Improve objcopy detection #71742
Improve objcopy detection #71742
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Tagging subscribers to this area: @hoyosjs Issue DetailsSee #71270 (comment) Up until recently (#71446), we were using binutils' objcopy on Linux. We should fallback to that if llvm-objcopy provided by selected (older) toolchain does not meet the requirement.
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| OUTPUT_VARIABLE OBJCOPY_HELP_OUTPUT | ||
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| if(CLR_CMAKE_TARGET_ANDROID) |
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@jkotas, I have not changed anything for NativeAOT, since there we anyway require recent versions of llvm / clang (and only use objcopy when user explicitly sets -p:StripSymbols=true). |
| endif() | ||
| # if llvm-objcopy does not support --only-keep-debug argument, try to locate binutils' objcopy | ||
| if (CMAKE_C_COMPILER_ID MATCHES "Clang" AND NOT "${OBJCOPY_HELP_OUTPUT}" MATCHES "--only-keep-debug") | ||
| set(TOOLSET_PREFIX "") |
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llvm also has a only-keep-debug flag, only with one dash though. Any reason to favor binutils over llvm's and just adjusting the flag?
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My test was:
$ docker run -it ubuntu:18.04
# inside the container, install different versions
$ apt update; apt install -y llvm-6 llvm-7 llvm-8 llvm-9 llvm-10
# test for only-keep-debug
# v6 - desired argument is unsupported
$ llvm-objcopy-6.0 --help | grep only-keep-debug
# nothing found
# v7 - supported with single hyphen but is a no-op
$ llvm-objcopy-7 --help | grep only-keep-debug
-only-keep-debug Currently ignored. Only for compaitability with GNU objcopy.
# v8 - same as v7
$ llvm-objcopy-8 --help | grep only-keep-debug
-only-keep-debug Currently ignored. Only for compatibility with GNU objcopy.
# v9 - supported with double hyphen
$ llvm-objcopy-9 --help | grep only-keep-debug
--only-keep-debug Clear sections that would not be stripped by --strip-debug. Currently only implemented for COFF.
# v10 - same as v9
$ llvm-objcopy-10 --help | grep only-keep-debug
--only-keep-debug Produce a debug file as the output that only preserves contents of sections useful for debugging purposesWe want only-keep-debug for consistent output; avoid binary size bloat and avoid repeating issues like #49081. Therefore, we fallback to binutils' objcopy when llvm-objcopy is incapable of stripping the symbols. As you can see above, versions of llvm-objcopy which support double hyphened argument provide non-nop functionality.
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Then this is the right fix. Thanks!
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Failure is #70450 |
Unblocks #71725. Followup: #71742 Prior to #71742, we were calling `locate_toolchain_exec` once per tool. Calling it twice with different prefix gives us the old result, which is something we don't want (we only call this local function a few times in this file, and each time for intention to "lookup" the executable).
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See #71270 (comment)
Up until recently (#71446), we were using binutils' objcopy on Linux. We should fallback to that if llvm-objcopy provided by selected (older) toolchain does not meet the requirement.