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/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 16365c0..71e9197 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1005,6 +1005,7 @@
case ISD::MERGE_VALUES:
case ISD::EH_RETURN:
case ISD::FRAME_TO_ARGS_OFFSET:
+ case ISD::EH_DWARF_CFA:
case ISD::EH_SJLJ_SETJMP:
case ISD::EH_SJLJ_LONGJMP:
case ISD::EH_SJLJ_SETUP_DISPATCH:
@@ -2782,6 +2783,21 @@
case ISD::FRAME_TO_ARGS_OFFSET:
Results.push_back(DAG.getConstant(0, dl, Node->getValueType(0)));
break;
+ case ISD::EH_DWARF_CFA: {
+ SDValue CfaArg = DAG.getSExtOrTrunc(Node->getOperand(0), dl,
+ TLI.getPointerTy(DAG.getDataLayout()));
+ SDValue Offset = DAG.getNode(ISD::ADD, dl,
+ CfaArg.getValueType(),
+ DAG.getNode(ISD::FRAME_TO_ARGS_OFFSET, dl,
+ CfaArg.getValueType()),
+ CfaArg);
+ SDValue FA = DAG.getNode(
+ ISD::FRAMEADDR, dl, TLI.getPointerTy(DAG.getDataLayout()),
+ DAG.getConstant(0, dl, TLI.getPointerTy(DAG.getDataLayout())));
+ Results.push_back(DAG.getNode(ISD::ADD, dl, FA.getValueType(),
+ FA, Offset));
+ break;
+ }
case ISD::FLT_ROUNDS_:
Results.push_back(DAG.getConstant(1, dl, Node->getValueType(0)));
break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4ea46d5..2455a30 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5017,18 +5017,9 @@
DAG.getMachineFunction().getMMI().setCallsUnwindInit(true);
return nullptr;
case Intrinsic::eh_dwarf_cfa: {
- SDValue CfaArg = DAG.getSExtOrTrunc(getValue(I.getArgOperand(0)), sdl,
- TLI.getPointerTy(DAG.getDataLayout()));
- SDValue Offset = DAG.getNode(ISD::ADD, sdl,
- CfaArg.getValueType(),
- DAG.getNode(ISD::FRAME_TO_ARGS_OFFSET, sdl,
- CfaArg.getValueType()),
- CfaArg);
- SDValue FA = DAG.getNode(
- ISD::FRAMEADDR, sdl, TLI.getPointerTy(DAG.getDataLayout()),
- DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout())));
- setValue(&I, DAG.getNode(ISD::ADD, sdl, FA.getValueType(),
- FA, Offset));
+ setValue(&I, DAG.getNode(ISD::EH_DWARF_CFA, sdl,
+ TLI.getPointerTy(DAG.getDataLayout()),
+ getValue(I.getArgOperand(0))));
return nullptr;
}
case Intrinsic::eh_sjlj_callsite: {
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index ca0dd31..625c6f8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -105,6 +105,7 @@
case ISD::READ_REGISTER: return "READ_REGISTER";
case ISD::WRITE_REGISTER: return "WRITE_REGISTER";
case ISD::FRAME_TO_ARGS_OFFSET: return "FRAME_TO_ARGS_OFFSET";
+ case ISD::EH_DWARF_CFA: return "EH_DWARF_CFA";
case ISD::EH_RETURN: return "EH_RETURN";
case ISD::EH_SJLJ_SETJMP: return "EH_SJLJ_SETJMP";
case ISD::EH_SJLJ_LONGJMP: return "EH_SJLJ_LONGJMP";