = BB->getInstList();
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for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
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#if DEBUG_PEEPHOLE_INSTS
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cerr << "Processing: " << *BI;
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#endif
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if (dceInstruction(BIL, BI) || doConstantPropogation(BB, BI)) {
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Changed = true;
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "***\t\t^^-- DeadCode Elinated!\n";
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#endif
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} else if (PeepholeOptimize(BB, BI))
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Changed = true;
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else
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++BI;
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}
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}
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return Changed;
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}
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// RaisePointerReferences::doit - Raise a method representation to a higher
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// level.
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//
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static bool doRPR(Function *F) {
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#ifdef DEBUG_PEEPHOLE_INSTS
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cerr << "\n\n\nStarting to work on Function '" << F->getName() << "'\n";
|
|
#endif
|
|
|
|
// Insert casts for all incoming pointer pointer values that are treated as
|
|
// arrays...
|
|
//
|
|
bool Changed = false, LocalChange;
|
|
|
|
do {
|
|
#ifdef DEBUG_PEEPHOLE_INSTS
|
|
cerr << "Looping: \n" << F;
|
|
#endif
|
|
|
|
// Iterate over the method, refining it, until it converges on a stable
|
|
// state
|
|
LocalChange = false;
|
|
while (DoRaisePass(F)) LocalChange = true;
|
|
Changed |= LocalChange;
|
|
|
|
} while (LocalChange);
|
|
|
|
return Changed;
|
|
}
|
|
|
|
namespace {
|
|
struct RaisePointerReferences : public MethodPass {
|
|
virtual bool runOnMethod(Function *F) { return doRPR(F); }
|
|
};
|
|
}
|
|
|
|
Pass *createRaisePointerReferencesPass() {
|
|
return new RaisePointerReferences();
|
|
}
|
|
|
|
|