From 4bc625cae08a82b8a49f2d044c75a4fcf9788cb7 Mon Sep 17 00:00:00 2001 From: Alina Sbirlea Date: Tue, 30 Jul 2019 20:10:33 +0000 Subject: [PATCH] [MemorySSA] Extend allowed behavior for simplified instructions. Summary: LoopRotate may simplify instructions, leading to the new instructions not having memory accesses created for them. Allow this behavior, by allowing the new access to be null when the template is null, and looking upwards for the proper defined access when dealing with simplified instructions. Reviewers: george.burgess.iv Subscribers: jlebar, Prazek, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D65338 llvm-svn: 367352 --- llvm/include/llvm/Analysis/MemorySSA.h | 3 +- llvm/lib/Analysis/MemorySSA.cpp | 12 ++-- llvm/lib/Analysis/MemorySSAUpdater.cpp | 66 ++++++++++++++-------- .../MemorySSA/loop-rotate-simplified-clone.ll | 29 ++++++++++ 4 files changed, 82 insertions(+), 28 deletions(-) create mode 100644 llvm/test/Analysis/MemorySSA/loop-rotate-simplified-clone.ll diff --git a/llvm/include/llvm/Analysis/MemorySSA.h b/llvm/include/llvm/Analysis/MemorySSA.h index b7730be..282290b 100644 --- a/llvm/include/llvm/Analysis/MemorySSA.h +++ b/llvm/include/llvm/Analysis/MemorySSA.h @@ -830,7 +830,8 @@ protected: void insertIntoListsBefore(MemoryAccess *, const BasicBlock *, AccessList::iterator); MemoryUseOrDef *createDefinedAccess(Instruction *, MemoryAccess *, - const MemoryUseOrDef *Template = nullptr); + const MemoryUseOrDef *Template = nullptr, + bool CreationMustSucceed = true); private: template class ClobberWalkerBase; diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp index 17f5d9b..5df56dd 100644 --- a/llvm/lib/Analysis/MemorySSA.cpp +++ b/llvm/lib/Analysis/MemorySSA.cpp @@ -1687,13 +1687,15 @@ MemoryPhi *MemorySSA::createMemoryPhi(BasicBlock *BB) { MemoryUseOrDef *MemorySSA::createDefinedAccess(Instruction *I, MemoryAccess *Definition, - const MemoryUseOrDef *Template) { + const MemoryUseOrDef *Template, + bool CreationMustSucceed) { assert(!isa(I) && "Cannot create a defined access for a PHI"); MemoryUseOrDef *NewAccess = createNewAccess(I, AA, Template); - assert( - NewAccess != nullptr && - "Tried to create a memory access for a non-memory touching instruction"); - NewAccess->setDefiningAccess(Definition); + if (CreationMustSucceed) + assert(NewAccess != nullptr && "Tried to create a memory access for a " + "non-memory touching instruction"); + if (NewAccess) + NewAccess->setDefiningAccess(Definition); return NewAccess; } diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp index 4c1feee..42bbe74 100644 --- a/llvm/lib/Analysis/MemorySSAUpdater.cpp +++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp @@ -480,29 +480,47 @@ void MemorySSAUpdater::removeDuplicatePhiEdgesBetween(const BasicBlock *From, } } +static MemoryAccess *getNewDefiningAccessForClone(MemoryAccess *MA, + const ValueToValueMapTy &VMap, + PhiToDefMap &MPhiMap, + bool CloneWasSimplified, + MemorySSA *MSSA) { + MemoryAccess *InsnDefining = MA; + if (MemoryDef *DefMUD = dyn_cast(InsnDefining)) { + if (!MSSA->isLiveOnEntryDef(DefMUD)) { + Instruction *DefMUDI = DefMUD->getMemoryInst(); + assert(DefMUDI && "Found MemoryUseOrDef with no Instruction."); + if (Instruction *NewDefMUDI = + cast_or_null(VMap.lookup(DefMUDI))) { + InsnDefining = MSSA->getMemoryAccess(NewDefMUDI); + if (!CloneWasSimplified) + assert(InsnDefining && "Defining instruction cannot be nullptr."); + else if (!InsnDefining || isa(InsnDefining)) { + // The clone was simplified, it's no longer a MemoryDef, look up. + auto DefIt = DefMUD->getDefsIterator(); + // Since simplified clones only occur in single block cloning, a + // previous definition must exist, otherwise NewDefMUDI would not + // have been found in VMap. + assert(DefIt != MSSA->getBlockDefs(DefMUD->getBlock())->begin() && + "Previous def must exist"); + InsnDefining = getNewDefiningAccessForClone( + &*(--DefIt), VMap, MPhiMap, CloneWasSimplified, MSSA); + } + } + } + } else { + MemoryPhi *DefPhi = cast(InsnDefining); + if (MemoryAccess *NewDefPhi = MPhiMap.lookup(DefPhi)) + InsnDefining = NewDefPhi; + } + assert(InsnDefining && "Defining instruction cannot be nullptr."); + return InsnDefining; +} + void MemorySSAUpdater::cloneUsesAndDefs(BasicBlock *BB, BasicBlock *NewBB, const ValueToValueMapTy &VMap, PhiToDefMap &MPhiMap, bool CloneWasSimplified) { - auto GetNewDefiningAccess = [&](MemoryAccess *MA) -> MemoryAccess * { - MemoryAccess *InsnDefining = MA; - if (MemoryUseOrDef *DefMUD = dyn_cast(InsnDefining)) { - if (!MSSA->isLiveOnEntryDef(DefMUD)) { - Instruction *DefMUDI = DefMUD->getMemoryInst(); - assert(DefMUDI && "Found MemoryUseOrDef with no Instruction."); - if (Instruction *NewDefMUDI = - cast_or_null(VMap.lookup(DefMUDI))) - InsnDefining = MSSA->getMemoryAccess(NewDefMUDI); - } - } else { - MemoryPhi *DefPhi = cast(InsnDefining); - if (MemoryAccess *NewDefPhi = MPhiMap.lookup(DefPhi)) - InsnDefining = NewDefPhi; - } - assert(InsnDefining && "Defining instruction cannot be nullptr."); - return InsnDefining; - }; - const MemorySSA::AccessList *Acc = MSSA->getBlockAccesses(BB); if (!Acc) return; @@ -519,9 +537,13 @@ void MemorySSAUpdater::cloneUsesAndDefs(BasicBlock *BB, BasicBlock *NewBB, if (Instruction *NewInsn = dyn_cast_or_null(VMap.lookup(Insn))) { MemoryAccess *NewUseOrDef = MSSA->createDefinedAccess( - NewInsn, GetNewDefiningAccess(MUD->getDefiningAccess()), - CloneWasSimplified ? nullptr : MUD); - MSSA->insertIntoListsForBlock(NewUseOrDef, NewBB, MemorySSA::End); + NewInsn, + getNewDefiningAccessForClone(MUD->getDefiningAccess(), VMap, + MPhiMap, CloneWasSimplified, MSSA), + /*Template=*/CloneWasSimplified ? nullptr : MUD, + /*CreationMustSucceed=*/CloneWasSimplified ? false : true); + if (NewUseOrDef) + MSSA->insertIntoListsForBlock(NewUseOrDef, NewBB, MemorySSA::End); } } } diff --git a/llvm/test/Analysis/MemorySSA/loop-rotate-simplified-clone.ll b/llvm/test/Analysis/MemorySSA/loop-rotate-simplified-clone.ll new file mode 100644 index 0000000..3d0efc6 --- /dev/null +++ b/llvm/test/Analysis/MemorySSA/loop-rotate-simplified-clone.ll @@ -0,0 +1,29 @@ +; RUN: opt -verify-memoryssa -enable-mssa-loop-dependency -loop-rotate %s -S | FileCheck %s +; REQUIRES: asserts + +; CHECK-LABEL: @test() +define dso_local void @test() { +entry: + br label %preheader + +preheader: + br label %l39 + +l39: + %v40 = phi float (float)* [ @foo, %preheader ], [ %v43, %crit_edge ] + %v41 = call float %v40(float undef) + %v42 = load i32, i32* undef, align 8 + br i1 undef, label %crit_edge, label %loopexit + +crit_edge: + %v43 = load float (float)*, float (float)** undef, align 8 + br label %l39 + +loopexit: + unreachable +} + +; Function Attrs: readnone +declare dso_local float @foo(float) #0 align 32 + +attributes #0 = { readnone } -- 2.7.4