return DAG.getNode(X86ISD::SELECT, dl, VT, IMask, Op, PreservedSrc);
}
+/// When the 32-bit MSVC runtime transfers control to us, either to an outlined
+/// function or when returning to a parent frame after catching an exception, we
+/// recover the parent frame pointer by doing arithmetic on the incoming EBP.
+/// Here's the math:
+/// RegNodeBase = EntryEBP - RegNodeSize
+/// ParentFP = RegNodeBase - RegNodeFrameOffset
+/// Subtracting RegNodeSize takes us to the offset of the registration node, and
+/// subtracting the offset (negative on x86) takes us back to the parent FP.
+static SDValue recoverFramePointer(SelectionDAG &DAG, const Function *Fn,
+ SDValue EntryEBP) {
+ MachineFunction &MF = DAG.getMachineFunction();
+ SDLoc dl;
+
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ MVT PtrVT = TLI.getPointerTy();
+
+ // The RegNodeSize is 6 32-bit words for SEH and 4 for C++ EH. See
+ // WinEHStatePass for the full struct definition.
+ int RegNodeSize;
+ switch (classifyEHPersonality(Fn->getPersonalityFn())) {
+ default:
+ report_fatal_error("can only recover FP for MSVC EH personality functions");
+ case EHPersonality::MSVC_X86SEH: RegNodeSize = 24; break;
+ case EHPersonality::MSVC_CXX: RegNodeSize = 16; break;
+ }
+
+ // Get an MCSymbol that will ultimately resolve to the frame offset of the EH
+ // registration.
+ MCSymbol *OffsetSym =
+ MF.getMMI().getContext().getOrCreateParentFrameOffsetSymbol(
+ GlobalValue::getRealLinkageName(Fn->getName()));
+ SDValue OffsetSymVal = DAG.getMCSymbol(OffsetSym, PtrVT);
+ SDValue RegNodeFrameOffset =
+ DAG.getNode(ISD::FRAME_ALLOC_RECOVER, dl, PtrVT, OffsetSymVal);
+
+ // RegNodeBase = EntryEBP - RegNodeSize
+ // ParentFP = RegNodeBase - RegNodeFrameOffset
+ SDValue RegNodeBase = DAG.getNode(ISD::SUB, dl, PtrVT, EntryEBP,
+ DAG.getConstant(RegNodeSize, dl, PtrVT));
+ return DAG.getNode(ISD::SUB, dl, PtrVT, RegNodeBase, RegNodeFrameOffset);
+}
+
static SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, const X86Subtarget *Subtarget,
SelectionDAG &DAG) {
SDLoc dl(Op);
SDValue Result = DAG.getMCSymbol(LSDASym, VT);
return DAG.getNode(X86ISD::Wrapper, dl, VT, Result);
}
+
+ case Intrinsic::x86_seh_recoverfp: {
+ SDValue FnOp = Op.getOperand(1);
+ SDValue IncomingFPOp = Op.getOperand(2);
+ GlobalAddressSDNode *GSD = dyn_cast<GlobalAddressSDNode>(FnOp);
+ auto *Fn = dyn_cast_or_null<Function>(GSD ? GSD->getGlobal() : nullptr);
+ if (!Fn)
+ report_fatal_error(
+ "llvm.x86.seh.recoverfp must take a function as the first argument");
+ return recoverFramePointer(DAG, Fn, IncomingFPOp);
+ }
}
}
return DAG.getMergeValues(Results, DL);
}
-static SDValue LowerEXCEPTIONINFO(SDValue Op, const X86Subtarget *Subtarget,
- SelectionDAG &DAG) {
+static SDValue LowerSEHRESTOREFRAME(SDValue Op, const X86Subtarget *Subtarget,
+ SelectionDAG &DAG) {
MachineFunction &MF = DAG.getMachineFunction();
SDLoc dl(Op);
- SDValue FnOp = Op.getOperand(2);
- SDValue FPOp = Op.getOperand(3);
+ SDValue Chain = Op.getOperand(0);
- // Compute the symbol for the parent EH registration. We know it'll get
- // emitted later.
- auto *Fn = cast<Function>(cast<GlobalAddressSDNode>(FnOp)->getGlobal());
- MCSymbol *ParentFrameSym =
- MF.getMMI().getContext().getOrCreateParentFrameOffsetSymbol(
- GlobalValue::getRealLinkageName(Fn->getName()));
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ MVT VT = TLI.getPointerTy();
- // Create a TargetExternalSymbol for the label to avoid any target lowering
- // that would make this PC relative.
- MVT PtrVT = Op.getSimpleValueType();
- SDValue OffsetSym = DAG.getMCSymbol(ParentFrameSym, PtrVT);
- SDValue OffsetVal =
- DAG.getNode(ISD::FRAME_ALLOC_RECOVER, dl, PtrVT, OffsetSym);
+ const X86RegisterInfo *RegInfo = Subtarget->getRegisterInfo();
+ unsigned FrameReg =
+ RegInfo->getPtrSizedFrameRegister(DAG.getMachineFunction());
+ unsigned SPReg = RegInfo->getStackRegister();
- // Add the offset to the FP.
- SDValue Add = DAG.getNode(ISD::ADD, dl, PtrVT, FPOp, OffsetVal);
+ // Get incoming EBP.
+ SDValue IncomingEBP =
+ DAG.getCopyFromReg(Chain, dl, FrameReg, VT);
- // Load the second field of the struct, which is 4 bytes in. See
- // WinEHStatePass for more info.
- Add = DAG.getNode(ISD::ADD, dl, PtrVT, Add, DAG.getConstant(4, dl, PtrVT));
- return DAG.getLoad(PtrVT, dl, DAG.getEntryNode(), Add, MachinePointerInfo(),
- false, false, false, 0);
+ // Load [EBP-24] into SP.
+ SDValue SPAddr =
+ DAG.getNode(ISD::ADD, dl, VT, IncomingEBP, DAG.getConstant(-24, dl, VT));
+ SDValue NewSP =
+ DAG.getLoad(VT, dl, Chain, SPAddr, MachinePointerInfo(), false, false,
+ false, VT.getScalarSizeInBits() / 8);
+ Chain = DAG.getCopyToReg(Chain, dl, SPReg, NewSP);
+
+ // FIXME: Restore the base pointer in case of stack realignment!
+
+ // Adjust EBP to point back to the original frame position.
+ SDValue NewFP = recoverFramePointer(DAG, MF.getFunction(), IncomingEBP);
+ Chain = DAG.getCopyToReg(Chain, dl, FrameReg, NewFP);
+ return Chain;
}
static SDValue LowerINTRINSIC_W_CHAIN(SDValue Op, const X86Subtarget *Subtarget,
const IntrinsicData* IntrData = getIntrinsicWithChain(IntNo);
if (!IntrData) {
- if (IntNo == Intrinsic::x86_seh_exceptioninfo)
- return LowerEXCEPTIONINFO(Op, Subtarget, DAG);
+ if (IntNo == llvm::Intrinsic::x86_seh_restoreframe)
+ return LowerSEHRESTOREFRAME(Op, Subtarget, DAG);
return SDValue();
}
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