Steal MIR for CTFE when possible.

[cjgillot]

Some bodies, like constants, have CTFE MIR but no optimized MIR.
In that case, have mir_for_ctfe steal the MIR instead of cloning it.

[cjgillot]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 3e01572c4e541200d43f848893f591714bfa3656 with merge b8b2be5074b7b3846f46bb9c363baa66d7685448...

[bors]

☀️ Try build successful - checks-actions
Build commit: b8b2be5074b7b3846f46bb9c363baa66d7685448 (b8b2be5074b7b3846f46bb9c363baa66d7685448)

[rust-timer]

Finished benchmarking commit (b8b2be5074b7b3846f46bb9c363baa66d7685448): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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 may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.3%	[0.8%, 1.4%]	7
Regressions ❌ (secondary)	0.8%	[0.5%, 1.0%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.4%	[-2.6%, -0.6%]	19
All ❌✅ (primary)	1.3%	[0.8%, 1.4%]	7

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.7%	[2.7%, 2.7%]	1
Improvements ✅ (primary)	-1.1%	[-1.4%, -0.8%]	2
Improvements ✅ (secondary)	-2.6%	[-4.3%, -1.2%]	10
All ❌✅ (primary)	-1.1%	[-1.4%, -0.8%]	2

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-11.6%	[-12.5%, -11.0%]	6
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 650.338s -> 649.841s (-0.08%)

[cjgillot]

instr-count is balanced, while cycle count and max-rss appear greener.
r? compiler

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[lqd]

and the incremental compilation benchmarks have been quite noisy on bitmaps yesterday/today

[oli-obk]

r? @oli-obk

@bors r+

[bors]

📌 Commit 02e10a0 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 02e10a0 with merge f362387...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing f362387 to master...

[rust-timer]

Finished benchmarking commit (f362387): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	1
Improvements ✅ (secondary)	-1.5%	[-2.6%, -0.5%]	19
All ❌✅ (primary)	-0.6%	[-0.6%, -0.6%]	1

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	1.4%	[1.4%, 1.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.7%	[-4.3%, -1.9%]	7
All ❌✅ (primary)	1.3%	[1.3%, 1.3%]	1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.8%	[4.8%, 6.7%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-2.4%, -2.0%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 651.433s -> 650.04s (-0.21%)