miri: we can use apfloat's mul_add now

[RalfJung]

With rust-lang/rustc_apfloat#11 fixed, there is no reason to still use host floats here.
Fixes rust-lang/miri#2995

We already have a test for this:

rust/src/tools/miri/tests/pass/float.rs

Lines 998 to 1003 in a7153db

	let f = f32::mul_add(
	-0.000000000000000000000000000000000000014728589,
	0.0000037105144,
	0.000000000000000000000000000000000000000000055,
	);
	assert_eq!(f.to_bits(), f32::to_bits(-0.0));

r? @oli-obk

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

The Miri subtree was changed

cc @rust-lang/miri

[oli-obk]

@bors r+ rollup

[bors]

📌 Commit f5d24e9 has been approved by oli-obk

It is now in the queue for this repository.

[workingjubilee]

diagnosing #142442

@rust-timer build ec9d3e5

[RalfJung]

I though the perf bot does the rollup splitting automatically?

[rust-timer]

Finished benchmarking commit (ec9d3e5): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

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

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (secondary 3.3%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -3.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.0%	[-3.5%, -2.6%]	2
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 754.993s -> 691.04s (-8.47%)
Artifact size: 372.27 MiB -> 372.22 MiB (-0.01%)

[workingjubilee]

@RalfJung It does, I was building a prebuilt in this thread for organizational reasons, since it's what Kobzol did.

[saethlin]

I though the perf bot does the rollup splitting automatically?

The perf bot builds a toolchain, it doesn't benchmark them. The "build" command that Jubilee used is how you benchmark a specific commit that already has a toolchain built 🙃