Add ISD::EH_DWARF_CFA, simplify @llvm.eh.dwarf.cfa on Mips, fix on PowerPC
LLVM has an @llvm.eh.dwarf.cfa intrinsic, used to lower the GCC-compatible
__builtin_dwarf_cfa() builtin. As pointed out in PR26761, this is currently
broken on PowerPC (and likely on ARM as well). Currently, @llvm.eh.dwarf.cfa is
lowered using:
ADD(FRAMEADDR, FRAME_TO_ARGS_OFFSET)
where FRAME_TO_ARGS_OFFSET defaults to the constant zero. On x86,
FRAME_TO_ARGS_OFFSET is lowered to 2*SlotSize. This setup, however, does not
work for PowerPC. Because of the way that the stack layout works, the canonical
frame address is not exactly (FRAMEADDR + FRAME_TO_ARGS_OFFSET) on PowerPC
(there is a lower save-area offset as well), so it is not just a matter of
implementing FRAME_TO_ARGS_OFFSET for PowerPC (unless we redefine its
semantics -- We can do that, since it is currently used only for
@llvm.eh.dwarf.cfa lowering, but the better to directly lower the CFA construct
itself (since it can be easily represented as a fixed-offset FrameIndex)). Mips
currently does this, but by using a custom lowering for ADD that specifically
recognizes the (FRAMEADDR, FRAME_TO_ARGS_OFFSET) pattern.
This change introduces a ISD::EH_DWARF_CFA node, which by default expands using
the existing logic, but can be directly lowered by the target. Mips is updated
to use this method (which simplifies its implementation, and I suspect makes it
more robust), and updates PowerPC to do the same.
Fixes PR26761.
Differential Revision: https://reviews.llvm.org/D24038
llvm-svn: 280350
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 09887c3..028f31a 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -344,6 +344,8 @@
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i64 , Custom);
setOperationAction(ISD::GET_DYNAMIC_AREA_OFFSET, MVT::i32, Custom);
setOperationAction(ISD::GET_DYNAMIC_AREA_OFFSET, MVT::i64, Custom);
+ setOperationAction(ISD::EH_DWARF_CFA, MVT::i32, Custom);
+ setOperationAction(ISD::EH_DWARF_CFA, MVT::i64, Custom);
// We want to custom lower some of our intrinsics.
setOperationAction(ISD::INTRINSIC_WO_CHAIN, MVT::Other, Custom);
@@ -6188,6 +6190,17 @@
return DAG.getNode(PPCISD::DYNALLOC, dl, VTs, Ops);
}
+SDValue PPCTargetLowering::LowerEH_DWARF_CFA(SDValue Op,
+ SelectionDAG &DAG) const {
+ MachineFunction &MF = DAG.getMachineFunction();
+
+ bool isPPC64 = Subtarget.isPPC64();
+ EVT PtrVT = getPointerTy(DAG.getDataLayout());
+
+ int FI = MF.getFrameInfo().CreateFixedObject(isPPC64 ? 8 : 4, 0, false);
+ return DAG.getFrameIndex(FI, PtrVT);
+}
+
SDValue PPCTargetLowering::lowerEH_SJLJ_SETJMP(SDValue Op,
SelectionDAG &DAG) const {
SDLoc DL(Op);
@@ -8246,6 +8259,9 @@
case ISD::GET_DYNAMIC_AREA_OFFSET:
return LowerGET_DYNAMIC_AREA_OFFSET(Op, DAG);
+ case ISD::EH_DWARF_CFA:
+ return LowerEH_DWARF_CFA(Op, DAG);
+
case ISD::EH_SJLJ_SETJMP: return lowerEH_SJLJ_SETJMP(Op, DAG);
case ISD::EH_SJLJ_LONGJMP: return lowerEH_SJLJ_LONGJMP(Op, DAG);