!fixup add LookThroughIntToPtr flag

Author: fhahn

llvm/include/llvm/IR/Value.h

@@ -710,6 +710,10 @@ class Value {
   /// For example, for a value \p ExternalAnalysis might try to calculate a
   /// lower bound. If \p ExternalAnalysis is successful, it should return true.
   ///
+  /// If \p LookThroughIntToPtr is true then this method also looks through
+  /// IntToPtr and PtrToInt constant expressions. The returned pointer may not
+  /// have the same provenance as this value.
+  ///
   /// If this is called on a non-pointer value, it returns 'this' and the
   /// \p Offset is not modified.
   ///
@@ -722,17 +726,19 @@ class Value {
       const DataLayout &DL, APInt &Offset, bool AllowNonInbounds,
       bool AllowInvariantGroup = false,
       function_ref<bool(Value &Value, APInt &Offset)> ExternalAnalysis =
-          nullptr) const;
+          nullptr,
+      bool LookThroughIntToPtr = false) const;
 
   Value *stripAndAccumulateConstantOffsets(
       const DataLayout &DL, APInt &Offset, bool AllowNonInbounds,
       bool AllowInvariantGroup = false,
       function_ref<bool(Value &Value, APInt &Offset)> ExternalAnalysis =
-          nullptr) {
+          nullptr,
+      bool LookThroughIntToPtr = false) {
     return const_cast<Value *>(
         static_cast<const Value *>(this)->stripAndAccumulateConstantOffsets(
-            DL, Offset, AllowNonInbounds, AllowInvariantGroup,
-            ExternalAnalysis));
+            DL, Offset, AllowNonInbounds, AllowInvariantGroup, ExternalAnalysis,
+            LookThroughIntToPtr));
   }
 
   /// This is a wrapper around stripAndAccumulateConstantOffsets with the

llvm/lib/Analysis/ConstantFolding.cpp

@@ -1258,12 +1258,16 @@ Constant *llvm::ConstantFoldCompareInstOperands(
     if (Ops0->getType()->isPointerTy() && !ICmpInst::isSigned(Predicate)) {
       unsigned IndexWidth = DL.getIndexTypeSizeInBits(Ops0->getType());
       APInt Offset0(IndexWidth, 0);
-      bool AllowNonInbounds = ICmpInst::isEquality(Predicate);
+      bool IsEqPred = ICmpInst::isEquality(Predicate);
       Value *Stripped0 = Ops0->stripAndAccumulateConstantOffsets(
-          DL, Offset0, AllowNonInbounds);
+          DL, Offset0, /*AllowNonInbounds=*/IsEqPred,
+          /*AllowInvariantGroup=*/false, /*ExternalAnalysis=*/nullptr,
+          /*LookThroughIntToPtr*/ IsEqPred);
       APInt Offset1(IndexWidth, 0);
       Value *Stripped1 = Ops1->stripAndAccumulateConstantOffsets(
-          DL, Offset1, AllowNonInbounds);
+          DL, Offset1, /*AllowNonInbounds=*/IsEqPred,
+          /*AllowInvariantGroup=*/false, /*ExternalAnalysis=*/nullptr,
+          /*LookThroughIntToPtr*/ IsEqPred);
       if (Stripped0 == Stripped1)
         return ConstantInt::getBool(
             Ops0->getContext(),

llvm/lib/IR/Value.cpp

@@ -714,7 +714,8 @@ const Value *Value::stripPointerCastsForAliasAnalysis() const {
 const Value *Value::stripAndAccumulateConstantOffsets(
     const DataLayout &DL, APInt &Offset, bool AllowNonInbounds,
     bool AllowInvariantGroup,
-    function_ref<bool(Value &, APInt &)> ExternalAnalysis) const {
+    function_ref<bool(Value &, APInt &)> ExternalAnalysis,
+    bool LookThroughIntToPtr) const {
   if (!getType()->isPtrOrPtrVectorTy())
     return this;
 
@@ -777,22 +778,22 @@ const Value *Value::stripAndAccumulateConstantOffsets(
           V = Call->getArgOperand(0);
     } else if (auto *Int2Ptr = dyn_cast<Operator>(V)) {
       // Try to accumulate across (inttoptr (add (ptrtoint p), off)).
-      if (!Int2Ptr || Int2Ptr->getOpcode() != Instruction::IntToPtr ||
+      if (!AllowNonInbounds || !LookThroughIntToPtr || !Int2Ptr ||
+          Int2Ptr->getOpcode() != Instruction::IntToPtr ||
           Int2Ptr->getOperand(0)->getType()->getScalarSizeInBits() != BitWidth)
         return V;
+
       auto *Add = dyn_cast<AddOperator>(Int2Ptr->getOperand(0));
-      if (!AllowNonInbounds || !Add)
+      if (!Add)
         return V;
+
       auto *Ptr2Int = dyn_cast<PtrToIntOperator>(Add->getOperand(0));
       auto *CI = dyn_cast<ConstantInt>(Add->getOperand(1));
       if (!Ptr2Int || !CI)
         return V;
 
-      APInt AddOffset = CI->getValue();
-      if (AddOffset.getSignificantBits() > BitWidth)
-        return V;
-
-      Offset = AddOffset.sextOrTrunc(BitWidth);
+      const APInt &AddOffset = CI->getValue();
+      Offset += AddOffset;
       V = Ptr2Int->getOperand(0);
     }
     assert(V->getType()->isPtrOrPtrVectorTy() && "Unexpected operand type!");

llvm/test/Transforms/InstSimplify/constant-fold-inttoptr-add.ll

@@ -13,8 +13,7 @@ define i1 @known_constexpr_add_eq() {
 
 define i1 @known_constexpr_add_eq_ops_swapped() {
 ; CHECK-LABEL: define i1 @known_constexpr_add_eq_ops_swapped() {
-; CHECK-NEXT:    [[COND:%.*]] = icmp eq ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
-; CHECK-NEXT:    ret i1 [[COND]]
+; CHECK-NEXT:    ret i1 false
 ;
   %cond = icmp eq ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80), inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr)
   ret i1 %cond
@@ -96,3 +95,20 @@ define ptr @return_inttoptr() {
 ;
   ret ptr inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 8) to ptr)
 }
+
+define i1 @known_constexpr_add_nested_1() {
+; CHECK-LABEL: define i1 @known_constexpr_add_nested_1() {
+; CHECK-NEXT:    ret i1 true
+;
+  %cond = icmp eq ptr @glob, inttoptr (i64 add (i64 ptrtoint (ptr getelementptr inbounds nuw (i8, ptr @glob, i64 80) to i64), i64 -80) to ptr)
+  ret i1 %cond
+}
+
+define i1 @known_constexpr_add_nested_2() {
+; CHECK-LABEL: define i1 @known_constexpr_add_nested_2() {
+; CHECK-NEXT:    ret i1 true
+;
+  ;%cond = icmp eq ptr @glob, ptr getelementptr inbounds nuw (i8, ptr inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr), i64 80)
+  %cond = icmp eq ptr @glob, getelementptr inbounds nuw (i8, ptr inttoptr (i64 add (i64 ptrtoint (ptr @glob to i64), i64 -80) to ptr), i64 80)
+  ret i1 %cond
+}