[llvm] r251451 - [AliasSetTracker] Use mod/ref information for UnknownInstr

Wed Oct 28 15:03:14 PDT 2015

----- Original Message -----
> From: "Juergen Ributzka" <juergen at apple.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: llvm-commits at lists.llvm.org
> Sent: Wednesday, October 28, 2015 4:56:59 PM
> Subject: Re: [llvm] r251451 - [AliasSetTracker] Use mod/ref information for UnknownInstr
> 
> Hi Hal,
> 
> 
> looks like this change broke the stage2 compiler:
> http://lab.llvm.org:8080/green/job/clang-stage2-configure-Rlto/6989/
> 
> 
> Could you please revert the patch?
> 

Yep. Will do.

 -Hal

> 
> Thanks
> 
> 
> Cheers,
> Juergen
> 
> 
> On Oct 27, 2015, at 1:37 PM, Hal Finkel via llvm-commits <
> llvm-commits at lists.llvm.org > wrote:
> 
> 
> Author: hfinkel
> Date: Tue Oct 27 15:37:04 2015
> New Revision: 251451
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=251451&view=rev
> Log:
> [AliasSetTracker] Use mod/ref information for UnknownInstr
> 
> AliasSetTracker does not need to convert the access mode to
> ModRefAccess if the
> new visited UnknownInst has only 'REF' modrefinfo to existing
> pointers in the
> sets.
> 
> Patch by Andrew Zhogin!
> 
> Added:
> llvm/trunk/test/Transforms/LICM/licm_call_referenced_ptr.ll
> Modified:
> llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
> llvm/trunk/lib/Analysis/AliasSetTracker.cpp
> 
> Modified: llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/AliasSetTracker.h?rev=251451&r1=251450&r2=251451&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Analysis/AliasSetTracker.h (original)
> +++ llvm/trunk/include/llvm/Analysis/AliasSetTracker.h Tue Oct 27
> 15:37:04 2015
> @@ -124,12 +124,7 @@ class AliasSet : public ilist_node<Alias
> /// memory (and not any particular access), whether it modifies or
> references
> /// the memory, or whether it does both. The lattice goes from
> "NoAccess" to
> /// either RefAccess or ModAccess, then to ModRefAccess as necessary.
> - enum AccessLattice {
> - NoAccess = 0,
> - RefAccess = 1,
> - ModAccess = 2,
> - ModRefAccess = RefAccess | ModAccess
> - };
> + typedef ModRefInfo AccessLattice;
> unsigned Access : 2;
> 
> /// The kind of alias relationship between pointers of the set.
> @@ -160,8 +155,8 @@ class AliasSet : public ilist_node<Alias
> 
> public:
> /// Accessors...
> - bool isRef() const { return Access & RefAccess; }
> - bool isMod() const { return Access & ModAccess; }
> + bool isRef() const { return Access & MRI_Ref; }
> + bool isMod() const { return Access & MRI_Mod; }
> bool isMustAlias() const { return Alias == SetMustAlias; }
> bool isMayAlias() const { return Alias == SetMayAlias; }
> 
> @@ -226,7 +221,7 @@ private:
> friend struct ilist_sentinel_traits<AliasSet>;
> AliasSet()
> : PtrList(nullptr), PtrListEnd(&PtrList), Forward(nullptr),
> RefCount(0),
> - Access(NoAccess), Alias(SetMustAlias), Volatile(false) {
> + Access(MRI_NoModRef), Alias(SetMustAlias), Volatile(false) {
> }
> 
> AliasSet(const AliasSet &AS) = delete;
> @@ -254,9 +249,9 @@ private:
> void removeFromTracker(AliasSetTracker &AST);
> 
> void addPointer(AliasSetTracker &AST, PointerRec &Entry, uint64_t
> Size,
> - const AAMDNodes &AAInfo,
> + const AAMDNodes &AAInfo, ModRefInfo MR,
> bool KnownMustAlias = false);
> - void addUnknownInst(Instruction *I, AliasAnalysis &AA);
> + void addUnknownInst(Instruction *I, AliasAnalysis &AA, ModRefInfo
> MR);
> void removeUnknownInst(AliasSetTracker &AST, Instruction *I) {
> bool WasEmpty = UnknownInsts.empty();
> for (size_t i = 0, e = UnknownInsts.size(); i != e; ++i)
> @@ -273,10 +268,18 @@ private:
> public:
> /// aliasesPointer - Return true if the specified pointer "may" (or
> must)
> /// alias one of the members in the set.
> - ///
> + /// MRcommon - if Ptr is aliased by existing UnknownInsts,
> + /// then not-null MRcommon will be set to the worst ModRefInfo met
> + ///
> bool aliasesPointer(const Value *Ptr, uint64_t Size, const AAMDNodes
> &AAInfo,
> - AliasAnalysis &AA) const;
> - bool aliasesUnknownInst(const Instruction *Inst, AliasAnalysis &AA)
> const;
> + AliasAnalysis &AA, ModRefInfo* MRcommon = nullptr) const;
> + /// aliasesUnknownInst - Return true if the specified UnknownInst
> + /// has not-null ModRefInfo (not MRI_NoModRef) with some
> + /// pointer or UnknownInst already existing in AliasSet
> + /// MRcommon - not-null MRcommon will be set to the worst
> ModRefInfo met
> + ///
> + bool aliasesUnknownInst(const Instruction *Inst, AliasAnalysis &AA,
> + ModRefInfo* MRcommon = nullptr) const;
> };
> 
> inline raw_ostream& operator<<(raw_ostream &OS, const AliasSet &AS) {
> @@ -434,9 +437,11 @@ private:
> return AS;
> }
> AliasSet *findAliasSetForPointer(const Value *Ptr, uint64_t Size,
> - const AAMDNodes &AAInfo);
> + const AAMDNodes &AAInfo,
> + ModRefInfo* MRcommonPtr = nullptr);
> 
> - AliasSet *findAliasSetForUnknownInst(Instruction *Inst);
> + AliasSet *findAliasSetForUnknownInst(Instruction *Inst,
> + ModRefInfo* MRcommonPtr = nullptr);
> };
> 
> inline raw_ostream& operator<<(raw_ostream &OS, const AliasSetTracker
> &AST) {
> 
> Modified: llvm/trunk/lib/Analysis/AliasSetTracker.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasSetTracker.cpp?rev=251451&r1=251450&r2=251451&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/AliasSetTracker.cpp (original)
> +++ llvm/trunk/lib/Analysis/AliasSetTracker.cpp Tue Oct 27 15:37:04
> 2015
> @@ -95,7 +95,7 @@ void AliasSet::removeFromTracker(AliasSe
> 
> void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
> uint64_t Size, const AAMDNodes &AAInfo,
> - bool KnownMustAlias) {
> + ModRefInfo MR, bool KnownMustAlias) {
> assert(!Entry.hasAliasSet() && "Entry already in set!");
> 
> // Check to see if we have to downgrade to _may_ alias.
> @@ -112,6 +112,9 @@ void AliasSet::addPointer(AliasSetTracke
> assert(Result != NoAlias && "Cannot be part of must set!");
> }
> 
> + // upgrading access if existing UnknownInst has ModRef with new
> pointer
> + Access |= MR;
> +
> Entry.setAliasSet(this);
> Entry.updateSizeAndAAInfo(Size, AAInfo);
> 
> @@ -123,20 +126,34 @@ void AliasSet::addPointer(AliasSetTracke
> addRef(); // Entry points to alias set.
> }
> 
> -void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
> +void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA,
> + ModRefInfo MR) {
> if (UnknownInsts.empty())
> addRef();
> UnknownInsts.emplace_back(I);
> 
> if (!I->mayWriteToMemory()) {
> Alias = SetMayAlias;
> - Access |= RefAccess;
> + Access |= MRI_Ref;
> return;
> }
> 
> - // FIXME: This should use mod/ref information to make this not suck
> so bad
> Alias = SetMayAlias;
> - Access = ModRefAccess;
> + Access |= MR;
> +}
> +
> +namespace {
> + /// returns true if there is no request of worst ModRefInfo
> + /// (MRcommonPtr is null)
> + /// or when achieved maximum ModRefInfo (MRI_ModRef).
> + bool processMR(ModRefInfo MR, ModRefInfo* MRcommonPtr, ModRefInfo&
> MRcommon) {
> + MRcommon = ModRefInfo(MRcommon | MR);
> + return !MRcommonPtr || (MRcommon == MRI_ModRef);
> + }
> + bool fillExitMR(ModRefInfo* MRcommonPtr, ModRefInfo& MRcommon) {
> + if (MRcommonPtr) *MRcommonPtr = MRcommon;
> + return MRcommon != MRI_NoModRef;
> + }
> }
> 
> /// aliasesPointer - Return true if the specified pointer "may" (or
> must)
> @@ -144,7 +161,8 @@ void AliasSet::addUnknownInst(Instructio
> ///
> bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
> const AAMDNodes &AAInfo,
> - AliasAnalysis &AA) const {
> + AliasAnalysis &AA,
> + ModRefInfo* MRcommonPtr) const {
> if (Alias == SetMustAlias) {
> assert(UnknownInsts.empty() && "Illegal must alias set!");
> 
> @@ -164,35 +182,44 @@ bool AliasSet::aliasesPointer(const Valu
> MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
> return true;
> 
> + // to gather worst ModRefInfo
> + ModRefInfo MRcommon = MRI_NoModRef;
> +
> // Check the unknown instructions...
> if (!UnknownInsts.empty()) {
> for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
> - if (AA.getModRefInfo(UnknownInsts[i],
> - MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
> - return true;
> + if (processMR(AA.getModRefInfo(UnknownInsts[i],
> + MemoryLocation(Ptr, Size, AAInfo)), MRcommonPtr, MRcommon))
> + return fillExitMR(MRcommonPtr, MRcommon);
> }
> 
> - return false;
> + return fillExitMR(MRcommonPtr, MRcommon);
> }
> 
> bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
> - AliasAnalysis &AA) const {
> + AliasAnalysis &AA,
> + ModRefInfo* MRcommonPtr) const {
> if (!Inst->mayReadOrWriteMemory())
> return false;
> 
> + // to gather worst ModRefInfo
> + ModRefInfo MRcommon = MRI_NoModRef;
> +
> for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
> ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
> - if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
> - AA.getModRefInfo(C2, C1) != MRI_NoModRef)
> - return true;
> + if (!C1 || !C2 ||
> + processMR(AA.getModRefInfo(C1, C2), MRcommonPtr, MRcommon) ||
> + processMR(AA.getModRefInfo(C2, C1), MRcommonPtr, MRcommon))
> + return fillExitMR(MRcommonPtr, MRcommon);
> }
> 
> - for (iterator I = begin(), E = end(); I != E; ++I)
> - if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(),
> I.getSize(),
> - I.getAAInfo())) != MRI_NoModRef)
> - return true;
> -
> - return false;
> + for (iterator I = begin(), E = end(); I != E; ++I) {
> + ModRefInfo MR = AA.getModRefInfo(
> + Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo()));
> + if (processMR(MR, MRcommonPtr, MRcommon))
> + return fillExitMR(MRcommonPtr, MRcommon);
> + }
> + return fillExitMR(MRcommonPtr, MRcommon);
> }
> 
> void AliasSetTracker::clear() {
> @@ -214,11 +241,15 @@ void AliasSetTracker::clear() {
> ///
> AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
> uint64_t Size,
> - const AAMDNodes &AAInfo) {
> + const AAMDNodes &AAInfo,
> + ModRefInfo* MRcommonPtr) {
> AliasSet *FoundSet = nullptr;
> for (iterator I = begin(), E = end(); I != E;) {
> iterator Cur = I++;
> - if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA))
> continue;
> + ModRefInfo MR = MRI_NoModRef;
> + if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA,
> &MR))
> + continue;
> + *MRcommonPtr = ModRefInfo(*MRcommonPtr | MR);
> 
> if (!FoundSet) { // If this is the first alias set ptr can go into.
> FoundSet = &*Cur; // Remember it.
> @@ -248,12 +279,15 @@ bool AliasSetTracker::containsUnknown(co
> return false;
> }
> 
> -AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction
> *Inst) {
> +AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction
> *Inst,
> + ModRefInfo* MRcommonPtr) {
> AliasSet *FoundSet = nullptr;
> for (iterator I = begin(), E = end(); I != E;) {
> iterator Cur = I++;
> - if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
> + ModRefInfo MR = MRI_NoModRef;
> + if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA, &MR))
> continue;
> + *MRcommonPtr = ModRefInfo(*MRcommonPtr | MR);
> if (!FoundSet) // If this is the first alias set ptr can go into.
> FoundSet = &*Cur; // Remember it.
> else if (!Cur->Forward) // Otherwise, we must merge the sets.
> @@ -279,22 +313,23 @@ AliasSet &AliasSetTracker::getAliasSetFo
> return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
> }
> 
> - if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo)) {
> + ModRefInfo MR = MRI_NoModRef;
> + if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, AAInfo,
> &MR)) {
> // Add it to the alias set it aliases.
> - AS->addPointer(*this, Entry, Size, AAInfo);
> + AS->addPointer(*this, Entry, Size, AAInfo, MR);
> return *AS;
> }
> 
> if (New) *New = true;
> // Otherwise create a new alias set to hold the loaded pointer.
> AliasSets.push_back(new AliasSet());
> - AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
> + AliasSets.back().addPointer(*this, Entry, Size, AAInfo,
> MRI_NoModRef);
> return AliasSets.back();
> }
> 
> bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes
> &AAInfo) {
> bool NewPtr;
> - addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
> + addPointer(Ptr, Size, AAInfo, MRI_NoModRef, NewPtr);
> return NewPtr;
> }
> 
> @@ -305,7 +340,7 @@ bool AliasSetTracker::add(LoadInst *LI)
> AAMDNodes AAInfo;
> LI->getAAMetadata(AAInfo);
> 
> - AliasSet::AccessLattice Access = AliasSet::RefAccess;
> + AliasSet::AccessLattice Access = MRI_Ref;
> bool NewPtr;
> const DataLayout &DL = LI->getModule()->getDataLayout();
> AliasSet &AS = addPointer(LI->getOperand(0),
> @@ -321,7 +356,7 @@ bool AliasSetTracker::add(StoreInst *SI)
> AAMDNodes AAInfo;
> SI->getAAMetadata(AAInfo);
> 
> - AliasSet::AccessLattice Access = AliasSet::ModAccess;
> + AliasSet::AccessLattice Access = MRI_Mod;
> bool NewPtr;
> const DataLayout &DL = SI->getModule()->getDataLayout();
> Value *Val = SI->getOperand(0);
> @@ -338,7 +373,7 @@ bool AliasSetTracker::add(VAArgInst *VAA
> 
> bool NewPtr;
> addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
> - AliasSet::ModRefAccess, NewPtr);
> + MRI_ModRef, NewPtr);
> return NewPtr;
> }
> 
> @@ -349,14 +384,15 @@ bool AliasSetTracker::addUnknown(Instruc
> if (!Inst->mayReadOrWriteMemory())
> return true; // doesn't alias anything
> 
> - AliasSet *AS = findAliasSetForUnknownInst(Inst);
> + ModRefInfo MR = MRI_NoModRef;
> + AliasSet *AS = findAliasSetForUnknownInst(Inst, &MR);
> if (AS) {
> - AS->addUnknownInst(Inst, AA);
> + AS->addUnknownInst(Inst, AA, MR);
> return false;
> }
> AliasSets.push_back(new AliasSet());
> AS = &AliasSets.back();
> - AS->addUnknownInst(Inst, AA);
> + AS->addUnknownInst(Inst, AA, MR);
> return true;
> }
> 
> @@ -556,7 +592,7 @@ void AliasSetTracker::copyValue(Value *F
> I = PointerMap.find_as(From);
> AliasSet *AS = I->second->getAliasSet(*this);
> AS->addPointer(*this, Entry, I->second->getSize(),
> - I->second->getAAInfo(),
> + I->second->getAAInfo(), MRI_NoModRef,
> true);
> }
> 
> @@ -570,10 +606,10 @@ void AliasSet::print(raw_ostream &OS) co
> OS << " AliasSet[" << (const void*)this << ", " << RefCount << "] ";
> OS << (Alias == SetMustAlias ? "must" : "may") << " alias, ";
> switch (Access) {
> - case NoAccess: OS << "No access "; break;
> - case RefAccess: OS << "Ref "; break;
> - case ModAccess: OS << "Mod "; break;
> - case ModRefAccess: OS << "Mod/Ref "; break;
> + case MRI_NoModRef: OS << "No access "; break;
> + case MRI_Ref: OS << "Ref "; break;
> + case MRI_Mod: OS << "Mod "; break;
> + case MRI_ModRef: OS << "Mod/Ref "; break;
> default: llvm_unreachable("Bad value for Access!");
> }
> if (isVolatile()) OS << "[volatile] ";
> 
> Added: llvm/trunk/test/Transforms/LICM/licm_call_referenced_ptr.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/licm_call_referenced_ptr.ll?rev=251451&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/LICM/licm_call_referenced_ptr.ll
> (added)
> +++ llvm/trunk/test/Transforms/LICM/licm_call_referenced_ptr.ll Tue
> Oct 27 15:37:04 2015
> @@ -0,0 +1,40 @@
> +; RUN: opt < %s -basicaa -licm -S | FileCheck %s
> +
> +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8*
> nocapture, i64, i32, i1) nounwind
> +
> +define i8 @"main"() {
> +entry:
> + %A = alloca [64 x i8]
> + %B = alloca [4 x i8]
> + %A0 = getelementptr [64 x i8], [64 x i8]* %A, i32 0, i32 0
> + %B0 = getelementptr [4 x i8], [4 x i8]* %B, i32 0, i32 0
> + %B1 = getelementptr [4 x i8], [4 x i8]* %B, i32 0, i32 1
> + %B2 = getelementptr [4 x i8], [4 x i8]* %B, i32 0, i32 2
> + %B3 = getelementptr [4 x i8], [4 x i8]* %B, i32 0, i32 3
> + store i8 0, i8* %A0
> + store i8 32, i8* %B0
> + store i8 73, i8* %B1
> + store i8 74, i8* %B2
> + store i8 75, i8* %B3
> + br label %loop_begin
> +
> +loop_begin:
> +; CHECK: loop_begin:
> +; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A0, i8* %B0,
> i64 4, i32 4, i1 false)
> +
> + %b_val = load i8, i8* %B0
> +
> + ; *B is invariant in loop and limit_val must be hoisted
> + %limit_val_1 = mul i8 %b_val, 3
> + %limit_val = add i8 %limit_val_1, 67
> +
> + call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A0, i8* %B0, i64 4, i32
> 4, i1 false)
> +
> + %exitcond = icmp ugt i8 164, %limit_val
> + br i1 %exitcond, label %after_loop, label %loop_begin
> +
> +after_loop:
> + %b_val_result = load i8, i8* %B0
> + ret i8 %b_val_result
> +}
> +
> 
> 
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> 
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory