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[ORC] Update ELF debugger support plugin to use AllocActions #167866

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Merged
merged 3 commits into from
Nov 17, 2025
Merged

[ORC] Update ELF debugger support plugin to use AllocActions #167866

merged 3 commits into from
Nov 17, 2025

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@weliveindetail weliveindetail commented Nov 13, 2025 •
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The DebugObjectManagerPlugin implements debugger support for ELF platforms with the GDB JIT Interface. It emits a separate debug object allocation in addition to the LinkGraph's own allocation. This used to happen in the plugin's notifyEmitted() callback, i.e. after the LinkGraph's allocation was finalized. In the meantime, it had to block finalization of the corresponding materialization unit to make sure that the debugger can register the object before the code runs.

This patch switches the plugin to use an allocation action instead. We can remove the notifyEmitted() hook and implement all steps as JITLink passes:

  1. We keep fixing up section load addresses in PostAllocationPasses
  2. We now emit the debug object already in PreFixupPasses, i.e. before the LinkGraph's allocation is finalized. This is great, because it can run in parallel to the LinkGraph's link phase 3.
  3. We await the finalization of the debug object in PostFixupPasses and run the GDB JIT Interface registration in an AllocAction when finalizing the LinkGraph's allocation.

Main benefits are:

  • plugin is ported to the new AllocAction approach
  • we save at least one RPC round-trip
  • concurrent emission of the debug object reduces wall-time
  • once this landed, we can drop EPCDebugObjectRegistrar

This PR implements the basic switch. I want to add some more improvements to the plugin in a follow-up (mostly NFC then).

@weliveindetail weliveindetail mentioned this pull request Nov 13, 2025
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weliveindetail commented Nov 14, 2025

FYI: the Windows build failed with an unrelated error

2025-11-13T18:23:06.0717371Z [10620/11138] Linking CXX executable bin\mlir-capi-pass-test.exe
2025-11-13T18:23:06.0718013Z FAILED: [code=4294967295] bin/mlir-capi-pass-test.exe 
2025-11-13T18:23:06.0728799Z lld-link: error: undefined symbol: void __cdecl mlir::ptr::registerConvertPtrToLLVMInterface(class mlir::DialectRegistry &)
2025-11-13T18:23:06.0730811Z >>> referenced by MLIRRegisterAllExtensions.lib(RegisterAllExtensions.cpp.obj):(void __cdecl mlir::registerAllExtensions(class mlir::DialectRegistry &))

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lhames commented Nov 16, 2025

If we switch to a dealloc action for deallocation I think that would simplify this a lot further: At that point DebugObjectManagerPlugin doesn't need to track the resources at all since they'll be covered by the actions attached to the memory allocation.

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weliveindetail commented Nov 16, 2025

Thanks for the feedback. Yes, exactly! I have a patch for it already: weliveindetail@2cf880f, but there are 2 open issues. I will sort it out into PRs next week. I think it's good to review in isolation.

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lhames approved these changes Nov 17, 2025
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Thanks for the feedback. Yes, exactly! I have a patch for it already: weliveindetail@2cf880f, but there are 2 open issues. I will sort it out into PRs next week. I think it's good to review in isolation.

LGTM. Thanks @weliveindetail -- I look forward to checking out the upcoming PRs too. :)

@weliveindetail weliveindetail merged commit 4268e67 into llvm:main Nov 17, 2025
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llvm-ci commented Nov 17, 2025

LLVM Buildbot has detected a new failure on builder llvm-clang-x86_64-gcc-ubuntu running on sie-linux-worker3 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/174/builds/27575

Here is the relevant piece of the build log for the reference 
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'SanitizerCommon-asan-x86_64-Linux :: Linux/soft_rss_limit_mb_test.cpp' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/./bin/clang  --driver-mode=g++ -gline-tables-only -fsanitize=address  -m64 -funwind-tables  -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test -ldl -O2 /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -o /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
# executed command: /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/./bin/clang --driver-mode=g++ -gline-tables-only -fsanitize=address -m64 -funwind-tables -I/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test -ldl -O2 /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -o /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
# note: command had no output on stdout or stderr
# RUN: at line 5
env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=1      /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp 2>&1 | FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_1
# executed command: env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=1 /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
# note: command had no output on stdout or stderr
# executed command: FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_1
# note: command had no output on stdout or stderr
# RUN: at line 6
env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=0 not  /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp 2>&1 | FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_0 --implicit-check-not="returned null"
# executed command: env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=0 not /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
# note: command had no output on stdout or stderr
# executed command: FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_0 '--implicit-check-not=returned null'
# note: command had no output on stdout or stderr
# RUN: at line 10
env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=0:can_use_proc_maps_statm=0 not  /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp 2>&1 | FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_0 --implicit-check-not="returned null"
# executed command: env ASAN_OPTIONS=soft_rss_limit_mb=220:quarantine_size=1:allocator_may_return_null=0:can_use_proc_maps_statm=0 not /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/build/runtimes/runtimes-bins/compiler-rt/test/sanitizer_common/asan-x86_64-Linux/Linux/Output/soft_rss_limit_mb_test.cpp.tmp
# note: command had no output on stdout or stderr
# executed command: FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp -check-prefix=CHECK_MAY_RETURN_0 '--implicit-check-not=returned null'
# .---command stderr------------
# | �[1m/home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp:72:24: �[0m�[0;1;31merror: �[0m�[1mCHECK_MAY_RETURN_0: expected string not found in input
�[0m# | �[1m�[0m// CHECK_MAY_RETURN_0: Some of the malloc calls returned non-null:
# | �[0;1;32m                       ^
�[0m# | �[0;1;32m�[0m�[1m<stdin>:1:24: �[0m�[0;1;30mnote: �[0m�[1mscanning from here
�[0m# | �[1m�[0m[0] allocating 32 times
# | �[0;1;32m                       ^
�[0m# | �[0;1;32m�[0m�[1m<stdin>:10:55: �[0m�[0;1;30mnote: �[0m�[1mpossible intended match here
�[0m# | �[1m�[0m==1041317==HINT: if you don't care about these errors you may set allocator_may_return_null=1
# | �[0;1;32m                                                      ^
�[0m# | �[0;1;32m�[0m
# | Input file: <stdin>
# | Check file: /home/buildbot/buildbot-root/llvm-clang-x86_64-gcc-ubuntu/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Linux/soft_rss_limit_mb_test.cpp
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# | �[1m�[0m�[0;1;30m            1: �[0m�[1m�[0;1;46m[0] �[0mallocating 32 times�[0;1;46m �[0m
# | �[0;1;32mcheck:71           ^~~~~~~~~~~~~~~~~~~
�[0m# | �[0;1;32m�[0m�[0;1;32mnot:imp1       X~~~
�[0m# | �[0;1;32m�[0m�[0;1;31mcheck:72'0                            X error: no match found
�[0m# | �[0;1;31m�[0m�[0;1;30m            2: �[0m�[1m�[0;1;46m [0] �[0m
# | �[0;1;31mcheck:72'0     ~~~~~
...

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