5ec56e5fbb
Pick the max DWARF version when LTO'ing modules with different versions Currently, when rustc compiles code with `-Clto` enabled that was built with different choices for `-Zdwarf-version`, a warning will be reported. It's very easy to observe this by compiling most anything (eg, "hello world") and specifying `-Clto -Zdwarf-version=5` since the standard library is distributed with `-Zdwarf-version=4`. This behavior isn't actually useful for a few reasons: - From observation, LLVM chooses to pick the highest DWARF version anyway after issuing the warning. - Clang specifies that in this case, the max version should be picked without a warning and as a general principle, we want to support x-lang LTO with Clang which implies using the same module flag merge behaviors. - Debuggers need to be able to handle a variety of versions within the same debugging session as you can easily have some parts of a binary (or some dynamic libraries within an application) all compiled with different DWARF versions. This commit changes the module flag merge behavior to match Clang and use the highest version of DWARF. It also adds a test to ensure this behavior is respected in the case of two crates being LTO'd together and adds a test to ensure no warning is printed. Fixes #130041 which fails due to these warnings being printed cc #103057 |
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| messages.ftl | ||
| README.md | ||
The codegen crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.