Compile libcore to llvm IR (bytecode)

libs
1

guys,

We are building a symbolic executor for Rust, but got trouble building standard library into llvm IR(bytecode), e.g., libcore.

we tried everything found by google:

  • rustc --emit=llvm-bc src/libcore/lib.rs
  • xbuild etc

nothing worked so far, any idea ? thanks!

2

What are the problems?

As a workaround you could take libcore-.rlib from somewere in the sysroot (rustc --print sysroot) and use ar x to extract it. One of the files has bc as an extension. I believe it is compressed with flate2, so you will have to decompress it. This is an implementation detail, so it can change at any moment.

3

What exactly are you getting as an error? rustc --emit=llvm-ir kind of works for me (e.g. it is what cargo llvm-ir uses) and dumps llvm-ir, you could then compile that to bytecode manually.

4

below is the syntax error I got :

~/work/rust.git$ rustc --emit=llvm-bc src/libcore/lib.rs

error[E0642]: patterns aren't allowed in methods without bodies --> src/libcore/iter/traits/iterator.rs:1742:51 | 1742 | fn partition_in_place<'a, T: 'a, P>(mut self, ref mut predicate: P) -> usize | ^^^^^^^^^^^^^^^^^ | help: give this argument a name or use an underscore to ignore it | 1742 | fn partition_in_place<'a, T: 'a, P>(mut self, _: P) -> usize | ^

error[E0432]: unresolved import manually_drop --> src/libcore/mem/mod.rs:18:9 | 18 | pub use manually_drop::ManuallyDrop; | ^^^^^^^^^^^^^ help: a similar path exists: self::manually_drop

error[E0432]: unresolved import maybe_uninit --> src/libcore/mem/mod.rs:22:9 | 22 | pub use maybe_uninit::MaybeUninit; | ^^^^^^^^^^^^ help: a similar path exists: self::maybe_uninit

5

The latter two sounds like an edition import handling difference; make sure you compile the crates in the correct edition (I think all the stdlib crates are edition2018).

6

I am using top of rust.git tree with version info:

Merge: f8fd462 ae03e16 Author: bors bors@rust-lang.org Date: Fri Feb 7 06:24:55 2020 +0000

rustc is in-tree installed, with version info: rustc 1.43.0-dev

7

thanks bjorn3 for the reply.

once you ar x to extract the rlib file, the .bc.z file is not in flate2 format, it is flate2 with customized header, exact description is here: RUST_OBJECT format

the decompressing code is in same rs file.

I am not aware of any standalone utility to decode this format, but with link above, not hard to create one.

thanks

8

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