Add ptrmask intrinsic

This patch adds a ptrmask intrinsic which allows masking out bits of a
pointer that must be zero when accessing it, because of ABI alignment
requirements or a restriction of the meaningful bits of a pointer
through the data layout.

This avoids doing a ptrtoint/inttoptr round trip in some cases (e.g. tagged
pointers) and allows us to not lose information about the underlying
object.

Reviewers: nlopes, efriedma, hfinkel, sanjoy, jdoerfert, aqjune

Reviewed by: sanjoy, jdoerfert

Differential Revision: https://reviews.llvm.org/D59065

llvm-svn: 368986

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index b4e894a..71d0022 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6859,6 +6859,17 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
     setValue(&I, Val);
     return;
   }
+  case Intrinsic::ptrmask: {
+    SDValue Ptr = getValue(I.getOperand(0));
+    SDValue Const = getValue(I.getOperand(1));
+
+    EVT DestVT =
+        EVT(DAG.getTargetLoweringInfo().getPointerTy(DAG.getDataLayout()));
+
+    setValue(&I, DAG.getNode(ISD::AND, getCurSDLoc(), DestVT, Ptr,
+                             DAG.getZExtOrTrunc(Const, getCurSDLoc(), DestVT)));
+    return;
+  }
   }
 }