SIGSEGV (Address boundary error) in dumpDebugLoc(llvm::DWARFContext&, llvm::DWARFYAML::Data&) ()  #6879

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1. kripken commented on Aug 28, 2024

   

   kripken

   on Aug 28, 2024

   Member

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   Looks like a problem with our DWARF support, which is experimental. It is recommended to use source maps instead for debugging.

   To avoid this problem you can strip debug info, by adding --strip-debug to that command.
2. ArkadySkv commented on Oct 9, 2026

   

   ArkadySkv

   on Oct 9, 2026

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   Fixed by PR #7910 (commit 3f3ed7f6f, "[DWARF] Fix segfault with empty
   dwarf .debug_loc").

   The fix adds a null-CU guard at the top of dumpDebugLoc in
   third_party/llvm-project/dwarf2yaml.cpp:

   auto CUS = DCtx.normal_units();
   if (CUS.empty()) {
     return;
   }
   

   Before this guard, a module whose .debug_loc section contained
   location lists with no associated compile unit would dereference a
   null DWARFCompileUnit* during base-address resolution, producing
   the SIGSEGV reported here.

   Verified on current main: the attached reproducer
   (iot-config-web-dx_bg.wasm) optimizes successfully with

   wasm-opt -Oz iot-config-web-dx_bg.wasm --zero-filled-memory -o out.wasm
   echo "exit: $?"
   

   exits with status 0, and does not crash under gdb. Closing as fixed.
3. kripken

   closed this as completedon Oct 9, 2026