Align unsized locals

[tmiasko]

Allocate an extra space for unsized locals and manually align the storage, since alloca doesn't support dynamic alignment.

Fixes #71416.
Fixes #71695.

[rustbot]

r? @cjgillot

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[cjgillot]

@bors r+

[bors]

📌 Commit 83a5a69 has been approved by cjgillot

It is now in the queue for this repository.

[bors]

⌛ Testing commit 83a5a69 with merge 2c41369...

[bors]

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 2c41369 to master...

[rust-timer]

Finished benchmarking commit (2c41369): 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)	-0.4%	[-0.4%, -0.4%]	2
Improvements ✅ (secondary)	-0.5%	[-0.7%, -0.3%]	5
All ❌✅ (primary)	-0.4%	[-0.4%, -0.4%]	2

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)	2.4%	[2.4%, 2.4%]	1
Improvements ✅ (primary)	-1.3%	[-1.3%, -1.3%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.3%	[-1.3%, -1.3%]	1

Cycles

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

Binary size

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

Bootstrap: 659.669s -> 659.849s (0.03%)