Index: lib/Analysis/ScalarEvolutionExpander.cpp =================================================================== --- lib/Analysis/ScalarEvolutionExpander.cpp +++ lib/Analysis/ScalarEvolutionExpander.cpp @@ -1703,9 +1703,28 @@ if (!V) V = visit(S); - else if (VO.second) - V = Builder.CreateSub(V, VO.second); - + else if (VO.second) { + if (PointerType *Vty = dyn_cast(V->getType())) { + Type *Ety = Vty->getPointerElementType(); + int64_t Offset = VO.second->getSExtValue(); + int64_t ESize = SE.getTypeSizeInBits(Ety); + if ((Offset * 8) % ESize == 0) { + ConstantInt *Idx = + ConstantInt::getSigned(VO.second->getType(), -(Offset * 8) / ESize); + V = Builder.CreateGEP(Ety, V, Idx, "scevgep"); + } else { + ConstantInt *Idx = + ConstantInt::getSigned(VO.second->getType(), -Offset); + unsigned AS = Vty->getAddressSpace(); + V = Builder.CreateBitCast(V, Type::getInt8PtrTy(SE.getContext(), AS)); + V = Builder.CreateGEP(Type::getInt8Ty(SE.getContext()), V, Idx, + "uglygep"); + V = Builder.CreateBitCast(V, Vty); + } + } else { + V = Builder.CreateSub(V, VO.second); + } + } // Remember the expanded value for this SCEV at this location. // // This is independent of PostIncLoops. The mapped value simply materializes Index: test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll =================================================================== --- test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll +++ test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll @@ -0,0 +1,36 @@ +; PR30213. Check scev expand will generate correct code if the value +; in ValueOffsetPair is of pointer type. +; RUN: opt < %s -loop-reduce -S | FileCheck %s + +; CHECK: %ptr4.ptr1 = select i1 %cmp.i, i8* %ptr4, i8* %ptr1 +; CHECK-NEXT: %scevgep = getelementptr i8, i8* %ptr4.ptr1, i32 1 +; CHECK-NEXT: br label %while.cond.i + +target datalayout = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128" +target triple = "i386-apple-macosx10.12.0" + +; Function Attrs: nounwind optsize ssp +define void @Foo() { +entry: + switch i2 undef, label %sw.epilog102 [ + i2 -2, label %sw.bb28 + ] + +sw.bb28: ; preds = %entry + %0 = load i8*, i8** undef, align 2 + %ptr1 = getelementptr inbounds i8, i8* undef, i32 -1 + %ptr4 = getelementptr inbounds i8, i8* %0, i32 -1 + %cmp.i = icmp ult i8* undef, %0 + %ptr4.ptr1 = select i1 %cmp.i, i8* %ptr4, i8* %ptr1 + br label %while.cond.i + +while.cond.i: ; preds = %while.cond.i, %sw.bb28 + %currPtr.1.i = phi i8* [ %incdec.ptr.i, %while.cond.i ], [ %ptr4.ptr1, %sw.bb28 ] + %incdec.ptr.i = getelementptr inbounds i8, i8* %currPtr.1.i, i32 1 + %1 = load i8, i8* %incdec.ptr.i, align 1 + br label %while.cond.i + +sw.epilog102: ; preds = %entry + unreachable +} +