Wrong DWARF source file path for system libraries #20775
Description
I recently bumped emscripten version and I noticed source map is not working for system libraries.
After bisecting, it seems the commit 53bb231 introduces the source map failure.
To point out the DWARF entry for __trap.c in libcompiler_rt.a, DW_AT_name should be /emsdk/emscripten/system/lib/compiler-rt/__trap.c or system/lib/compiler-rt/__trap.c, but it actually points to ../../../system/lib/compiler-rt/__trap.c
Expected behavior (before 53bb231):
$ llvm-dwarfdump -debug-info -debug-line --recurse-depth=0 emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a
emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a(__trap.o): file format WASM
.debug_info contents:
0x00000000: Compile Unit: length = 0x0000003a, format = DWARF32, version = 0x0004, abbr_offset = 0x0000, addr_size = 0x04 (next unit at 0x0000003e)
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("clang version 17.0.0 (https://github.com/llvm/llvm-project a8cbd27d1f238e104a5d5ca345d93bc1f4d4ab1f)")
DW_AT_language (DW_LANG_C11)
DW_AT_name ("/emsdk/emscripten/system/lib/compiler-rt/__trap.c")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/emsdk/emscripten")
Actual behavior (after 53bb231):
$ llvm-dwarfdump -debug-info -debug-line --recurse-depth=0 emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a
emscripten/cache/sysroot/lib/wasm32-emscripten/libcompiler_rt.a(__trap.o): file format WASM
.debug_info contents:
0x00000000: Compile Unit: length = 0x0000003a, format = DWARF32, version = 0x0004, abbr_offset = 0x0000, addr_size = 0x04 (next unit at 0x0000003e)
0x0000000b: DW_TAG_compile_unit
DW_AT_producer ("clang version 17.0.0 (https://github.com/llvm/llvm-project a8cbd27d1f238e104a5d5ca345d93bc1f4d4ab1f)")
DW_AT_language (DW_LANG_C11)
DW_AT_name ("../../../system/lib/compiler-rt/__trap.c")
DW_AT_stmt_list (0x00000000)
DW_AT_comp_dir ("/emsdk/emscripten")