Introduce new @llvm.get.dynamic.area.offset.i{32, 64} intrinsics.

The @llvm.get.dynamic.area.offset.* intrinsic family is used to get the offset
from native stack pointer to the address of the most recent dynamic alloca on
the caller's stack. These intrinsics are intendend for use in combination with
@llvm.stacksave and @llvm.restore to get a pointer to the most recent dynamic
alloca. This is useful, for example, for AddressSanitizer's stack unpoisoning
routines.

Patch by Max Ostapenko.

Differential Revision: http://reviews.llvm.org/D14983

llvm-svn: 254404

3 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index c5810525f3c..8238cdeb59c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1213,6 +1213,10 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
   case ISD::STACKSAVE:
     Action = TLI.getOperationAction(Node->getOpcode(), MVT::Other);
     break;
+  case ISD::GET_DYNAMIC_AREA_OFFSET:
+    Action = TLI.getOperationAction(Node->getOpcode(),
+                                    Node->getValueType(0));
+    break;
   case ISD::VAARG:
     Action = TLI.getOperationAction(Node->getOpcode(),
                                     Node->getValueType(0));
@@ -3295,6 +3299,10 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
       Results.push_back(Node->getOperand(0));
     }
     break;
+  case ISD::GET_DYNAMIC_AREA_OFFSET:
+    Results.push_back(DAG.getConstant(0, dl, Node->getValueType(0)));
+    Results.push_back(Results[0].getValue(0));
+    break;
   case ISD::FCOPYSIGN:
     Results.push_back(ExpandFCOPYSIGN(Node));
     break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index d880bcfbdf6..38b8bced239 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4928,6 +4928,21 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     DAG.setRoot(DAG.getNode(ISD::STACKRESTORE, sdl, MVT::Other, getRoot(), Res));
     return nullptr;
   }
+  case Intrinsic::get_dynamic_area_offset: {
+    SDValue Op = getRoot();
+    EVT PtrTy = TLI.getPointerTy(DAG.getDataLayout());
+    EVT ResTy = TLI.getValueType(DAG.getDataLayout(), I.getType());
+    // Result type for @llvm.get.dynamic.area.offset should match PtrTy for
+    // target.
+    if (PtrTy != ResTy)
+      report_fatal_error("Wrong result type for @llvm.get.dynamic.area.offset"
+                         " intrinsic!");
+    Res = DAG.getNode(ISD::GET_DYNAMIC_AREA_OFFSET, sdl, DAG.getVTList(ResTy),
+                      Op);
+    DAG.setRoot(Op);
+    setValue(&I, Res);
+    return nullptr;
+  }
   case Intrinsic::stackprotector: {
     // Emit code into the DAG to store the stack guard onto the stack.
     MachineFunction &MF = DAG.getMachineFunction();
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 195b4849860..a6f9699bb29 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -310,6 +310,7 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::LIFETIME_END:               return "lifetime.end";
   case ISD::GC_TRANSITION_START:        return "gc_transition.start";
   case ISD::GC_TRANSITION_END:          return "gc_transition.end";
+  case ISD::GET_DYNAMIC_AREA_OFFSET:    return "get.dynamic.area.offset";
 
   // Bit manipulation
   case ISD::BITREVERSE:                 return "bitreverse";