This PR both adds in-source documentation on what to look out for
when adding a new (X86) feature set and adds all that are detectable at run-time in Rust stable
as of 1.27.0.
This should only enable the use of the corresponding LLVM intrinsics.
Actual intrinsics need to be added separately in rust-lang/stdarch.
It also re-orders the run-time-detect test statements to be more consistent
with the actual list of intrinsics whitelisted and removes underscores not present
in the actual names (which might be mistaken as being part of the name)
Preparation for a subsequent change that replaces
rustc_target::config::Config with its wrapped Target.
On its own, this commit breaks the build. I don't like making
build-breaking commits, but in this instance I believe that it
makes review easier, as the "real" changes of this PR can be
seen much more easily.
Result of running:
find compiler/ -type f -exec sed -i -e 's/target\.target\([)\.,; ]\)/target\1/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target\.target$/target/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target.ptr_width/target.pointer_width/g' {} \;
./x.py fmt
These target features have to be supported or at least emulated by
alternative codegen backends anyway as they are used by common crates.
By moving this list to cg_ssa, other codegen backends don't have to copy
this code.
