3 files changed, 25 insertions, 3 deletions
diff --git a/llvm/include/llvm/IR/Value.h b/llvm/include/llvm/IR/Value.h
index d0de008db26..3f8caa668e5 100644
--- a/llvm/include/llvm/IR/Value.h
+++ b/llvm/include/llvm/IR/Value.h
@@ -493,7 +493,7 @@ public:
   /// swifterror attribute.
   bool isSwiftError() const;
 
-  /// Strip off pointer casts, all-zero GEPs, and aliases.
+  /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases.
   ///
   /// Returns the original uncasted value.  If this is called on a non-pointer
   /// value, it returns 'this'.
@@ -503,6 +503,17 @@ public:
                          static_cast<const Value *>(this)->stripPointerCasts());
   }
 
+  /// Strip off pointer casts, all-zero GEPs, address space casts, and aliases
+  /// but ensures the representation of the result stays the same.
+  ///
+  /// Returns the original uncasted value with the same representation. If this
+  /// is called on a non-pointer value, it returns 'this'.
+  const Value *stripPointerCastsSameRepresentation() const;
+  Value *stripPointerCastsSameRepresentation() {
+    return const_cast<Value *>(static_cast<const Value *>(this)
+                                   ->stripPointerCastsSameRepresentation());
+  }
+
   /// Strip off pointer casts, all-zero GEPs, aliases and invariant group
   /// info.
   ///
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 53e9f49a571..542ff709d47 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1803,7 +1803,7 @@ LazyValueInfo::getPredicateAt(unsigned Pred, Value *V, Constant *C,
   // through would still be correct.
   const DataLayout &DL = CxtI->getModule()->getDataLayout();
   if (V->getType()->isPointerTy() && C->isNullValue() &&
-      isKnownNonZero(V->stripPointerCasts(), DL)) {
+      isKnownNonZero(V->stripPointerCastsSameRepresentation(), DL)) {
     if (Pred == ICmpInst::ICMP_EQ)
       return LazyValueInfo::False;
     else if (Pred == ICmpInst::ICMP_NE)
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index cf32a66c901..9e0a43ce1e3 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -460,6 +460,7 @@ namespace {
 enum PointerStripKind {
   PSK_ZeroIndices,
   PSK_ZeroIndicesAndAliases,
+  PSK_ZeroIndicesAndAliasesSameRepresentation,
   PSK_ZeroIndicesAndAliasesAndInvariantGroups,
   PSK_InBoundsConstantIndices,
   PSK_InBounds
@@ -479,6 +480,7 @@ static const Value *stripPointerCastsAndOffsets(const Value *V) {
     if (auto *GEP = dyn_cast<GEPOperator>(V)) {
       switch (StripKind) {
       case PSK_ZeroIndicesAndAliases:
+      case PSK_ZeroIndicesAndAliasesSameRepresentation:
       case PSK_ZeroIndicesAndAliasesAndInvariantGroups:
       case PSK_ZeroIndices:
         if (!GEP->hasAllZeroIndices())
@@ -494,8 +496,12 @@ static const Value *stripPointerCastsAndOffsets(const Value *V) {
         break;
       }
       V = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(V) == Instruction::BitCast ||
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
+      V = cast<Operator>(V)->getOperand(0);
+    } else if (StripKind != PSK_ZeroIndicesAndAliasesSameRepresentation &&
                Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
+      // TODO: If we know an address space cast will not change the
+      //       representation we could look through it here as well.
       V = cast<Operator>(V)->getOperand(0);
     } else if (auto *GA = dyn_cast<GlobalAlias>(V)) {
       if (StripKind == PSK_ZeroIndices || GA->isInterposable())
@@ -530,6 +536,11 @@ const Value *Value::stripPointerCasts() const {
   return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
 }
 
+const Value *Value::stripPointerCastsSameRepresentation() const {
+  return stripPointerCastsAndOffsets<
+      PSK_ZeroIndicesAndAliasesSameRepresentation>(this);
+}
+
 const Value *Value::stripPointerCastsNoFollowAliases() const {
   return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
 }