rust/tests/ui/lto/lto-many-codegen-units.rs

//@ run-pass
//@ compile-flags: -C lto -C codegen-units=8
//@ no-prefer-dynamic

fn main() {
}
tests: Add missing run-pass annotations 2019-07-26 21:54:25 +00:00			`//@ run-pass`
rustc: Enable LTO and multiple codegen units This commit is a refactoring of the LTO backend in Rust to support compilations with multiple codegen units. The immediate result of this PR is to remove the artificial error emitted by rustc about `-C lto -C codegen-units-8`, but longer term this is intended to lay the groundwork for LTO with incremental compilation and ultimately be the underpinning of ThinLTO support. The problem here that needed solving is that when rustc is producing multiple codegen units in one compilation LTO needs to merge them all together. Previously only upstream dependencies were merged and it was inherently relied on that there was only one local codegen unit. Supporting this involved refactoring the optimization backend architecture for rustc, namely splitting the `optimize_and_codegen` function into `optimize` and `codegen`. After an LLVM module has been optimized it may be blocked and queued up for LTO, and only after LTO are modules code generated. Non-LTO compilations should look the same as they do today backend-wise, we'll spin up a thread for each codegen unit and optimize/codegen in that thread. LTO compilations will, however, send the LLVM module back to the coordinator thread once optimizations have finished. When all LLVM modules have finished optimizing the coordinator will invoke the LTO backend, producing a further list of LLVM modules. Currently this is always a list of one LLVM module. The coordinator then spawns further work to run LTO and code generation passes over each module. In the course of this refactoring a number of other pieces were refactored: * Management of the bytecode encoding in rlibs was centralized into one module instead of being scattered across LTO and linking. * Some internal refactorings on the link stage of the compiler was done to work directly from `CompiledModule` structures instead of lists of paths. * The trans time-graph output was tweaked a little to include a name on each bar and inflate the size of the bars a little 2017-07-23 15:14:38 +00:00			`//@ compile-flags: -C lto -C codegen-units=8`
			`//@ no-prefer-dynamic`

			`fn main() {`
			`}`