+void SeparateConstOffsetFromGEP::lowerToSingleIndexGEPs(
+ GetElementPtrInst *Variadic, int64_t AccumulativeByteOffset) {
+ IRBuilder<> Builder(Variadic);
+ Type *IntPtrTy = DL->getIntPtrType(Variadic->getType());
+
+ Type *I8PtrTy =
+ Builder.getInt8PtrTy(Variadic->getType()->getPointerAddressSpace());
+ Value *ResultPtr = Variadic->getOperand(0);
+ Loop *L = LI->getLoopFor(Variadic->getParent());
+ // Check if the base is not loop invariant or used more than once.
+ bool isSwapCandidate =
+ L && L->isLoopInvariant(ResultPtr) &&
+ !hasMoreThanOneUseInLoop(ResultPtr, L);
+ Value *FirstResult = nullptr;
+
+ if (ResultPtr->getType() != I8PtrTy)
+ ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy);
+
+ gep_type_iterator GTI = gep_type_begin(*Variadic);
+ // Create an ugly GEP for each sequential index. We don't create GEPs for
+ // structure indices, as they are accumulated in the constant offset index.
+ for (unsigned I = 1, E = Variadic->getNumOperands(); I != E; ++I, ++GTI) {
+ if (isa<SequentialType>(*GTI)) {
+ Value *Idx = Variadic->getOperand(I);
+ // Skip zero indices.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx))
+ if (CI->isZero())
+ continue;
+
+ APInt ElementSize = APInt(IntPtrTy->getIntegerBitWidth(),
+ DL->getTypeAllocSize(GTI.getIndexedType()));
+ // Scale the index by element size.
+ if (ElementSize != 1) {
+ if (ElementSize.isPowerOf2()) {
+ Idx = Builder.CreateShl(
+ Idx, ConstantInt::get(IntPtrTy, ElementSize.logBase2()));
+ } else {
+ Idx = Builder.CreateMul(Idx, ConstantInt::get(IntPtrTy, ElementSize));
+ }
+ }
+ // Create an ugly GEP with a single index for each index.
+ ResultPtr =
+ Builder.CreateGEP(Builder.getInt8Ty(), ResultPtr, Idx, "uglygep");
+ if (FirstResult == nullptr)
+ FirstResult = ResultPtr;
+ }
+ }
+
+ // Create a GEP with the constant offset index.
+ if (AccumulativeByteOffset != 0) {
+ Value *Offset = ConstantInt::get(IntPtrTy, AccumulativeByteOffset);
+ ResultPtr =
+ Builder.CreateGEP(Builder.getInt8Ty(), ResultPtr, Offset, "uglygep");
+ } else
+ isSwapCandidate = false;
+
+ // If we created a GEP with constant index, and the base is loop invariant,
+ // then we swap the first one with it, so LICM can move constant GEP out
+ // later.
+ GetElementPtrInst *FirstGEP = dyn_cast<GetElementPtrInst>(FirstResult);
+ GetElementPtrInst *SecondGEP = dyn_cast<GetElementPtrInst>(ResultPtr);
+ if (isSwapCandidate && isLegalToSwapOperand(FirstGEP, SecondGEP, L))
+ swapGEPOperand(FirstGEP, SecondGEP);
+
+ if (ResultPtr->getType() != Variadic->getType())
+ ResultPtr = Builder.CreateBitCast(ResultPtr, Variadic->getType());
+
+ Variadic->replaceAllUsesWith(ResultPtr);
+ Variadic->eraseFromParent();
+}
+
+void
+SeparateConstOffsetFromGEP::lowerToArithmetics(GetElementPtrInst *Variadic,
+ int64_t AccumulativeByteOffset) {
+ IRBuilder<> Builder(Variadic);
+ Type *IntPtrTy = DL->getIntPtrType(Variadic->getType());
+
+ Value *ResultPtr = Builder.CreatePtrToInt(Variadic->getOperand(0), IntPtrTy);
+ gep_type_iterator GTI = gep_type_begin(*Variadic);
+ // Create ADD/SHL/MUL arithmetic operations for each sequential indices. We
+ // don't create arithmetics for structure indices, as they are accumulated
+ // in the constant offset index.
+ for (unsigned I = 1, E = Variadic->getNumOperands(); I != E; ++I, ++GTI) {
+ if (isa<SequentialType>(*GTI)) {
+ Value *Idx = Variadic->getOperand(I);
+ // Skip zero indices.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx))
+ if (CI->isZero())
+ continue;
+
+ APInt ElementSize = APInt(IntPtrTy->getIntegerBitWidth(),
+ DL->getTypeAllocSize(GTI.getIndexedType()));
+ // Scale the index by element size.
+ if (ElementSize != 1) {
+ if (ElementSize.isPowerOf2()) {
+ Idx = Builder.CreateShl(
+ Idx, ConstantInt::get(IntPtrTy, ElementSize.logBase2()));
+ } else {
+ Idx = Builder.CreateMul(Idx, ConstantInt::get(IntPtrTy, ElementSize));
+ }
+ }
+ // Create an ADD for each index.
+ ResultPtr = Builder.CreateAdd(ResultPtr, Idx);
+ }
+ }
+
+ // Create an ADD for the constant offset index.
+ if (AccumulativeByteOffset != 0) {
+ ResultPtr = Builder.CreateAdd(
+ ResultPtr, ConstantInt::get(IntPtrTy, AccumulativeByteOffset));
+ }
+
+ ResultPtr = Builder.CreateIntToPtr(ResultPtr, Variadic->getType());
+ Variadic->replaceAllUsesWith(ResultPtr);
+ Variadic->eraseFromParent();
+}
+