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Revert r257164 - it has caused spec2k6 failures in LTO mode
llvm-svn: 257340
This commit is contained in:
Silviu Baranga
parent
f78b9ea9f0
commit
90360019af
@ -13,7 +13,6 @@
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#include "InstCombineInternal.h"
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#include "llvm/ADT/APSInt.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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@ -596,320 +595,6 @@ static Value *EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC,
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return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset");
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}
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/// Returns true if we can rewrite Start as a GEP with pointer Base
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/// and some integer offset. The nodes that need to be re-written
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/// for this transformation will be added to Explored.
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static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
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const DataLayout &DL,
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SetVector<Value *> &Explored) {
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SmallVector<Value *, 16> WorkList(1, Start);
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Explored.insert(Base);
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// The following traversal gives us an order which can be used
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// when doing the final transformation. Since in the final
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// transformation we create the PHI replacement instructions first,
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// we don't have to get them in any particular order.
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//
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// However, for other instructions we will have to traverse the
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// operands of an instruction first, which means that we have to
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// do a post-order traversal.
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while (!WorkList.empty()) {
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SetVector<PHINode *> PHIs;
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while (!WorkList.empty()) {
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if (Explored.size() >= 100)
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return false;
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Value *V = WorkList.back();
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if (Explored.count(V) != 0) {
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WorkList.pop_back();
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continue;
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}
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if (!isa<IntToPtrInst>(V) && !isa<PtrToIntInst>(V) &&
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!isa<GEPOperator>(V) && !isa<PHINode>(V))
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// We've found some value that we can't explore which is different from
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// the base. Therefore we can't do this transformation.
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return false;
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if (isa<IntToPtrInst>(V) || isa<PtrToIntInst>(V)) {
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auto *CI = dyn_cast<CastInst>(V);
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if (!CI->isNoopCast(DL))
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return false;
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if (Explored.count(CI->getOperand(0)) == 0)
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WorkList.push_back(CI->getOperand(0));
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}
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if (auto *GEP = dyn_cast<GEPOperator>(V)) {
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// We're limiting the GEP to having one index. This will preserve
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// the original pointer type. We could handle more cases in the
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// future.
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if (GEP->getNumIndices() != 1 || !GEP->isInBounds())
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return false;
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if (Explored.count(GEP->getOperand(0)) == 0)
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WorkList.push_back(GEP->getOperand(0));
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}
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if (WorkList.back() == V) {
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WorkList.pop_back();
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// We've finished visiting this node, mark it as such.
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Explored.insert(V);
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}
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if (auto *PN = dyn_cast<PHINode>(V)) {
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Explored.insert(PN);
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PHIs.insert(PN);
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}
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}
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// Explore the PHI nodes further.
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for (auto *PN : PHIs)
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for (Value *Op : PN->incoming_values())
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if (Explored.count(Op) == 0)
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WorkList.push_back(Op);
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}
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// Make sure that we can do this. Since we can't insert GEPs in a basic
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// block before a PHI node, we can't easily do this transformation if
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// we have PHI node users of transformed instructions.
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for (Value *Val : Explored) {
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for (Value *Use : Val->uses()) {
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auto *PHI = dyn_cast<PHINode>(Use);
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auto *Inst = dyn_cast<Instruction>(Val);
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if (Inst == Base || Inst == PHI || !Inst || !PHI ||
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Explored.count(PHI) == 0)
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continue;
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if (PHI->getParent() == Inst->getParent())
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return false;
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}
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}
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return true;
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}
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// Sets the appropriate insert point on Builder where we can add
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// a replacement Instruction for V (if that is possible).
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static void setInsertionPoint(IRBuilder<> &Builder, Value *V,
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bool Before = true) {
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if (auto *PHI = dyn_cast<PHINode>(V)) {
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Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt());
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return;
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}
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if (auto *I = dyn_cast<Instruction>(V)) {
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if (!Before)
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I = &*std::next(I->getIterator());
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Builder.SetInsertPoint(I);
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return;
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}
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if (auto *A = dyn_cast<Argument>(V)) {
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// Set the insertion point in the entry block.
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BasicBlock &Entry = A->getParent()->getEntryBlock();
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Builder.SetInsertPoint(&*Entry.getFirstInsertionPt());
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return;
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}
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// Otherwise, this is a constant and we don't need to set a new
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// insertion point.
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assert(isa<Constant>(V) && "Setting insertion point for unknown value!");
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}
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/// Returns a re-written value of Start as an indexed GEP using Base as a
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/// pointer.
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static Value *rewriteGEPAsOffset(Value *Start, Value *Base,
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const DataLayout &DL,
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SetVector<Value *> &Explored) {
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// Perform all the substitutions. This is a bit tricky because we can
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// have cycles in our use-def chains.
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// 1. Create the PHI nodes without any incoming values.
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// 2. Create all the other values.
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// 3. Add the edges for the PHI nodes.
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// 4. Emit GEPs to get the original pointers.
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// 5. Remove the original instructions.
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Type *IndexType = IntegerType::get(
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Base->getContext(), DL.getPointerTypeSizeInBits(Start->getType()));
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DenseMap<Value *, Value *> NewInsts;
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NewInsts[Base] = ConstantInt::getNullValue(IndexType);
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// Create the new PHI nodes, without adding any incoming values.
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for (Value *Val : Explored) {
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if (Val == Base)
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continue;
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// Create empty phi nodes. This avoids cyclic dependencies when creating
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// the remaining instructions.
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if (auto *PHI = dyn_cast<PHINode>(Val))
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NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(),
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PHI->getName() + ".idx", PHI);
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}
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IRBuilder<> Builder(Base->getContext());
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// Create all the other instructions.
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for (Value *Val : Explored) {
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if (NewInsts.find(Val) != NewInsts.end())
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continue;
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if (auto *CI = dyn_cast<CastInst>(Val)) {
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NewInsts[CI] = NewInsts[CI->getOperand(0)];
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continue;
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}
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if (auto *GEP = dyn_cast<GEPOperator>(Val)) {
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Value *Index = NewInsts[GEP->getOperand(1)]
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? NewInsts[GEP->getOperand(1)]
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: GEP->getOperand(1);
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setInsertionPoint(Builder, GEP);
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// Indices might need to be sign extended. GEPs will magically do
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// this, but we need to do it ourselves here.
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if (Index->getType()->getScalarSizeInBits() !=
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NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) {
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Index = Builder.CreateSExtOrTrunc(
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Index, NewInsts[GEP->getOperand(0)]->getType(),
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GEP->getOperand(0)->getName() + ".sext");
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}
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NewInsts[GEP] =
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Builder.CreateAdd(NewInsts[GEP->getOperand(0)], Index,
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GEP->getOperand(0)->getName() + ".add");
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continue;
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}
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if (isa<PHINode>(Val))
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continue;
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llvm_unreachable("Unexpected instruction type");
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}
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// Add the incoming values to the PHI nodes.
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for (Value *Val : Explored) {
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if (Val == Base)
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continue;
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// All the instructions have been created, we can now add edges to the
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// phi nodes.
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if (auto *PHI = dyn_cast<PHINode>(Val)) {
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PHINode *NewPhi = static_cast<PHINode *>(NewInsts[PHI]);
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for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) {
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Value *NewIncoming = PHI->getIncomingValue(I);
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if (NewInsts.find(NewIncoming) != NewInsts.end())
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NewIncoming = NewInsts[NewIncoming];
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NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I));
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}
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}
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}
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// If required, create a inttoptr instruction.
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Value *NewBase = Base;
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setInsertionPoint(Builder, Base, false);
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if (!Base->getType()->isPointerTy())
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NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(),
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Start->getName() + "to.ptr");
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for (Value *Val : Explored) {
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if (Val == Base)
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continue;
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// Depending on the type, for external users we have to emit
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// a GEP or a GEP + ptrtoint.
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if (isa<Instruction>(NewInsts[Val]))
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setInsertionPoint(Builder, NewInsts[Val], false);
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else
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setInsertionPoint(Builder, NewBase, false);
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Value *GEP =
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Builder.CreateInBoundsGEP(Start->getType()->getPointerElementType(),
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NewBase, makeArrayRef(NewInsts[Val]),
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Val->getName() + ".ptr");
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if (!Val->getType()->isPointerTy()) {
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Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(),
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Val->getName() + ".conv");
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GEP = Cast;
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}
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Val->replaceAllUsesWith(GEP);
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}
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return NewInsts[Start];
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}
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/// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express
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/// the input Value as a GEP constant indexed GEP. Returns a pair containing
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/// the GEPs Pointer and Index.
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static std::pair<Value *, Value *>
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getAsConstantIndexedAddress(Value *V, const DataLayout &DL) {
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Type *IndexType =
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IntegerType::get(V->getContext(),
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DL.getPointerTypeSizeInBits(V->getType()));
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Constant *Index = ConstantInt::getNullValue(IndexType);
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while (true) {
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if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
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// We accept only inbouds GEPs here to exclude the possibility of
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// overflow.
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if (!GEP->isInBounds())
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break;
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if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1) {
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V = GEP->getOperand(0);
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Constant *GEPIndex = static_cast<Constant *>(GEP->getOperand(1));
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Index = ConstantExpr::getAdd(
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Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType));
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continue;
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}
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break;
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}
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if (auto *CI = dyn_cast<IntToPtrInst>(V)) {
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if (!CI->isNoopCast(DL))
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break;
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V = CI->getOperand(0);
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continue;
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}
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if (auto *CI = dyn_cast<PtrToIntInst>(V)) {
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if (!CI->isNoopCast(DL))
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break;
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V = CI->getOperand(0);
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continue;
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}
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break;
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}
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return {V, Index};
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}
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// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.
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// We can look through PHIs, GEPs and casts in order to determine a
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// common base between GEPLHS and RHS.
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static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS,
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ICmpInst::Predicate Cond,
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const DataLayout &DL) {
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if (!GEPLHS->hasAllConstantIndices())
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return nullptr;
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Value *PtrBase, *Index;
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std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL);
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// The set of nodes that will take part in this transformation.
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SetVector<Value *> Nodes;
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if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes))
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return nullptr;
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// We know we can re-write this as
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// ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)
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// Since we've only looked through inbouds GEPs we know that we
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// can't have overflow on either side. We can therefore re-write
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// this as:
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// OFFSET1 cmp OFFSET2
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Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes);
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// RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written
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// GEP having PtrBase as the pointer base, and has returned in NewRHS the
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// offset. Since Index is the offset of LHS to the base pointer, we will now
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// compare the offsets instead of comparing the pointers.
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return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS);
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}
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/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
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/// else. At this point we know that the GEP is on the LHS of the comparison.
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Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
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@ -989,9 +674,8 @@ Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
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}
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// Otherwise, the base pointers are different and the indices are
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// different. Try convert this to an indexed compare by looking through
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// PHIs/casts.
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return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
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// different, bail out.
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return nullptr;
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}
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// If one of the GEPs has all zero indices, recurse.
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@ -1043,10 +727,7 @@ Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
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return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
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}
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}
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// Try convert this to an indexed compare by looking through PHIs/casts as a
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// last resort.
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return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
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return nullptr;
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}
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Instruction *InstCombiner::FoldAllocaCmp(ICmpInst &ICI, AllocaInst *Alloca,
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@ -1,100 +0,0 @@
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; RUN: opt -instcombine -S < %s | FileCheck %s
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:64:64-v128:128:128-a0:0:64"
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define i32 *@test1(i32* %A, i32 %Offset) {
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entry:
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%tmp = getelementptr inbounds i32, i32* %A, i32 %Offset
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br label %bb
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bb:
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%RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
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%LHS = getelementptr inbounds i32, i32* %A, i32 100
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%RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
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%cond = icmp ult i32 * %LHS, %RHS
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br i1 %cond, label %bb2, label %bb
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bb2:
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ret i32* %RHS
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; CHECK-LABEL: @test1(
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; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ]
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; CHECK: %[[ADD]] = add i32 %[[INDEX]], 1
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; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100
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; CHECK: br i1 %cond, label %bb2, label %bb
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; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %A, i32 %[[INDEX]]
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; CHECK: ret i32* %[[PTR]]
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}
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define i32 *@test2(i32 %A, i32 %Offset) {
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entry:
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%A.ptr = inttoptr i32 %A to i32*
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%tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset
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br label %bb
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bb:
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%RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
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%LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100
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%RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
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%cmp0 = ptrtoint i32 *%LHS to i32
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%cmp1 = ptrtoint i32 *%RHS to i32
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%cond = icmp ult i32 %cmp0, %cmp1
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br i1 %cond, label %bb2, label %bb
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bb2:
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ret i32* %RHS
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; CHECK-LABEL: @test2(
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; CHECK: %[[TOPTR:[0-9A-Za-z.]+]] = inttoptr i32 %[[ADD:[0-9A-Za-z.]+]] to i32*
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; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ]
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; CHECK: %[[ADD]] = add i32 %[[INDEX]], 1
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; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100
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; CHECK: br i1 %cond, label %bb2, label %bb
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; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %[[TOPTR]], i32 %[[INDEX]]
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; CHECK: ret i32* %[[PTR]]
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}
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; Perform the transformation only if we know that the GEPs used are inbounds.
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define i32 *@test3(i32* %A, i32 %Offset) {
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entry:
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%tmp = getelementptr i32, i32* %A, i32 %Offset
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br label %bb
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bb:
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%RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
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%LHS = getelementptr i32, i32* %A, i32 100
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%RHS.next = getelementptr i32, i32* %RHS, i64 1
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%cond = icmp ult i32 * %LHS, %RHS
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br i1 %cond, label %bb2, label %bb
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bb2:
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ret i32* %RHS
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; CHECK-LABEL: @test3(
|
||||
; CHECK-NOT: %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100
|
||||
}
|
||||
|
||||
; An inttoptr that requires an extension or truncation will be opaque when determining
|
||||
; the base pointer. In this case we can still perform the transformation by considering
|
||||
; A.ptr as being the base pointer.
|
||||
define i32 *@test4(i16 %A, i32 %Offset) {
|
||||
entry:
|
||||
%A.ptr = inttoptr i16 %A to i32*
|
||||
%tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset
|
||||
br label %bb
|
||||
|
||||
bb:
|
||||
%RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ]
|
||||
%LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100
|
||||
%RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1
|
||||
%cmp0 = ptrtoint i32 *%LHS to i32
|
||||
%cmp1 = ptrtoint i32 *%RHS to i32
|
||||
%cond = icmp ult i32 %cmp0, %cmp1
|
||||
br i1 %cond, label %bb2, label %bb
|
||||
|
||||
bb2:
|
||||
ret i32* %RHS
|
||||
|
||||
; CHECK-LABEL: @test4(
|
||||
; CHECK: %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user