Re-enable ThinLTO for rustc on x86_64-apple-darwin

[lqd]

ThinLTO was disabled on x64 mac in #105646 because of the #105637 regression.

It was later discovered that the issue was present on other targets as well, as the mac revert was already landing. The linux/win reverts, however, did not land before the root cause was identified.

#105800 fixed the underlying issue in -Zdylib-lto handling, and the x64 msvc and linux targets are now fixed, ICEs are using the correct rustc_driver panic hook.

This PR re-enables ThinLTO on mac for improved perf now that the issue should be fixed everywhere.

[lqd]

@bors try

[bors]

⌛ Trying commit a270a348bc99a57e25b39e58db466f928f03439b with merge 16aba2156f3ed344308e345c000744d0476fd9ec...

[Mark-Simulacrum]

r=me on the re-enable presuming try builds look good

[bors]

☀️ Try build successful - checks-actions
Build commit: 16aba2156f3ed344308e345c000744d0476fd9ec (16aba2156f3ed344308e345c000744d0476fd9ec)

[lqd]

This is looking good, the 16aba2156f3ed344308e345c000744d0476fd9ec build correctly displays the ICE from #105777 like nightly does. It does not print correctly with the ThinLTOed nightly-2012-12-12 where the issue was found.

I've dropped the temporary CI builder hack.

For bisection and perf we can avoid rolling it up, but it shouldn't really matter.

@bors r=Mark-Simulacrum rollup=never

[bors]

📌 Commit ae68e17 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit ae68e17 with merge f6f6328ec504cb9ab8ef1234282ff206d65f3657...

[bors]

💥 Test timed out

[lqd]

@bors retry - x86_64-gnu-llvm-13-stage1 was unresponsive while compiling rustbuild right at the beginning

[bors]

⌛ Testing commit ae68e17 with merge 1072337...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 1072337 to master...

[rust-timer]

Finished benchmarking commit (1072337): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

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)	5.6%	[5.6%, 5.6%]	1
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-2.1%	[-4.2%, -0.6%]	21
All ❌✅ (primary)	-2.3%	[-2.3%, -2.3%]	1

Cycles

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