Alex Crichton de2a4601ab rustc: Use LLVM's new saturating float-to-int intrinsics ... This commit updates rustc, with an applicable LLVM version, to use LLVM's new `llvm.fpto{u,s}i.sat.*.*` intrinsics to implement saturating floating-point-to-int conversions. This results in a little bit tighter codegen for x86/x86_64, but the main purpose of this is to prepare for upcoming changes to the WebAssembly backend in LLVM where wasm's saturating float-to-int instructions will now be implemented with these intrinsics. This change allows simplifying a good deal of surrounding code, namely removing a lot of wasm-specific behavior. WebAssembly no longer has any special-casing of saturating arithmetic instructions and the need for `fptoint_may_trap` is gone and all handling code for that is now removed. This means that the only wasm-specific logic is in the `fpto{s,u}i` instructions which only get used for "out of bounds is undefined behavior". This does mean that for the WebAssembly target specifically the Rust compiler will no longer be 100% compatible with pre-LLVM 12 versions, but it seems like that's unlikely to be relied on by too many folks. Note that this change does immediately regress the codegen of saturating float-to-int casts on WebAssembly due to the specialization of the LLVM intrinsic not being present in our LLVM fork just yet. I'll be following up with an LLVM update to pull in those patches, but affects a few other SIMD things in flight for WebAssembly so I wanted to separate this change. Eventually the entire `cast_float_to_int` function can be removed when LLVM 12 is the minimum version, but that will require sinking the complexity of it into other backends such as Cranelfit.		2021-04-21 07:15:53 -07:00
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src	rustc: Use LLVM's new saturating float-to-int intrinsics	2021-04-21 07:15:53 -07:00
Cargo.toml	Add support for SHA256 source file hashing for LLVM 11+.	2020-10-14 15:09:51 -07:00