compiler/main/DriverPipeline.hs¶
Note [-Xlinker -rpath vs -Wl,-rpath]¶
-Wl takes a comma-separated list of options which in the case of -Wl,-rpath -Wl,some,path,with,commas parses the path with commas as separate options. Buck, the build system, produces paths with commas in them.
-Xlinker doesn’t have this disadvantage and as far as I can tell it is supported by both gcc and clang. Anecdotally nvcc supports -Xlinker, but not -Wl.
Note [Produce big objects on Windows]¶
The Windows Portable Executable object format has a limit of 32k sections, which we tend to blow through pretty easily. Thankfully, there is a “big object” extension, which raises this limit to 2^32. However, it must be explicitly enabled in the toolchain:
- the assembler accepts the -mbig-obj flag, which causes it to produce a bigobj-enabled COFF object.
- the linker accepts the –oformat pe-bigobj-x86-64 flag. Despite what the name suggests, this tells the linker to produce a bigobj-enabled COFF object, no a PE executable.
We must enable bigobj output in a few places:
- When merging object files (DriverPipeline.joinObjectFiles)
- When assembling (DriverPipeline.runPhase (RealPhase As …))
Unfortunately the big object format is not supported on 32-bit targets so none of this can be used in that case.
