[PATCH] [SEH] Add new intrinsics for recovering and restoring parent frames

[David Majnemer]

LGTM with comments addressed.


================
Comment at: lib/Target/X86/X86ISelLowering.cpp:15019
@@ +15018,3 @@
+  default:
+    llvm_unreachable("can only recover FP for MSVC EH personality functions");
+  case EHPersonality::MSVC_X86SEH: RegNodeSize = 24; break;
----------------
Maybe make this a fatal error.

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:15486-15491
@@ -15443,1 +15485,8 @@
+
+  case Intrinsic::x86_seh_recoverfp: {
+    SDValue FnOp = Op.getOperand(1);
+    SDValue IncomingFPOp = Op.getOperand(2);
+    auto *Fn = cast<Function>(cast<GlobalAddressSDNode>(FnOp)->getGlobal());
+    return recoverFramePointer(DAG, Fn, IncomingFPOp);
+  }
   }
----------------
Does somebody need to make sure the argument is pointing at a function? (verifer or backend fatal error or somesuch).

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:15704
@@ -15655,1 +15703,3 @@
+                                    SelectionDAG &DAG) {
+  //llvm::errs() << "LowerSEHRESTOREFRAME\n";
   MachineFunction &MF = DAG.getMachineFunction();
----------------
Dead code?

http://reviews.llvm.org/D10848

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