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Diffstat (limited to 'docs/OptBisect.rst')
| -rw-r--r-- | docs/OptBisect.rst | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/docs/OptBisect.rst b/docs/OptBisect.rst index e9f1c2541c9c0..5a216d419a641 100644 --- a/docs/OptBisect.rst +++ b/docs/OptBisect.rst @@ -60,11 +60,14 @@ like this: clang -O2 -mllvm -opt-bisect-limit=256 my_file.c The -opt-bisect-limit option may also be applied to link-time optimizations by -using a prefix to indicate that this is a plug-in option for the linker. The +using a prefix to indicate that this is a plug-in option for the linker. The following syntax will set a bisect limit for LTO transformations: :: + # When using lld, or ld64 (macOS) + clang -flto -Wl,-mllvm,-opt-bisect-limit=256 my_file.o my_other_file.o + # When using Gold clang -flto -Wl,-plugin-opt,-opt-bisect-limit=256 my_file.o my_other_file.o LTO passes are run by a library instance invoked by the linker. Therefore any @@ -186,12 +189,5 @@ Adding Finer Granularity Once the pass in which an incorrect transformation is performed has been determined, it may be useful to perform further analysis in order to determine -which specific transformation is causing the problem. Ideally all passes -would be instrumented to allow skipping of individual transformations. This -functionality is available through the OptBisect object but it is impractical -to proactively instrument every existing pass. It is hoped that as developers -find that they need a pass to be instrumented they will add the instrumentation -and contribute it back to the LLVM source base. - -Helper functions will be added to simplify this level of instrumentation, but -this work is not yet completed. For more information, contact Andy Kaylor. +which specific transformation is causing the problem. Debug counters +can be used for this purpose. |