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rdar://problem/13056109 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180618 91177308-0d34-0410-b5e6-96231b3b80d8
268 lines
11 KiB
C++
268 lines
11 KiB
C++
//===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This family of functions perform various local transformations to the
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// program.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
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#define LLVM_TRANSFORMS_UTILS_LOCAL_H
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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namespace llvm {
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class User;
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class BasicBlock;
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class Function;
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class BranchInst;
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class Instruction;
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class DbgDeclareInst;
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class StoreInst;
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class LoadInst;
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class Value;
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class Pass;
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class PHINode;
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class AllocaInst;
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class ConstantExpr;
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class DataLayout;
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class TargetLibraryInfo;
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class TargetTransformInfo;
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class DIBuilder;
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template<typename T> class SmallVectorImpl;
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//===----------------------------------------------------------------------===//
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// Local constant propagation.
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//
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/// ConstantFoldTerminator - If a terminator instruction is predicated on a
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/// constant value, convert it into an unconditional branch to the constant
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/// destination. This is a nontrivial operation because the successors of this
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/// basic block must have their PHI nodes updated.
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/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
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/// conditions and indirectbr addresses this might make dead if
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/// DeleteDeadConditions is true.
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bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false,
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const TargetLibraryInfo *TLI = 0);
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//===----------------------------------------------------------------------===//
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// Local dead code elimination.
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//
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/// isInstructionTriviallyDead - Return true if the result produced by the
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/// instruction is not used, and the instruction has no side effects.
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///
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bool isInstructionTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=0);
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/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
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/// trivially dead instruction, delete it. If that makes any of its operands
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/// trivially dead, delete them too, recursively. Return true if any
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/// instructions were deleted.
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bool RecursivelyDeleteTriviallyDeadInstructions(Value *V,
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const TargetLibraryInfo *TLI=0);
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/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
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/// dead PHI node, due to being a def-use chain of single-use nodes that
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/// either forms a cycle or is terminated by a trivially dead instruction,
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/// delete it. If that makes any of its operands trivially dead, delete them
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/// too, recursively. Return true if a change was made.
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bool RecursivelyDeleteDeadPHINode(PHINode *PN, const TargetLibraryInfo *TLI=0);
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/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
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/// simplify any instructions in it and recursively delete dead instructions.
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///
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/// This returns true if it changed the code, note that it can delete
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/// instructions in other blocks as well in this block.
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bool SimplifyInstructionsInBlock(BasicBlock *BB, const DataLayout *TD = 0,
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const TargetLibraryInfo *TLI = 0);
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//===----------------------------------------------------------------------===//
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// Control Flow Graph Restructuring.
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//
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/// RemovePredecessorAndSimplify - Like BasicBlock::removePredecessor, this
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/// method is called when we're about to delete Pred as a predecessor of BB. If
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/// BB contains any PHI nodes, this drops the entries in the PHI nodes for Pred.
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///
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/// Unlike the removePredecessor method, this attempts to simplify uses of PHI
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/// nodes that collapse into identity values. For example, if we have:
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/// x = phi(1, 0, 0, 0)
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/// y = and x, z
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///
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/// .. and delete the predecessor corresponding to the '1', this will attempt to
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/// recursively fold the 'and' to 0.
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void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
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DataLayout *TD = 0);
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/// MergeBasicBlockIntoOnlyPred - BB is a block with one predecessor and its
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/// predecessor is known to have one successor (BB!). Eliminate the edge
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/// between them, moving the instructions in the predecessor into BB. This
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/// deletes the predecessor block.
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///
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void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, Pass *P = 0);
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/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
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/// unconditional branch, and contains no instructions other than PHI nodes,
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/// potential debug intrinsics and the branch. If possible, eliminate BB by
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/// rewriting all the predecessors to branch to the successor block and return
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/// true. If we can't transform, return false.
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bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB);
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/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
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/// nodes in this block. This doesn't try to be clever about PHI nodes
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/// which differ only in the order of the incoming values, but instcombine
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/// orders them so it usually won't matter.
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///
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bool EliminateDuplicatePHINodes(BasicBlock *BB);
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/// SimplifyCFG - This function is used to do simplification of a CFG. For
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/// example, it adjusts branches to branches to eliminate the extra hop, it
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/// eliminates unreachable basic blocks, and does other "peephole" optimization
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/// of the CFG. It returns true if a modification was made, possibly deleting
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/// the basic block that was pointed to.
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///
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bool SimplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI,
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const DataLayout *TD = 0);
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/// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
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/// and if a predecessor branches to us and one of our successors, fold the
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/// setcc into the predecessor and use logical operations to pick the right
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/// destination.
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bool FoldBranchToCommonDest(BranchInst *BI);
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/// DemoteRegToStack - This function takes a virtual register computed by an
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/// Instruction and replaces it with a slot in the stack frame, allocated via
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/// alloca. This allows the CFG to be changed around without fear of
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/// invalidating the SSA information for the value. It returns the pointer to
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/// the alloca inserted to create a stack slot for X.
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///
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AllocaInst *DemoteRegToStack(Instruction &X,
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bool VolatileLoads = false,
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Instruction *AllocaPoint = 0);
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/// DemotePHIToStack - This function takes a virtual register computed by a phi
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/// node and replaces it with a slot in the stack frame, allocated via alloca.
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/// The phi node is deleted and it returns the pointer to the alloca inserted.
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AllocaInst *DemotePHIToStack(PHINode *P, Instruction *AllocaPoint = 0);
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/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
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/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
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/// and it is more than the alignment of the ultimate object, see if we can
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/// increase the alignment of the ultimate object, making this check succeed.
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unsigned getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
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const DataLayout *TD = 0);
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/// getKnownAlignment - Try to infer an alignment for the specified pointer.
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static inline unsigned getKnownAlignment(Value *V, const DataLayout *TD = 0) {
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return getOrEnforceKnownAlignment(V, 0, TD);
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}
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/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
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/// code necessary to compute the offset from the base pointer (without adding
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/// in the base pointer). Return the result as a signed integer of intptr size.
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/// When NoAssumptions is true, no assumptions about index computation not
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/// overflowing is made.
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template<typename IRBuilderTy>
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Value *EmitGEPOffset(IRBuilderTy *Builder, const DataLayout &TD, User *GEP,
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bool NoAssumptions = false) {
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gep_type_iterator GTI = gep_type_begin(GEP);
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Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
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Value *Result = Constant::getNullValue(IntPtrTy);
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// If the GEP is inbounds, we know that none of the addressing operations will
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// overflow in an unsigned sense.
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bool isInBounds = cast<GEPOperator>(GEP)->isInBounds() && !NoAssumptions;
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// Build a mask for high order bits.
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unsigned IntPtrWidth = TD.getPointerSizeInBits();
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uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
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for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
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++i, ++GTI) {
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Value *Op = *i;
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uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
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if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
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if (OpC->isZero()) continue;
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// Handle a struct index, which adds its field offset to the pointer.
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if (StructType *STy = dyn_cast<StructType>(*GTI)) {
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Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
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if (Size)
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Result = Builder->CreateAdd(Result, ConstantInt::get(IntPtrTy, Size),
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GEP->getName()+".offs");
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continue;
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}
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Constant *Scale = ConstantInt::get(IntPtrTy, Size);
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Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
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Scale = ConstantExpr::getMul(OC, Scale, isInBounds/*NUW*/);
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// Emit an add instruction.
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Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
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continue;
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}
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// Convert to correct type.
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if (Op->getType() != IntPtrTy)
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Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
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if (Size != 1) {
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// We'll let instcombine(mul) convert this to a shl if possible.
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Op = Builder->CreateMul(Op, ConstantInt::get(IntPtrTy, Size),
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GEP->getName()+".idx", isInBounds /*NUW*/);
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}
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// Emit an add instruction.
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Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
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}
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return Result;
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}
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///===---------------------------------------------------------------------===//
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/// Dbg Intrinsic utilities
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///
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/// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
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/// that has an associated llvm.dbg.decl intrinsic.
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bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
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StoreInst *SI, DIBuilder &Builder);
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/// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
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/// that has an associated llvm.dbg.decl intrinsic.
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bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
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LoadInst *LI, DIBuilder &Builder);
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/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
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/// of llvm.dbg.value intrinsics.
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bool LowerDbgDeclare(Function &F);
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/// FindAllocaDbgDeclare - Finds the llvm.dbg.declare intrinsic corresponding to
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/// an alloca, if any.
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DbgDeclareInst *FindAllocaDbgDeclare(Value *V);
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/// replaceDbgDeclareForAlloca - Replaces llvm.dbg.declare instruction when
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/// alloca is replaced with a new value.
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bool replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
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DIBuilder &Builder);
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/// \brief Remove all blocks that can not be reached from the function's entry.
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///
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/// Returns true if any basic block was removed.
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bool removeUnreachableBlocks(Function &F);
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} // End llvm namespace
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#endif
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