Default to sha256 for hashing source files

[saethlin]

r? @ghost

[saethlin]

@bors try @rust-timer queue

[bors]

⌛ Trying commit b576384 with merge e41bdac...

[bors]

☀️ Try build successful - checks-actions
Build commit: e41bdac (e41bdac566c5933abbe556cea1b75d7b6793340c)

[joshtriplett]

Would it be worth testing blake3 as well, to see if it helps with performance?

[rust-timer]

Finished benchmarking commit (e41bdac): comparison URL.

Overall result: ✅ improvements - no 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.

@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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.5%, -0.3%]	14
Improvements ✅ (secondary)	-0.8%	[-2.2%, -0.2%]	20
All ❌✅ (primary)	-0.4%	[-0.5%, -0.3%]	14

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)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	2.5%	[2.5%, 2.5%]	1
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.9%	[-2.7%, 0.9%]	2

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: 634.138s -> 631.491s (-0.42%)
Artifact size: 317.56 MiB -> 317.55 MiB (-0.00%)

[Kobzol]

I tested blake3 a few months ago. There were small-ish perf. wins, but it didn't seem worth it in the grand scheme of things to introduce a new dependency. But I haven't run the whole perf. suite on it, just a few local experiments.

[ChrisDenton]

I would ask why this was previously msvc only? If there was a reason for excluding other platforms then it'd be good to know if those reasons have been solved or if they're still outstanding.

[klensy]

#113707
#113707 (comment)

[saethlin]

If this can be landed, it would need a lot of other improvements outside of rustc itself first. Maybe I'll poke DWARF about this; if MD5 isn't good enough for Microsoft I don't see why it should be good enough for DWARF.