Add a specialized version of `shallow_resolve()`.

The super-hot call site of `inlined_shallow_resolve()` basically does
`r.inlined_shallow_resolve(ty) != ty`. This commit introduces a
version of that function specialized for that particular call pattern,
`shallow_resolve_changed()`. Incredibly, this reduces the instruction
count for `keccak` by 5%.

The commit also renames `inlined_shallow_resolve()` as
`shallow_resolve()` and removes the `inline(always)` annotation, as it's
no longer nearly so hot.

1 files changed, 1 insertions, 3 deletions

diff --git a/src/librustc/traits/fulfill.rs b/src/librustc/traits/fulfill.rs
index 5eaaeca82f2..805727b6ce0 100644
--- a/src/librustc/traits/fulfill.rs
+++ b/src/librustc/traits/fulfill.rs
@@ -264,9 +264,7 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
             // This `for` loop was once a call to `all()`, but this lower-level
             // form was a perf win. See #64545 for details.
             for &ty in &pending_obligation.stalled_on {
-                // Use the force-inlined variant of shallow_resolve() because this code is hot.
-                let resolved = ShallowResolver::new(self.selcx.infcx()).inlined_shallow_resolve(ty);
-                if resolved != ty {
+                if ShallowResolver::new(self.selcx.infcx()).shallow_resolve_changed(ty) {
                     changed = true;
                     break;
                 }