91d799eab0
Now that LLVM has been updated, the only remaining roadblock to implementing unwinding for MSVC is to fill out the runtime support in `std::rt::unwind::seh`. This commit does precisely that, fixing up some other bits and pieces along the way: * The `seh` unwinding module now uses `RaiseException` to initiate a panic. * The `rust_try.ll` file was rewritten for MSVC (as it's quite different) and is located at `rust_try_msvc_64.ll`, only included on MSVC builds for now. * The personality function for all landing pads generated by LLVM is hard-wired to `__C_specific_handler` instead of the standard `rust_eh_personality` lang item. This is required to get LLVM to emit SEH unwinding information instead of DWARF unwinding information. This also means that on MSVC the `rust_eh_personality` function is entirely unused (but is defined as it's a lang item). More details about how panicking works on SEH can be found in the `rust_try_msvc_64.ll` or `seh.rs` files, but I'm always open to adding more comments! A key aspect of this PR is missing, however, which is that **unwinding is still turned off by default for MSVC**. There is a [bug in llvm][llvm-bug] which causes optimizations to inline enough landing pads that LLVM chokes. If the compiler is optimized at `-O1` (where inlining isn't enabled) then it can bootstrap with unwinding enabled, but when optimized at `-O2` (inlining is enabled) then it hits a fatal LLVM error. [llvm-bug]: https://llvm.org/bugs/show_bug.cgi?id=23884 |
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| cfg | ||
| clean.mk | ||
| crates.mk | ||
| ctags.mk | ||
| debuggers.mk | ||
| dist.mk | ||
| docs.mk | ||
| grammar.mk | ||
| host.mk | ||
| install.mk | ||
| llvm.mk | ||
| main.mk | ||
| perf.mk | ||
| platform.mk | ||
| prepare.mk | ||
| reconfig.mk | ||
| rt.mk | ||
| rustllvm.mk | ||
| snap.mk | ||
| stage0.mk | ||
| target.mk | ||
| tests.mk | ||
| util.mk | ||