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I am trying to add my llvm pass into Rustc. Rustc has one compiling option -C passes=val where we could add extra LLVM passes to run. However, as my try, this option can only accept the pass when the pass code is placed inside the LLVM code tree, but I want to add my pass out-of-tree into Rustc.

When I add my pass via this option:
RUSTFLAGS="-C passes=my-pass" cargo build
Compiler reports errors:
error: failed to run LLVM passes: unknown pass name 'my-pass'

Then I try to load my pass via -C llvm-args=-fpass-plugin=/opt/new-pass/mypass.so -C passes=my-pass in the clang way. It reports: rustc -Cllvm-args="..." with: Unknown command line argument '-fpass-plugin=/opt/new-pass/mypass.so'. Also tried to replace -fpass-plugin with other options like -load and -load-pass-plugin, but they still cannot be recognized by rustc.

How could I add my custom pass into Rustc?

Jerry
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1 Answers1

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I was trying to find a solution to this exact problem too. According to a rust developer on their Zulip Chat, it looks like you need to build a custom rustc with plugin support.

Derrick McKee
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