This commit removes the `-D warnings` flag being passed through the makefiles to
all crates to instead be a crate attribute. We want these attributes always
applied for all our standard builds, and this is more amenable to Cargo-based
builds as well.
Note that all `deny(warnings)` attributes are gated with a `cfg(stage0)`
attribute currently to match the same semantics we have today
When the inliner has to decided if it wants to inline a function A into an
internal function B, it first checks whether it would be more profitable
to inline B into its callees instead. This means that it has to analyze
B, which involves checking the assumption cache. Building the assumption
cache requires scanning the whole function, and because inlining
currently clears the assumption cache, this scan happens again and
again, getting even slower as the function grows from inlining.
As inlining the huge find functions isn't really useful anyway, we can
mark them as noinline, which skips the cost analysis and reduces compile
times by as much as 70%.
cc #28273
I believe everything that doesn't take a constant integer up to SSE4.2
should now be correct (I don't have any reason to believe that those
that do take constant integers are wrong; they're just more complicated
and I just haven't tested them in detail).
This adds support for flattened intrinsics, which are called in Rust
with tuples but in LLVM without them (e.g. `foo((a, b))` becomes `foo(a,
b)`). Unflattened ones could be supported, but are not yet.
This is necessary to reflect the ARM APIs accurately, since some
functions explicitly take an unsigned parameter and a signed one, of the
same integer shape, so the no-duplicates check will fail unless we
distinguish.
