Enable -disable-i2p-p2i-opt flag

[nikic]

For perf test.

r? @ghost

[nikic]

@bors try @rust-timer queue

[nikic]

I think the cause of the ptrtoint/inttoptr casts in this case is SROA on something like this: https://llvm.godbolt.org/z/576Gb1fEx

Ideally this would not produce any casts (there are uses with different types, but those uses are disjoint), but if it does it's probably better to chose ptr as the common type, as ptrtoint(inttoptr) can be elided, unlike the reverse.

[saethlin]

as ptrtoint(inttoptr) can be elided, unlike the reverse.

Are you sure that can be elided? It has the side effect of exposing the original address. I feel like you'd need to also prove that nobody knows about that address, which seems impossible?

[nikic]

ptrtoint will expose the provenance of the pointer returned by inttoptr. However, inttoptr can only return a previously exposed provenance. As such, ptrtoint is exposing a previously exposed provenance, and the second expose can be elided.

[rust-bors]

☀️ Try build successful (CI)
Build commit: cc94b4f (cc94b4f9704e819353d2cc91d0b7cc1a7e767016, parent: 94ecb52bbeeccc990545d4ebc9e9c35dcaf285e3)

[rust-timer]

Finished benchmarking commit (cc94b4f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.1%, 0.4%]	31
Regressions ❌ (secondary)	0.4%	[0.1%, 2.0%]	64
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	3
All ❌✅ (primary)	0.1%	[-2.9%, 0.4%]	32

Max RSS (memory usage)

Results (primary -1.3%)

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)	-	-	0
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

Results (primary -0.2%, secondary -0.0%)

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

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-1.1%, -0.0%]	5
Improvements ✅ (secondary)	-0.0%	[-0.1%, -0.0%]	36
All ❌✅ (primary)	-0.2%	[-1.1%, 0.0%]	8

Bootstrap: 470.352s -> 470.75s (0.08%)
Artifact size: 387.80 MiB -> 387.85 MiB (0.01%)