path: root/build/build-clang/revert-llvmorg-16-init-9324-g01859da84bad.patch

From 4ebea86ddf20d3f9be3cb363eed3f313591bee66 Mon Sep 17 00:00:00 2001
From: Mike Hommey <mh@glandium.org>
Date: Thu, 3 Nov 2022 13:54:08 +0900
Subject: [PATCH] Revert "[AliasAnalysis] Introduce getModRefInfoMask() as a
 generalization of pointsToConstantMemory()."

This reverts commit 01859da84bad95fd51d6a03b08b60c660e642a4f
for causing https://github.com/llvm/llvm-project/issues/58776
---
 llvm/docs/AliasAnalysis.rst                   | 26 +++-----
 llvm/include/llvm/Analysis/AliasAnalysis.h    | 51 ++++-----------
 .../llvm/Analysis/BasicAliasAnalysis.h        | 12 +---
 .../llvm/Analysis/ObjCARCAliasAnalysis.h      |  4 +-
 .../llvm/Analysis/TypeBasedAliasAnalysis.h    |  4 +-
 llvm/lib/Analysis/AliasAnalysis.cpp           | 63 +++++++++----------
 llvm/lib/Analysis/BasicAliasAnalysis.cpp      | 43 ++++---------
 .../lib/Analysis/MemoryDependenceAnalysis.cpp |  2 +-
 llvm/lib/Analysis/MemorySSA.cpp               |  5 +-
 llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp    | 19 +++---
 llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp  | 14 ++---
 .../lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp | 47 ++++++++++++--
 llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.h  |  4 +-
 llvm/lib/Transforms/IPO/FunctionAttrs.cpp     |  7 +--
 .../InstCombine/InstCombineCalls.cpp          |  4 +-
 .../InstCombineLoadStoreAlloca.cpp            | 33 +++++-----
 llvm/lib/Transforms/Scalar/LICM.cpp           |  2 +-
 .../lib/Transforms/Scalar/LoopPredication.cpp |  2 +-
 llvm/test/Analysis/BasicAA/constant-memory.ll | 14 +++--
 .../InstCombine/memcpy-from-global.ll         |  6 +-
 llvm/test/Transforms/InstCombine/store.ll     |  4 +-
 21 files changed, 168 insertions(+), 198 deletions(-)

diff --git a/llvm/docs/AliasAnalysis.rst b/llvm/docs/AliasAnalysis.rst
index 046dd24d7332..b9a8a3a4eb52 100644
--- a/llvm/docs/AliasAnalysis.rst
+++ b/llvm/docs/AliasAnalysis.rst
@@ -161,24 +161,14 @@ Other useful ``AliasAnalysis`` methods
 Several other tidbits of information are often collected by various alias
 analysis implementations and can be put to good use by various clients.
 
-The ``getModRefInfoMask`` method
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The ``getModRefInfoMask`` method returns a bound on Mod/Ref information for
-the supplied pointer, based on knowledge about whether the pointer points to
-globally-constant memory (for which it returns ``NoModRef``) or
-locally-invariant memory (for which it returns ``Ref``). Globally-constant
-memory includes functions, constant global variables, and the null pointer.
-Locally-invariant memory is memory that we know is invariant for the lifetime
-of its SSA value, but not necessarily for the life of the program: for example,
-the memory pointed to by ``readonly`` ``noalias`` parameters is known-invariant
-for the duration of the corresponding function call. Given Mod/Ref information
-``MRI`` for a memory location ``Loc``, ``MRI`` can be refined with a statement
-like ``MRI &= AA.getModRefInfoMask(Loc);``. Another useful idiom is
-``isModSet(AA.getModRefInfoMask(Loc))``; this checks to see if the given
-location can be modified at all. For convenience, there is also a method
-``pointsToConstantMemory(Loc)``; this is synonymous with
-``isNoModRef(AA.getModRefInfoMask(Loc))``.
+The ``pointsToConstantMemory`` method
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ``pointsToConstantMemory`` method returns true if and only if the analysis
+can prove that the pointer only points to unchanging memory locations
+(functions, constant global variables, and the null pointer).  This information
+can be used to refine mod/ref information: it is impossible for an unchanging
+memory location to be modified.
 
 .. _never access memory or only read memory:
 
diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index 953e15e358f1..1b15d130967a 100644
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -375,9 +375,7 @@ public:
 
   /// Checks whether the given location points to constant memory, or if
   /// \p OrLocal is true whether it points to a local alloca.
-  bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal = false) {
-    return isNoModRef(getModRefInfoMask(Loc, OrLocal));
-  }
+  bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal = false);
 
   /// A convenience wrapper around the primary \c pointsToConstantMemory
   /// interface.
@@ -390,22 +388,6 @@ public:
   /// \name Simple mod/ref information
   /// @{
 
-  /// Returns a bitmask that should be unconditionally applied to the ModRef
-  /// info of a memory location. This allows us to eliminate Mod and/or Ref
-  /// from the ModRef info based on the knowledge that the memory location
-  /// points to constant and/or locally-invariant memory.
-  ///
-  /// If IgnoreLocals is true, then this method returns NoModRef for memory
-  /// that points to a local alloca.
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
-                               bool IgnoreLocals = false);
-
-  /// A convenience wrapper around the primary \c getModRefInfoMask
-  /// interface.
-  ModRefInfo getModRefInfoMask(const Value *P, bool IgnoreLocals = false) {
-    return getModRefInfoMask(MemoryLocation::getBeforeOrAfter(P), IgnoreLocals);
-  }
-
   /// Get the ModRef info associated with a pointer argument of a call. The
   /// result's bits are set to indicate the allowed aliasing ModRef kinds. Note
   /// that these bits do not necessarily account for the overall behavior of
@@ -555,8 +537,6 @@ public:
 
   bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
                               bool OrLocal = false);
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals = false);
   ModRefInfo getModRefInfo(const Instruction *I, const CallBase *Call2,
                            AAQueryInfo &AAQIP);
   ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
@@ -624,10 +604,6 @@ public:
   bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal = false) {
     return AA.pointsToConstantMemory(Loc, AAQI, OrLocal);
   }
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
-                               bool IgnoreLocals = false) {
-    return AA.getModRefInfoMask(Loc, AAQI, IgnoreLocals);
-  }
   ModRefInfo getModRefInfo(const Instruction *I,
                            const std::optional<MemoryLocation> &OptLoc) {
     return AA.getModRefInfo(I, OptLoc, AAQI);
@@ -690,19 +666,16 @@ public:
                             const MemoryLocation &LocB, AAQueryInfo &AAQI,
                             const Instruction *CtxI) = 0;
 
+  /// Checks whether the given location points to constant memory, or if
+  /// \p OrLocal is true whether it points to a local alloca.
+  virtual bool pointsToConstantMemory(const MemoryLocation &Loc,
+                                      AAQueryInfo &AAQI, bool OrLocal) = 0;
+
   /// @}
   //===--------------------------------------------------------------------===//
   /// \name Simple mod/ref information
   /// @{
 
-  /// Returns a bitmask that should be unconditionally applied to the ModRef
-  /// info of a memory location. This allows us to eliminate Mod and/or Ref from
-  /// the ModRef info based on the knowledge that the memory location points to
-  /// constant and/or locally-invariant memory.
-  virtual ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
-                                       AAQueryInfo &AAQI,
-                                       bool IgnoreLocals) = 0;
-
   /// Get the ModRef info associated with a pointer argument of a callsite. The
   /// result's bits are set to indicate the allowed aliasing ModRef kinds. Note
   /// that these bits do not necessarily account for the overall behavior of
@@ -751,9 +724,9 @@ public:
     return Result.alias(LocA, LocB, AAQI, CtxI);
   }
 
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals) override {
-    return Result.getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal) override {
+    return Result.pointsToConstantMemory(Loc, AAQI, OrLocal);
   }
 
   ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) override {
@@ -806,9 +779,9 @@ public:
     return AliasResult::MayAlias;
   }
 
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals) {
-    return ModRefInfo::ModRef;
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal) {
+    return false;
   }
 
   ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) {
diff --git a/llvm/include/llvm/Analysis/BasicAliasAnalysis.h b/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
index a2735f039a01..397692694322 100644
--- a/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/BasicAliasAnalysis.h
@@ -73,15 +73,9 @@ public:
   ModRefInfo getModRefInfo(const CallBase *Call1, const CallBase *Call2,
                            AAQueryInfo &AAQI);
 
-  /// Returns a bitmask that should be unconditionally applied to the ModRef
-  /// info of a memory location. This allows us to eliminate Mod and/or Ref
-  /// from the ModRef info based on the knowledge that the memory location
-  /// points to constant and/or locally-invariant memory.
-  ///
-  /// If IgnoreLocals is true, then this method returns NoModRef for memory
-  /// that points to a local alloca.
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals = false);
+  /// Chases pointers until we find a (constant global) or not.
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal);
 
   /// Get the location associated with a pointer argument of a callsite.
   ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx);
diff --git a/llvm/include/llvm/Analysis/ObjCARCAliasAnalysis.h b/llvm/include/llvm/Analysis/ObjCARCAliasAnalysis.h
index 1a154c648fe6..ef162ece8a32 100644
--- a/llvm/include/llvm/Analysis/ObjCARCAliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/ObjCARCAliasAnalysis.h
@@ -52,8 +52,8 @@ public:
 
   AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
                     AAQueryInfo &AAQI, const Instruction *CtxI);
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals);
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal);
 
   using AAResultBase::getMemoryEffects;
   MemoryEffects getMemoryEffects(const Function *F);
diff --git a/llvm/include/llvm/Analysis/TypeBasedAliasAnalysis.h b/llvm/include/llvm/Analysis/TypeBasedAliasAnalysis.h
index 36dd39c033aa..84a2a6a2fdac 100644
--- a/llvm/include/llvm/Analysis/TypeBasedAliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/TypeBasedAliasAnalysis.h
@@ -40,8 +40,8 @@ public:
 
   AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
                     AAQueryInfo &AAQI, const Instruction *CtxI);
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals);
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal);
 
   MemoryEffects getMemoryEffects(const CallBase *Call, AAQueryInfo &AAQI);
   MemoryEffects getMemoryEffects(const Function *F);
diff --git a/llvm/lib/Analysis/AliasAnalysis.cpp b/llvm/lib/Analysis/AliasAnalysis.cpp
index 9e24f6b87bdb..5e27808cfdb3 100644
--- a/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -146,25 +146,19 @@ AliasResult AAResults::alias(const MemoryLocation &LocA,
   return Result;
 }
 
-ModRefInfo AAResults::getModRefInfoMask(const MemoryLocation &Loc,
-                                        bool IgnoreLocals) {
+bool AAResults::pointsToConstantMemory(const MemoryLocation &Loc,
+                                       bool OrLocal) {
   SimpleAAQueryInfo AAQIP(*this);
-  return getModRefInfoMask(Loc, AAQIP, IgnoreLocals);
+  return pointsToConstantMemory(Loc, AAQIP, OrLocal);
 }
 
-ModRefInfo AAResults::getModRefInfoMask(const MemoryLocation &Loc,
-                                        AAQueryInfo &AAQI, bool IgnoreLocals) {
-  ModRefInfo Result = ModRefInfo::ModRef;
-
-  for (const auto &AA : AAs) {
-    Result &= AA->getModRefInfoMask(Loc, AAQI, IgnoreLocals);
-
-    // Early-exit the moment we reach the bottom of the lattice.
-    if (isNoModRef(Result))
-      return ModRefInfo::NoModRef;
-  }
+bool AAResults::pointsToConstantMemory(const MemoryLocation &Loc,
+                                       AAQueryInfo &AAQI, bool OrLocal) {
+  for (const auto &AA : AAs)
+    if (AA->pointsToConstantMemory(Loc, AAQI, OrLocal))
+      return true;
 
-  return Result;
+  return false;
 }
 
 ModRefInfo AAResults::getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) {
@@ -253,11 +247,10 @@ ModRefInfo AAResults::getModRefInfo(const CallBase *Call,
 
   Result &= ArgMR | OtherMR;
 
-  // Apply the ModRef mask. This ensures that if Loc is a constant memory
-  // location, we take into account the fact that the call definitely could not
+  // If Loc is a constant memory location, the call definitely could not
   // modify the memory location.
-  if (!isNoModRef(Result))
-    Result &= getModRefInfoMask(Loc);
+  if (isModSet(Result) && pointsToConstantMemory(Loc, AAQI, /*OrLocal*/ false))
+    Result &= ModRefInfo::Ref;
 
   return Result;
 }
@@ -495,11 +488,9 @@ ModRefInfo AAResults::getModRefInfo(const StoreInst *S,
     if (AR == AliasResult::NoAlias)
       return ModRefInfo::NoModRef;
 
-    // Examine the ModRef mask. If Mod isn't present, then return NoModRef.
-    // This ensures that if Loc is a constant memory location, we take into
-    // account the fact that the store definitely could not modify the memory
-    // location.
-    if (!isModSet(getModRefInfoMask(Loc)))
+    // If the pointer is a pointer to constant memory, then it could not have
+    // been modified by this store.
+    if (pointsToConstantMemory(Loc, AAQI))
       return ModRefInfo::NoModRef;
   }
 
@@ -510,11 +501,10 @@ ModRefInfo AAResults::getModRefInfo(const StoreInst *S,
 ModRefInfo AAResults::getModRefInfo(const FenceInst *S,
                                     const MemoryLocation &Loc,
                                     AAQueryInfo &AAQI) {
-  // All we know about a fence instruction is what we get from the ModRef
-  // mask: if Loc is a constant memory location, the fence definitely could
-  // not modify it.
-  if (Loc.Ptr)
-    return getModRefInfoMask(Loc);
+  // If we know that the location is a constant memory location, the fence
+  // cannot modify this location.
+  if (Loc.Ptr && pointsToConstantMemory(Loc, AAQI))
+    return ModRefInfo::Ref;
   return ModRefInfo::ModRef;
 }
 
@@ -528,9 +518,10 @@ ModRefInfo AAResults::getModRefInfo(const VAArgInst *V,
     if (AR == AliasResult::NoAlias)
       return ModRefInfo::NoModRef;
 
-    // If the pointer is a pointer to invariant memory, then it could not have
+    // If the pointer is a pointer to constant memory, then it could not have
     // been modified by this va_arg.
-    return getModRefInfoMask(Loc, AAQI);
+    if (pointsToConstantMemory(Loc, AAQI))
+      return ModRefInfo::NoModRef;
   }
 
   // Otherwise, a va_arg reads and writes.
@@ -541,9 +532,10 @@ ModRefInfo AAResults::getModRefInfo(const CatchPadInst *CatchPad,
                                     const MemoryLocation &Loc,
                                     AAQueryInfo &AAQI) {
   if (Loc.Ptr) {
-    // If the pointer is a pointer to invariant memory,
+    // If the pointer is a pointer to constant memory,
     // then it could not have been modified by this catchpad.
-    return getModRefInfoMask(Loc, AAQI);
+    if (pointsToConstantMemory(Loc, AAQI))
+      return ModRefInfo::NoModRef;
   }
 
   // Otherwise, a catchpad reads and writes.
@@ -554,9 +546,10 @@ ModRefInfo AAResults::getModRefInfo(const CatchReturnInst *CatchRet,
                                     const MemoryLocation &Loc,
                                     AAQueryInfo &AAQI) {
   if (Loc.Ptr) {
-    // If the pointer is a pointer to invariant memory,
+    // If the pointer is a pointer to constant memory,
     // then it could not have been modified by this catchpad.
-    return getModRefInfoMask(Loc, AAQI);
+    if (pointsToConstantMemory(Loc, AAQI))
+      return ModRefInfo::NoModRef;
   }
 
   // Otherwise, a catchret reads and writes.
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 1ea1d4196f80..edf46664139e 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -678,46 +678,33 @@ BasicAAResult::DecomposeGEPExpression(const Value *V, const DataLayout &DL,
   return Decomposed;
 }
 
-ModRefInfo BasicAAResult::getModRefInfoMask(const MemoryLocation &Loc,
-                                            AAQueryInfo &AAQI,
-                                            bool IgnoreLocals) {
+/// Returns whether the given pointer value points to memory that is local to
+/// the function, with global constants being considered local to all
+/// functions.
+bool BasicAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                           AAQueryInfo &AAQI, bool OrLocal) {
   assert(Visited.empty() && "Visited must be cleared after use!");
-  auto _ = make_scope_exit([&] { Visited.clear(); });
+  auto _ = make_scope_exit([&]{ Visited.clear(); });
 
   unsigned MaxLookup = 8;
   SmallVector<const Value *, 16> Worklist;
   Worklist.push_back(Loc.Ptr);
-  ModRefInfo Result = ModRefInfo::NoModRef;
-
   do {
     const Value *V = getUnderlyingObject(Worklist.pop_back_val());
     if (!Visited.insert(V).second)
       continue;
 
-    // Ignore allocas if we were instructed to do so.
-    if (IgnoreLocals && isa<AllocaInst>(V))
+    // An alloca instruction defines local memory.
+    if (OrLocal && isa<AllocaInst>(V))
       continue;
 
-    // If the location points to memory that is known to be invariant for
-    // the life of the underlying SSA value, then we can exclude Mod from
-    // the set of valid memory effects.
-    //
-    // An argument that is marked readonly and noalias is known to be
-    // invariant while that function is executing.
-    if (const Argument *Arg = dyn_cast<Argument>(V)) {
-      if (Arg->hasNoAliasAttr() && Arg->onlyReadsMemory()) {
-        Result |= ModRefInfo::Ref;
-        continue;
-      }
-    }
-
-    // A global constant can't be mutated.
+    // A global constant counts as local memory for our purposes.
     if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
       // Note: this doesn't require GV to be "ODR" because it isn't legal for a
       // global to be marked constant in some modules and non-constant in
       // others.  GV may even be a declaration, not a definition.
       if (!GV->isConstant())
-        return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+        return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
       continue;
     }
 
@@ -733,20 +720,16 @@ ModRefInfo BasicAAResult::getModRefInfoMask(const MemoryLocation &Loc,
     if (const PHINode *PN = dyn_cast<PHINode>(V)) {
       // Don't bother inspecting phi nodes with many operands.
       if (PN->getNumIncomingValues() > MaxLookup)
-        return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+        return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
       append_range(Worklist, PN->incoming_values());
       continue;
     }
 
     // Otherwise be conservative.
-    return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+    return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
   } while (!Worklist.empty() && --MaxLookup);
 
-  // If we hit the maximum number of instructions to examine, be conservative.
-  if (!Worklist.empty())
-    return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
-
-  return Result;
+  return Worklist.empty();
 }
 
 static bool isIntrinsicCall(const CallBase *Call, Intrinsic::ID IID) {
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 2340015d6517..6a0b123f0b8f 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -524,7 +524,7 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
       }
 
       // Stores don't alias loads from read-only memory.
-      if (!isModSet(BatchAA.getModRefInfoMask(LoadLoc)))
+      if (BatchAA.pointsToConstantMemory(LoadLoc))
         continue;
 
       // Stores depend on may/must aliased loads.
diff --git a/llvm/lib/Analysis/MemorySSA.cpp b/llvm/lib/Analysis/MemorySSA.cpp
index 0e6a12261e23..c2e2c8d9ec0f 100644
--- a/llvm/lib/Analysis/MemorySSA.cpp
+++ b/llvm/lib/Analysis/MemorySSA.cpp
@@ -375,10 +375,9 @@ static bool isUseTriviallyOptimizableToLiveOnEntry(BatchAAResults &AA,
                                                    const Instruction *I) {
   // If the memory can't be changed, then loads of the memory can't be
   // clobbered.
-  if (auto *LI = dyn_cast<LoadInst>(I)) {
+  if (auto *LI = dyn_cast<LoadInst>(I))
     return I->hasMetadata(LLVMContext::MD_invariant_load) ||
-           !isModSet(AA.getModRefInfoMask(MemoryLocation::get(LI)));
-  }
+           AA.pointsToConstantMemory(MemoryLocation::get(LI));
   return false;
 }
 
diff --git a/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp b/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp
index 1ccf792d2f8c..dd9eae428b0a 100644
--- a/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/ObjCARCAliasAnalysis.cpp
@@ -69,29 +69,28 @@ AliasResult ObjCARCAAResult::alias(const MemoryLocation &LocA,
   return AliasResult::MayAlias;
 }
 
-ModRefInfo ObjCARCAAResult::getModRefInfoMask(const MemoryLocation &Loc,
-                                              AAQueryInfo &AAQI,
-                                              bool IgnoreLocals) {
+bool ObjCARCAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                             AAQueryInfo &AAQI, bool OrLocal) {
   if (!EnableARCOpts)
-    return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+    return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
 
   // First, strip off no-ops, including ObjC-specific no-ops, and try making
   // a precise alias query.
   const Value *S = GetRCIdentityRoot(Loc.Ptr);
-  if (isNoModRef(AAResultBase::getModRefInfoMask(
-          MemoryLocation(S, Loc.Size, Loc.AATags), AAQI, IgnoreLocals)))
-    return ModRefInfo::NoModRef;
+  if (AAResultBase::pointsToConstantMemory(
+          MemoryLocation(S, Loc.Size, Loc.AATags), AAQI, OrLocal))
+    return true;
 
   // If that failed, climb to the underlying object, including climbing through
   // ObjC-specific no-ops, and try making an imprecise alias query.
   const Value *U = GetUnderlyingObjCPtr(S);
   if (U != S)
-    return AAResultBase::getModRefInfoMask(MemoryLocation::getBeforeOrAfter(U),
-                                           AAQI, IgnoreLocals);
+    return AAResultBase::pointsToConstantMemory(
+        MemoryLocation::getBeforeOrAfter(U), AAQI, OrLocal);
 
   // If that failed, fail. We don't need to chain here, since that's covered
   // by the earlier precise query.
-  return ModRefInfo::ModRef;
+  return false;
 }
 
 MemoryEffects ObjCARCAAResult::getMemoryEffects(const Function *F) {
diff --git a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
index 529f3a76d23e..077fbdbe821c 100644
--- a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -385,23 +385,23 @@ AliasResult TypeBasedAAResult::alias(const MemoryLocation &LocA,
   return AliasResult::NoAlias;
 }
 
-ModRefInfo TypeBasedAAResult::getModRefInfoMask(const MemoryLocation &Loc,
-                                                AAQueryInfo &AAQI,
-                                                bool IgnoreLocals) {
+bool TypeBasedAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                               AAQueryInfo &AAQI,
+                                               bool OrLocal) {
   if (!EnableTBAA)
-    return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+    return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
 
   const MDNode *M = Loc.AATags.TBAA;
   if (!M)
-    return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+    return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
 
   // If this is an "immutable" type, we can assume the pointer is pointing
   // to constant memory.
   if ((!isStructPathTBAA(M) && TBAANode(M).isTypeImmutable()) ||
       (isStructPathTBAA(M) && TBAAStructTagNode(M).isTypeImmutable()))
-    return ModRefInfo::NoModRef;
+    return true;
 
-  return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+  return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
 }
 
 MemoryEffects TypeBasedAAResult::getMemoryEffects(const CallBase *Call,
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp
index 8155c895e366..1dd91f2b0be8 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.cpp
@@ -124,19 +124,54 @@ AliasResult AMDGPUAAResult::alias(const MemoryLocation &LocA,
   return AAResultBase::alias(LocA, LocB, AAQI, nullptr);
 }
 
-ModRefInfo AMDGPUAAResult::getModRefInfoMask(const MemoryLocation &Loc,
-                                             AAQueryInfo &AAQI,
-                                             bool IgnoreLocals) {
+bool AMDGPUAAResult::pointsToConstantMemory(const MemoryLocation &Loc,
+                                            AAQueryInfo &AAQI, bool OrLocal) {
   unsigned AS = Loc.Ptr->getType()->getPointerAddressSpace();
   if (AS == AMDGPUAS::CONSTANT_ADDRESS ||
       AS == AMDGPUAS::CONSTANT_ADDRESS_32BIT)
-    return ModRefInfo::NoModRef;
+    return true;
 
   const Value *Base = getUnderlyingObject(Loc.Ptr);
   AS = Base->getType()->getPointerAddressSpace();
   if (AS == AMDGPUAS::CONSTANT_ADDRESS ||
       AS == AMDGPUAS::CONSTANT_ADDRESS_32BIT)
-    return ModRefInfo::NoModRef;
+    return true;
+
+  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(Base)) {
+    if (GV->isConstant())
+      return true;
+  } else if (const Argument *Arg = dyn_cast<Argument>(Base)) {
+    const Function *F = Arg->getParent();
+
+    // Only assume constant memory for arguments on kernels.
+    switch (F->getCallingConv()) {
+    default:
+      return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
+    case CallingConv::AMDGPU_LS:
+    case CallingConv::AMDGPU_HS:
+    case CallingConv::AMDGPU_ES:
+    case CallingConv::AMDGPU_GS:
+    case CallingConv::AMDGPU_VS:
+    case CallingConv::AMDGPU_PS:
+    case CallingConv::AMDGPU_CS:
+    case CallingConv::AMDGPU_KERNEL:
+    case CallingConv::SPIR_KERNEL:
+      break;
+    }
 
-  return AAResultBase::getModRefInfoMask(Loc, AAQI, IgnoreLocals);
+    unsigned ArgNo = Arg->getArgNo();
+    /* On an argument, ReadOnly attribute indicates that the function does
+       not write through this pointer argument, even though it may write
+       to the memory that the pointer points to.
+       On an argument, ReadNone attribute indicates that the function does
+       not dereference that pointer argument, even though it may read or write
+       the memory that the pointer points to if accessed through other pointers.
+     */
+    if (F->hasParamAttribute(ArgNo, Attribute::NoAlias) &&
+        (F->hasParamAttribute(ArgNo, Attribute::ReadNone) ||
+         F->hasParamAttribute(ArgNo, Attribute::ReadOnly))) {
+      return true;
+    }
+  }
+  return AAResultBase::pointsToConstantMemory(Loc, AAQI, OrLocal);
 }
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.h b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.h
index 8ce7000222fa..140ed12a8f6d 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAliasAnalysis.h
@@ -38,8 +38,8 @@ public:
 
   AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
                     AAQueryInfo &AAQI, const Instruction *CtxI);
-  ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
-                               bool IgnoreLocals);
+  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
+                              bool OrLocal);
 };
 
 /// Analysis pass providing a never-invalidated alias analysis result.
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 3f61dbe3354e..cfbceebf66d4 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -138,14 +138,13 @@ static MemoryEffects checkFunctionMemoryAccess(Function &F, bool ThisBody,
     ME |= MemoryEffects::argMemOnly(ModRefInfo::ModRef);
 
   auto AddLocAccess = [&](const MemoryLocation &Loc, ModRefInfo MR) {
-    // Ignore accesses to known-invariant or local memory.
-    MR &= AAR.getModRefInfoMask(Loc, /*IgnoreLocal=*/true);
-    if (isNoModRef(MR))
+    // Ignore accesses to local memory.
+    if (AAR.pointsToConstantMemory(Loc, /*OrLocal=*/true))
       return;
 
     const Value *UO = getUnderlyingObject(Loc.Ptr);
     assert(!isa<AllocaInst>(UO) &&
-           "Should have been handled by getModRefInfoMask()");
+           "Should have been handled by pointsToConstantMemory()");
     if (isa<Argument>(UO)) {
       ME |= MemoryEffects::argMemOnly(MR);
       return;
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index bd3db4534a85..8fad7e8195c8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -135,7 +135,7 @@ Instruction *InstCombinerImpl::SimplifyAnyMemTransfer(AnyMemTransferInst *MI) {
   // If we have a store to a location which is known constant, we can conclude
   // that the store must be storing the constant value (else the memory
   // wouldn't be constant), and this must be a noop.
-  if (!isModSet(AA->getModRefInfoMask(MI->getDest()))) {
+  if (AA->pointsToConstantMemory(MI->getDest())) {
     // Set the size of the copy to 0, it will be deleted on the next iteration.
     MI->setLength(Constant::getNullValue(MI->getLength()->getType()));
     return MI;
@@ -253,7 +253,7 @@ Instruction *InstCombinerImpl::SimplifyAnyMemSet(AnyMemSetInst *MI) {
   // If we have a store to a location which is known constant, we can conclude
   // that the store must be storing the constant value (else the memory
   // wouldn't be constant), and this must be a noop.
-  if (!isModSet(AA->getModRefInfoMask(MI->getDest()))) {
+  if (AA->pointsToConstantMemory(MI->getDest())) {
     // Set the size of the copy to 0, it will be deleted on the next iteration.
     MI->setLength(Constant::getNullValue(MI->getLength()->getType()));
     return MI;
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index c8226ce2816a..8d58241895b5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -36,20 +36,20 @@ static cl::opt<unsigned> MaxCopiedFromConstantUsers(
     cl::desc("Maximum users to visit in copy from constant transform"),
     cl::Hidden);
 
-/// isOnlyCopiedFromConstantMemory - Recursively walk the uses of a (derived)
+/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
 /// pointer to an alloca.  Ignore any reads of the pointer, return false if we
 /// see any stores or other unknown uses.  If we see pointer arithmetic, keep
 /// track of whether it moves the pointer (with IsOffset) but otherwise traverse
 /// the uses.  If we see a memcpy/memmove that targets an unoffseted pointer to
-/// the alloca, and if the source pointer is a pointer to a constant memory
-/// location, we can optimize this.
+/// the alloca, and if the source pointer is a pointer to a constant global, we
+/// can optimize this.
 static bool
 isOnlyCopiedFromConstantMemory(AAResults *AA, AllocaInst *V,
                                MemTransferInst *&TheCopy,
                                SmallVectorImpl<Instruction *> &ToDelete) {
   // We track lifetime intrinsics as we encounter them.  If we decide to go
-  // ahead and replace the value with the memory location, this lets the caller
-  // quickly eliminate the markers.
+  // ahead and replace the value with the global, this lets the caller quickly
+  // eliminate the markers.
 
   using ValueAndIsOffset = PointerIntPair<Value *, 1, bool>;
   SmallVector<ValueAndIsOffset, 32> Worklist;
@@ -150,8 +150,8 @@ isOnlyCopiedFromConstantMemory(AAResults *AA, AllocaInst *V,
       // If the memintrinsic isn't using the alloca as the dest, reject it.
       if (U.getOperandNo() != 0) return false;
 
-      // If the source of the memcpy/move is not constant, reject it.
-      if (isModSet(AA->getModRefInfoMask(MI->getSource())))
+      // If the source of the memcpy/move is not a constant global, reject it.
+      if (!AA->pointsToConstantMemory(MI->getSource()))
         return false;
 
       // Otherwise, the transform is safe.  Remember the copy instruction.
@@ -161,10 +161,9 @@ isOnlyCopiedFromConstantMemory(AAResults *AA, AllocaInst *V,
   return true;
 }
 
-/// isOnlyCopiedFromConstantMemory - Return true if the specified alloca is only
-/// modified by a copy from a constant memory location. If we can prove this, we
-/// can replace any uses of the alloca with uses of the memory location
-/// directly.
+/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
+/// modified by a copy from a constant global.  If we can prove this, we can
+/// replace any uses of the alloca with uses of the global directly.
 static MemTransferInst *
 isOnlyCopiedFromConstantMemory(AAResults *AA,
                                AllocaInst *AI,
@@ -420,11 +419,11 @@ Instruction *InstCombinerImpl::visitAllocaInst(AllocaInst &AI) {
   }
 
   // Check to see if this allocation is only modified by a memcpy/memmove from
-  // a memory location whose alignment is equal to or exceeds that of the
-  // allocation. If this is the case, we can change all users to use the
-  // constant memory location instead.  This is commonly produced by the CFE by
-  // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
-  // is only subsequently read.
+  // a constant whose alignment is equal to or exceeds that of the allocation.
+  // If this is the case, we can change all users to use the constant global
+  // instead.  This is commonly produced by the CFE by constructs like "void
+  // foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A' is only subsequently
+  // read.
   SmallVector<Instruction *, 4> ToDelete;
   if (MemTransferInst *Copy = isOnlyCopiedFromConstantMemory(AA, &AI, ToDelete)) {
     Value *TheSrc = Copy->getSource();
@@ -1401,7 +1400,7 @@ Instruction *InstCombinerImpl::visitStoreInst(StoreInst &SI) {
   // If we have a store to a location which is known constant, we can conclude
   // that the store must be storing the constant value (else the memory
   // wouldn't be constant), and this must be a noop.
-  if (!isModSet(AA->getModRefInfoMask(Ptr)))
+  if (AA->pointsToConstantMemory(Ptr))
     return eraseInstFromFunction(SI);
 
   // Do really simple DSE, to catch cases where there are several consecutive
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index d3739f31bc57..11b96af0a30e 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -1160,7 +1160,7 @@ bool llvm::canSinkOrHoistInst(Instruction &I, AAResults *AA, DominatorTree *DT,
 
     // Loads from constant memory are always safe to move, even if they end up
     // in the same alias set as something that ends up being modified.
-    if (!isModSet(AA->getModRefInfoMask(LI->getOperand(0))))
+    if (AA->pointsToConstantMemory(LI->getOperand(0)))
       return true;
     if (LI->hasMetadata(LLVMContext::MD_invariant_load))
       return true;
diff --git a/llvm/lib/Transforms/Scalar/LoopPredication.cpp b/llvm/lib/Transforms/Scalar/LoopPredication.cpp
index 0492ed5cdb1c..8dd9f0144941 100644
--- a/llvm/lib/Transforms/Scalar/LoopPredication.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopPredication.cpp
@@ -570,7 +570,7 @@ bool LoopPredication::isLoopInvariantValue(const SCEV* S) {
   if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S))
     if (const auto *LI = dyn_cast<LoadInst>(U->getValue()))
       if (LI->isUnordered() && L->hasLoopInvariantOperands(LI))
-        if (!isModSet(AA->getModRefInfoMask(LI->getOperand(0))) ||
+        if (AA->pointsToConstantMemory(LI->getOperand(0)) ||
             LI->hasMetadata(LLVMContext::MD_invariant_load))
           return true;
   return false;
diff --git a/llvm/test/Analysis/BasicAA/constant-memory.ll b/llvm/test/Analysis/BasicAA/constant-memory.ll
index 2b197d6dbc71..6ef875d9358e 100644
--- a/llvm/test/Analysis/BasicAA/constant-memory.ll
+++ b/llvm/test/Analysis/BasicAA/constant-memory.ll
@@ -6,16 +6,18 @@ declare void @dummy()
 
 declare void @foo(ptr)
 
+; FIXME: This could be NoModRef
 ; CHECK-LABEL: Function: basic
-; CHECK: NoModRef: Ptr: i32* @c	<->  call void @dummy()
+; CHECK: Just Ref: Ptr: i32* @c	<->  call void @dummy()
 define void @basic(ptr %p) {
   call void @dummy()
   load i32, ptr @c
   ret void
 }
 
+; FIXME: This could be NoModRef
 ; CHECK-LABEL: Function: recphi
-; CHECK: NoModRef: Ptr: i32* %p	<->  call void @dummy()
+; CHECK: Just Ref: Ptr: i32* %p	<->  call void @dummy()
 define void @recphi() {
 entry:
   br label %loop
@@ -32,20 +34,20 @@ exit:
   ret void
 }
 
-; Tests that readonly noalias implies !Mod.
+; Tests that readonly noalias doesn't imply !Mod yet.
 ;
 ; CHECK-LABEL: Function: readonly_noalias
-; CHECK: Just Ref: Ptr: i32* %p <->  call void @foo(ptr %p)
+; CHECK: Both ModRef: Ptr: i32* %p <->  call void @foo(ptr %p)
 define void @readonly_noalias(ptr readonly noalias %p) {
     call void @foo(ptr %p)
     load i32, ptr %p
     ret void
 }
 
-; Tests that readnone noalias implies !Mod.
+; Tests that readnone noalias doesn't imply !Mod yet.
 ;
 ; CHECK-LABEL: Function: readnone_noalias
-; CHECK: Just Ref: Ptr: i32* %p <->  call void @foo(ptr %p)
+; CHECK: Both ModRef: Ptr: i32* %p <->  call void @foo(ptr %p)
 define void @readnone_noalias(ptr readnone noalias %p) {
     call void @foo(ptr %p)
     load i32, ptr %p
diff --git a/llvm/test/Transforms/InstCombine/memcpy-from-global.ll b/llvm/test/Transforms/InstCombine/memcpy-from-global.ll
index b230c1488f75..cd6dfc4561b9 100644
--- a/llvm/test/Transforms/InstCombine/memcpy-from-global.ll
+++ b/llvm/test/Transforms/InstCombine/memcpy-from-global.ll
@@ -338,10 +338,12 @@ entry:
   ret float %r
 }
 
-; Tests that we can eliminate allocas copied from readonly noalias pointers.
+; Tests that we can't eliminate allocas copied from readonly noalias pointers yet.
 define void @memcpy_from_readonly_noalias(ptr readonly noalias align 8 dereferenceable(124) %arg) {
 ; CHECK-LABEL: @memcpy_from_readonly_noalias(
-; CHECK-NEXT:    call void @bar(ptr nonnull [[ARG:%.*]]) #[[ATTR3]]
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca [[T:%.*]], align 8
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr noundef nonnull align 8 dereferenceable(124) [[ALLOCA]], ptr noundef nonnull align 8 dereferenceable(124) [[ARG:%.*]], i64 124, i1 false)
+; CHECK-NEXT:    call void @bar(ptr nonnull [[ALLOCA]]) #[[ATTR3]]
 ; CHECK-NEXT:    ret void
 ;
   %alloca = alloca %T, align 8
diff --git a/llvm/test/Transforms/InstCombine/store.ll b/llvm/test/Transforms/InstCombine/store.ll
index 95ba64c9e640..7cbe91b44beb 100644
--- a/llvm/test/Transforms/InstCombine/store.ll
+++ b/llvm/test/Transforms/InstCombine/store.ll
@@ -336,10 +336,12 @@ define void @store_to_constant() {
   ret void
 }
 
-; Delete stores to readonly noalias pointers.
+; We can't delete stores to readonly noalias pointers yet.
 define void @store_to_readonly_noalias(ptr readonly noalias %0) {
 ; CHECK-LABEL: @store_to_readonly_noalias(
+; CHECK-NEXT:    store i32 3, ptr [[TMP0:%.*]], align 4
 ; CHECK-NEXT:    ret void
+;
   store i32 3, ptr %0, align 4
   ret void
 }
-- 
2.38.1.1.g6d9df9d320