[Value] Look through inttoptr (add ..) in accumulateConstantOffsets (#124981)

Look through inttoptr (add (ptrtoint P), C) when accumulating offsets.

Adds a missing fold after
https://github.com/llvm/llvm-project/pull/123518

Alive2 for the tests with changes: https://alive2.llvm.org/ce/z/VvPrzv

PR: https://github.com/llvm/llvm-project/pull/124981

1 files changed, 20 insertions, 1 deletions

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index eddb672..b5a69b9 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/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;
 
@@ -775,6 +776,24 @@ const Value *Value::stripAndAccumulateConstantOffsets(
           V = RV;
         if (AllowInvariantGroup && Call->isLaunderOrStripInvariantGroup())
           V = Call->getArgOperand(0);
+    } else if (auto *Int2Ptr = dyn_cast<Operator>(V)) {
+      // Try to accumulate across (inttoptr (add (ptrtoint p), off)).
+      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 (!Add)
+        return V;
+
+      auto *Ptr2Int = dyn_cast<PtrToIntOperator>(Add->getOperand(0));
+      auto *CI = dyn_cast<ConstantInt>(Add->getOperand(1));
+      if (!Ptr2Int || !CI)
+        return V;
+
+      Offset += CI->getValue();
+      V = Ptr2Int->getOperand(0);
     }
     assert(V->getType()->isPtrOrPtrVectorTy() && "Unexpected operand type!");
   } while (Visited.insert(V).second);