Re: [PATCH v4 1/4] perf libdw: Find the CU by iterating all CUs when aranges are missing

[sashiko-bot@kernel.org]

> libdw__addr2line() finds the CU with dwfl_module_getsrc() and
> dwfl_module_addrdie(), which use dwarf_getaranges(). In elfutils 0.190
> this only reads .debug_aranges, which can be partial. For example, when
> Perf is built with LLVM=1, clang doesn't emit .debug_aranges by default
> so the lookup then fails and no source lines are found for most of the
> Perf binary.
> 
> This used to be hidden by falling back to the next addr2line style, but
> now missing information stops the fallback since commit (62d7cdc8d587
> "perf libdw: Optimize fallback logic for missing DWARF").
> 
> find_cu_die() in annotate-data.c already handles partial aranges by
> iterating all CUs in .debug_info and checking them with dwarf_haspc().
> Move it to dwarf-aux.c, then look up the line in that CU with
> dwarf_getsrc_die() and use the same CU for unwinding inlines. While
> [ ... ]
>   ---- end(-1) ----
>    79: test addr2line inline unwinding : FAILED!
> 
> Fixes: 88c51002d06f ("perf addr2line: Add a libdw implementation")
> Signed-off-by: James Clark <james.clark@linaro.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261109-james-perf-test-fixes-v4-0-355ee6b81917@linaro.org?part=1