AA metadata refactoring (introduce AAMDNodes)

In order to enable the preservation of noalias function parameter information
after inlining, and the representation of block-level __restrict__ pointer
information (etc.), additional kinds of aliasing metadata will be introduced.
This metadata needs to be carried around in AliasAnalysis::Location objects
(and MMOs at the SDAG level), and so we need to generalize the current scheme
(which is hard-coded to just one TBAA MDNode*).

This commit introduces only the necessary refactoring to allow for the
introduction of other aliasing metadata types, but does not actually introduce
any (that will come in a follow-up commit). What it does introduce is a new
AAMDNodes structure to hold all of the aliasing metadata nodes associated with
a particular memory-accessing instruction, and uses that structure instead of
the raw MDNode* in AliasAnalysis::Location, etc.

No functionality change intended.

llvm-svn: 213859

5 files changed, 61 insertions, 45 deletions

diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 106eba099ca..43ccb995958 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1669,9 +1669,11 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
                                         LI->getAlignment(),
                                         UnavailablePred->getTerminator());
 
-    // Transfer the old load's TBAA tag to the new load.
-    if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa))
-      NewLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+    // Transfer the old load's AA tags to the new load.
+    AAMDNodes Tags;
+    LI->getAAMetadata(Tags);
+    if (Tags)
+      NewLoad->setAAMetadata(Tags);
 
     // Transfer DebugLoc.
     NewLoad->setDebugLoc(LI->getDebugLoc());
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 21f80385cf4..2b4e3ff00dd 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -26,6 +26,7 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
@@ -888,9 +889,10 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
   if (BBIt != LoadBB->begin())
     return false;
 
-  // If all of the loads and stores that feed the value have the same TBAA tag,
-  // then we can propagate it onto any newly inserted loads.
-  MDNode *TBAATag = LI->getMetadata(LLVMContext::MD_tbaa);
+  // If all of the loads and stores that feed the value have the same AA tags,
+  // then we can propagate them onto any newly inserted loads.
+  AAMDNodes AATags;
+  LI->getAAMetadata(AATags);
 
   SmallPtrSet<BasicBlock*, 8> PredsScanned;
   typedef SmallVector<std::pair<BasicBlock*, Value*>, 8> AvailablePredsTy;
@@ -909,16 +911,16 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
 
     // Scan the predecessor to see if the value is available in the pred.
     BBIt = PredBB->end();
-    MDNode *ThisTBAATag = nullptr;
+    AAMDNodes ThisAATags;
     Value *PredAvailable = FindAvailableLoadedValue(LoadedPtr, PredBB, BBIt, 6,
-                                                    nullptr, &ThisTBAATag);
+                                                    nullptr, &ThisAATags);
     if (!PredAvailable) {
       OneUnavailablePred = PredBB;
       continue;
     }
 
-    // If tbaa tags disagree or are not present, forget about them.
-    if (TBAATag != ThisTBAATag) TBAATag = nullptr;
+    // If AA tags disagree or are not present, forget about them.
+    if (AATags != ThisAATags) AATags = AAMDNodes();
 
     // If so, this load is partially redundant.  Remember this info so that we
     // can create a PHI node.
@@ -978,8 +980,8 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) {
                                  LI->getAlignment(),
                                  UnavailablePred->getTerminator());
     NewVal->setDebugLoc(LI->getDebugLoc());
-    if (TBAATag)
-      NewVal->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+    if (AATags)
+      NewVal->setAAMetadata(AATags);
 
     AvailablePreds.push_back(std::make_pair(UnavailablePred, NewVal));
   }
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index abcceb20050..1673c0f40ff 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -180,9 +180,9 @@ namespace {
     /// store into the memory location pointed to by V.
     ///
     bool pointerInvalidatedByLoop(Value *V, uint64_t Size,
-                                  const MDNode *TBAAInfo) {
+                                  const AAMDNodes &AAInfo) {
       // Check to see if any of the basic blocks in CurLoop invalidate *V.
-      return CurAST->getAliasSetForPointer(V, Size, TBAAInfo).isMod();
+      return CurAST->getAliasSetForPointer(V, Size, AAInfo).isMod();
     }
 
     bool canSinkOrHoistInst(Instruction &I);
@@ -448,8 +448,11 @@ bool LICM::canSinkOrHoistInst(Instruction &I) {
     uint64_t Size = 0;
     if (LI->getType()->isSized())
       Size = AA->getTypeStoreSize(LI->getType());
-    return !pointerInvalidatedByLoop(LI->getOperand(0), Size,
-                                     LI->getMetadata(LLVMContext::MD_tbaa));
+
+    AAMDNodes AAInfo;
+    LI->getAAMetadata(AAInfo);
+
+    return !pointerInvalidatedByLoop(LI->getOperand(0), Size, AAInfo);
   } else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
     // Don't sink or hoist dbg info; it's legal, but not useful.
     if (isa<DbgInfoIntrinsic>(I))
@@ -690,7 +693,7 @@ namespace {
     LoopInfo &LI;
     DebugLoc DL;
     int Alignment;
-    MDNode *TBAATag;
+    AAMDNodes AATags;
 
     Value *maybeInsertLCSSAPHI(Value *V, BasicBlock *BB) const {
       if (Instruction *I = dyn_cast<Instruction>(V))
@@ -714,10 +717,10 @@ namespace {
                  SmallVectorImpl<BasicBlock *> &LEB,
                  SmallVectorImpl<Instruction *> &LIP, PredIteratorCache &PIC,
                  AliasSetTracker &ast, LoopInfo &li, DebugLoc dl, int alignment,
-                 MDNode *TBAATag)
+                 const AAMDNodes &AATags)
         : LoadAndStorePromoter(Insts, S), SomePtr(SP), PointerMustAliases(PMA),
           LoopExitBlocks(LEB), LoopInsertPts(LIP), PredCache(PIC), AST(ast),
-          LI(li), DL(dl), Alignment(alignment), TBAATag(TBAATag) {}
+          LI(li), DL(dl), Alignment(alignment), AATags(AATags) {}
 
     bool isInstInList(Instruction *I,
                       const SmallVectorImpl<Instruction*> &) const override {
@@ -743,7 +746,7 @@ namespace {
         StoreInst *NewSI = new StoreInst(LiveInValue, Ptr, InsertPos);
         NewSI->setAlignment(Alignment);
         NewSI->setDebugLoc(DL);
-        if (TBAATag) NewSI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+        if (AATags) NewSI->setAAMetadata(AATags);
       }
     }
 
@@ -798,11 +801,11 @@ void LICM::PromoteAliasSet(AliasSet &AS,
   // We start with an alignment of one and try to find instructions that allow
   // us to prove better alignment.
   unsigned Alignment = 1;
-  MDNode *TBAATag = nullptr;
+  AAMDNodes AATags;
 
   // Check that all of the pointers in the alias set have the same type.  We
   // cannot (yet) promote a memory location that is loaded and stored in
-  // different sizes.  While we are at it, collect alignment and TBAA info.
+  // different sizes.  While we are at it, collect alignment and AA info.
   for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
     Value *ASIV = ASI->getValue();
     PointerMustAliases.insert(ASIV);
@@ -855,13 +858,12 @@ void LICM::PromoteAliasSet(AliasSet &AS,
       } else
         return; // Not a load or store.
 
-      // Merge the TBAA tags.
+      // Merge the AA tags.
       if (LoopUses.empty()) {
-        // On the first load/store, just take its TBAA tag.
-        TBAATag = UI->getMetadata(LLVMContext::MD_tbaa);
-      } else if (TBAATag) {
-        TBAATag = MDNode::getMostGenericTBAA(TBAATag,
-                                       UI->getMetadata(LLVMContext::MD_tbaa));
+        // On the first load/store, just take its AA tags.
+        UI->getAAMetadata(AATags);
+      } else if (AATags) {
+        UI->getAAMetadata(AATags, /* Merge = */ true);
       }
 
       LoopUses.push_back(UI);
@@ -896,7 +898,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
   SmallVector<PHINode*, 16> NewPHIs;
   SSAUpdater SSA(&NewPHIs);
   LoopPromoter Promoter(SomePtr, LoopUses, SSA, PointerMustAliases, ExitBlocks,
-                        InsertPts, PIC, *CurAST, *LI, DL, Alignment, TBAATag);
+                        InsertPts, PIC, *CurAST, *LI, DL, Alignment, AATags);
 
   // Set up the preheader to have a definition of the value.  It is the live-out
   // value from the preheader that uses in the loop will use.
@@ -905,7 +907,7 @@ void LICM::PromoteAliasSet(AliasSet &AS,
                  Preheader->getTerminator());
   PreheaderLoad->setAlignment(Alignment);
   PreheaderLoad->setDebugLoc(DL);
-  if (TBAATag) PreheaderLoad->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+  if (AATags) PreheaderLoad->setAAMetadata(AATags);
   SSA.AddAvailableValue(Preheader, PreheaderLoad);
 
   // Rewrite all the loads in the loop and remember all the definitions from
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 8c7f253290b..735dd632f01 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1148,10 +1148,12 @@ static void speculatePHINodeLoads(PHINode &PN) {
   PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(),
                                         PN.getName() + ".sroa.speculated");
 
-  // Get the TBAA tag and alignment to use from one of the loads.  It doesn't
+  // Get the AA tags and alignment to use from one of the loads.  It doesn't
   // matter which one we get and if any differ.
   LoadInst *SomeLoad = cast<LoadInst>(PN.user_back());
-  MDNode *TBAATag = SomeLoad->getMetadata(LLVMContext::MD_tbaa);
+
+  AAMDNodes AATags;
+  SomeLoad->getAAMetadata(AATags);
   unsigned Align = SomeLoad->getAlignment();
 
   // Rewrite all loads of the PN to use the new PHI.
@@ -1172,8 +1174,8 @@ static void speculatePHINodeLoads(PHINode &PN) {
         InVal, (PN.getName() + ".sroa.speculate.load." + Pred->getName()));
     ++NumLoadsSpeculated;
     Load->setAlignment(Align);
-    if (TBAATag)
-      Load->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+    if (AATags)
+      Load->setAAMetadata(AATags);
     NewPN->addIncoming(Load, Pred);
   }
 
@@ -1238,12 +1240,15 @@ static void speculateSelectInstLoads(SelectInst &SI) {
         IRB.CreateLoad(FV, LI->getName() + ".sroa.speculate.load.false");
     NumLoadsSpeculated += 2;
 
-    // Transfer alignment and TBAA info if present.
+    // Transfer alignment and AA info if present.
     TL->setAlignment(LI->getAlignment());
     FL->setAlignment(LI->getAlignment());
-    if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa)) {
-      TL->setMetadata(LLVMContext::MD_tbaa, Tag);
-      FL->setMetadata(LLVMContext::MD_tbaa, Tag);
+
+    AAMDNodes Tags;
+    LI->getAAMetadata(Tags);
+    if (Tags) {
+      TL->setAAMetadata(Tags);
+      FL->setAAMetadata(Tags);
     }
 
     Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL,
diff --git a/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index e2a24a7fd4a..579ce13e0b9 100644
--- a/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -1333,12 +1333,15 @@ static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *DL) {
         LoadInst *FalseLoad =
           Builder.CreateLoad(SI->getFalseValue(), LI->getName()+".f");
 
-        // Transfer alignment and TBAA info if present.
+        // Transfer alignment and AA info if present.
         TrueLoad->setAlignment(LI->getAlignment());
         FalseLoad->setAlignment(LI->getAlignment());
-        if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa)) {
-          TrueLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
-          FalseLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+
+        AAMDNodes Tags;
+        LI->getAAMetadata(Tags);
+        if (Tags) {
+          TrueLoad->setAAMetadata(Tags);
+          FalseLoad->setAAMetadata(Tags);
         }
 
         Value *V = Builder.CreateSelect(SI->getCondition(), TrueLoad, FalseLoad);
@@ -1364,10 +1367,12 @@ static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *DL) {
     PHINode *NewPN = PHINode::Create(LoadTy, PN->getNumIncomingValues(),
                                      PN->getName()+".ld", PN);
 
-    // Get the TBAA tag and alignment to use from one of the loads.  It doesn't
+    // Get the AA tags and alignment to use from one of the loads.  It doesn't
     // matter which one we get and if any differ, it doesn't matter.
     LoadInst *SomeLoad = cast<LoadInst>(PN->user_back());
-    MDNode *TBAATag = SomeLoad->getMetadata(LLVMContext::MD_tbaa);
+
+    AAMDNodes AATags;
+    SomeLoad->getAAMetadata(AATags);
     unsigned Align = SomeLoad->getAlignment();
 
     // Rewrite all loads of the PN to use the new PHI.
@@ -1389,7 +1394,7 @@ static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *DL) {
                             PN->getName() + "." + Pred->getName(),
                             Pred->getTerminator());
         Load->setAlignment(Align);
-        if (TBAATag) Load->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+        if (AATags) Load->setAAMetadata(AATags);
       }
 
       NewPN->addIncoming(Load, Pred);