[InstCombine] Support ptrtoaddr of ptrmask fold

For now not trying to share the code with ptrtoint, as there's very
little code.

Also fix IRBuilder::CreatePtrToAddr to actually create a PtrToAddr
instruction...

Author: nikic

llvm/include/llvm/IR/IRBuilder.h

@@ -2191,7 +2191,7 @@ class IRBuilderBase {
                       FMFSource);
   }
   Value *CreatePtrToAddr(Value *V, const Twine &Name = "") {
-    return CreateCast(Instruction::PtrToInt, V,
+    return CreateCast(Instruction::PtrToAddr, V,
                       BB->getDataLayout().getAddressType(V->getType()), Name);
   }
   Value *CreatePtrToInt(Value *V, Type *DestTy,

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -2228,6 +2228,18 @@ Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
 }
 
 Instruction *InstCombinerImpl::visitPtrToAddr(PtrToAddrInst &CI) {
+  Value *SrcOp = CI.getPointerOperand();
+  Type *Ty = CI.getType();
+
+  // (ptrtoaddr (ptrmask P, M))
+  //    -> (and (ptrtoaddr P), M)
+  // This is generally beneficial as `and` is better supported than `ptrmask`.
+  Value *Ptr, *Mask;
+  if (match(SrcOp, m_OneUse(m_Intrinsic<Intrinsic::ptrmask>(m_Value(Ptr),
+                                                            m_Value(Mask)))) &&
+      Mask->getType() == Ty)
+    return BinaryOperator::CreateAnd(Builder.CreatePtrToAddr(Ptr), Mask);
+
   // FIXME: Implement variants of ptrtoint folds.
   return commonCastTransforms(CI);
 }

llvm/test/Transforms/InstCombine/ptrtoaddr.ll

@@ -237,3 +237,27 @@ define ptr addrspace(1) @gep_sub_ptrtoaddr_different_obj_addrsize(ptr addrspace(
   call void @use.i32(i32 %addr)
   ret ptr addrspace(1) %gep
 }
+
+define i64 @ptrtoaddr_of_ptrmask(ptr %p, i64 %mask) {
+; CHECK-LABEL: define i64 @ptrtoaddr_of_ptrmask(
+; CHECK-SAME: ptr [[P:%.*]], i64 [[MASK:%.*]]) {
+; CHECK-NEXT:    [[TMP1:%.*]] = ptrtoaddr ptr [[P]] to i64
+; CHECK-NEXT:    [[ADDR:%.*]] = and i64 [[MASK]], [[TMP1]]
+; CHECK-NEXT:    ret i64 [[ADDR]]
+;
+  %masked = call ptr @llvm.ptrmask(ptr %p, i64 %mask)
+  %addr = ptrtoaddr ptr %masked to i64
+  ret i64 %addr
+}
+
+define i32 @ptrtoaddr_of_ptrmask_addrsize(ptr addrspace(1) %p, i32 %mask) {
+; CHECK-LABEL: define i32 @ptrtoaddr_of_ptrmask_addrsize(
+; CHECK-SAME: ptr addrspace(1) [[P:%.*]], i32 [[MASK:%.*]]) {
+; CHECK-NEXT:    [[TMP1:%.*]] = ptrtoaddr ptr addrspace(1) [[P]] to i32
+; CHECK-NEXT:    [[ADDR:%.*]] = and i32 [[MASK]], [[TMP1]]
+; CHECK-NEXT:    ret i32 [[ADDR]]
+;
+  %masked = call ptr addrspace(1) @llvm.ptrmask(ptr addrspace(1) %p, i32 %mask)
+  %addr = ptrtoaddr ptr addrspace(1) %masked to i32
+  ret i32 %addr
+}