[WinEH] Add localaddress intrinsic instead of using frameaddress

Clang uses this for SEH finally. The new intrinsic will produce the
right value when stack realignment is required.

llvm-svn: 241643

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1b37912cf61..cc9374450ce 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -15737,6 +15737,19 @@ static SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, const X86Subtarget *Subtarget
           "llvm.x86.seh.recoverfp must take a function as the first argument");
     return recoverFramePointer(DAG, Fn, IncomingFPOp);
   }
+
+  case Intrinsic::localaddress: {
+    // Returns one of the stack, base, or frame pointer registers, depending on
+    // which is used to reference local variables.
+    MachineFunction &MF = DAG.getMachineFunction();
+    const X86RegisterInfo *RegInfo = Subtarget->getRegisterInfo();
+    unsigned Reg;
+    if (RegInfo->hasBasePointer(MF))
+      Reg = RegInfo->getBaseRegister();
+    else // This function handles the SP or FP case.
+      Reg = RegInfo->getPtrSizedFrameRegister(MF);
+    return DAG.getCopyFromReg(DAG.getEntryNode(), dl, Reg, VT);
+  }
   }
 }