[SelectionDAG] Introduce ISD::PTRADD

llvm/include/llvm/Target/TargetMachine.h

@@ -35,6 +35,7 @@ namespace llvm {
 class AAManager;
 using ModulePassManager = PassManager<Module>;
 
+struct EVT;
 class Function;
 class GlobalValue;
 class MachineModuleInfoWrapperPass;
@@ -469,9 +470,13 @@ class TargetMachine {
   }
 
   /// True if target has some particular form of dealing with pointer arithmetic
-  /// semantics. False if pointer arithmetic should not be preserved for passes
-  /// such as instruction selection, and can fallback to regular arithmetic.
-  virtual bool shouldPreservePtrArith(const Function &F) const { return false; }
+  /// semantics for pointers with the given value type. False if pointer
+  /// arithmetic should not be preserved for passes such as instruction
+  /// selection, and can fallback to regular arithmetic.
+  virtual bool shouldPreservePtrArith(const Function &F,
+                                      const EVT &PtrVT) const {
+    return false;
+  }
 
   /// Create a pass configuration object to be used by addPassToEmitX methods
   /// for generating a pipeline of CodeGen passes.

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -8146,7 +8146,7 @@ SDValue SelectionDAG::getMemBasePlusOffset(SDValue Ptr, SDValue Offset,
   assert(Offset.getValueType().isInteger());
   EVT BasePtrVT = Ptr.getValueType();
   if (!this->getTarget().shouldPreservePtrArith(
-          this->getMachineFunction().getFunction()))
+          this->getMachineFunction().getFunction(), BasePtrVT))
     return getNode(ISD::ADD, DL, BasePtrVT, Ptr, Offset, Flags);
   return getNode(ISD::PTRADD, DL, BasePtrVT, Ptr, Offset, Flags);
 }