At opt-level=0, don't apply !nonnull or !range metadata to loads

[erikdesjardins]

This metadata is only used for optimization, so it shouldn't have any significant effect with the minimal LLVM pipeline at opt-level=0.

This may provide a small perf improvement for debug builds. (needs a perf run to confirm)

[rust-highfive]

r? @petrochenkov

(rust-highfive has picked a reviewer for you, use r? to override)

[erikdesjardins]

r? @tmiasko

[nikic]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit 03cc0cd with merge c0e91490a61b2cb72813bb297ed88232ed1d3e57...

[bors]

☀️ Try build successful - checks-actions
Build commit: c0e91490a61b2cb72813bb297ed88232ed1d3e57 (c0e91490a61b2cb72813bb297ed88232ed1d3e57)

[rust-timer]

Queued c0e91490a61b2cb72813bb297ed88232ed1d3e57 with parent f838a42, future comparison URL.

[rust-timer]

Finished benchmarking commit (c0e91490a61b2cb72813bb297ed88232ed1d3e57): comparison url.

Summary: This benchmark run did not return any relevant results. 3 results were found to be statistically significant but too small to be relevant.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression

[erikdesjardins]

Huh, I would've thought adding metadata was more expensive than adding enum attributes, but either it isn't or we don't apply these attributes to very many loads.