labath added inline comments.
================ Comment at: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp:3740 + if (tail_call) + call_inst_pc = low_pc; + else ---------------- vsk wrote: > I think this needs to be `call_inst_pc = low_pc - 1`, see > `DwarfCompileUnit::constructCallSiteEntryDIE` for the rationale, and > `StackFrameList::SynthesizeTailCallFrames` for where we use this information. > The relevant part of the comment from SynthesizeTailCallFrames is: > > "We do not want to subtract 1 from this PC, as it's the actual address of the > tail-calling branch instruction. This address is provided by the compiler via > DW_AT_call_pc." > > In GNU+Dwarf4 mode, that's no longer true, the DW_AT_low_pc is a fake "return > address" for the tail call (really: the address of the instruction after the > tail-calling jump). > > On x86_64, this test doesn't seem to stress this case, but the test breaks on > Darwin/arm64 without the adjustment. Heh, you're right. I should've looked at what the code does instead of just trying to reverse engineer the logic from the output. I've now added the -1. After looking that this code some more, I've come to realize that it's usage of the lack of DW_AT_call_return_pc to indicate a tail call is not correct -- I don't see anything preventing a producer from generating this attribute even for tail calls. I'm going to try refactoring this in another patch to store the tail-call-ness more explicitly. That should also make this part slightly cleaner. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D80519/new/ https://reviews.llvm.org/D80519 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
