Strict provenance unwind

[niluxv]

1. Turned many usizes in the personality/unwind code that are actually pointers into *const u8.
2. Rewrote read_encoded_pointer to conform to strict-provenance, along the lines as described by @eddyb in zulip some time ago.

This should make supporting CHERI in the future easier (but they use a slightly modified format in the callsite table, which requires a CHERI specific modification to find_eh_action).

[rustbot]

r? @cuviper

(rustbot has picked a reviewer for you, use r? to override)

[jrtc27]

(but they use a slightly modified format in the callsite table, which requires a CHERI specific modification to find_eh_action)

FWIW I don't think we believe that's what should be specified in a real standard. It's a bit of a hack cooked up to make things work that's stuck around.

[cuviper]

I confess I don't know all the depths of unwinding, but functionally this change looks good to me...

@bors r+

[bors]

📌 Commit a10751f has been approved by cuviper

It is now in the queue for this repository.

[fmease]

Failed in rollup.
@bors r-

[niluxv]

Oops, forgot to check other targets. Is there a simple way to do x check library for a non-host target?

Anyway, the problem should be fixed now. (And rebased.)

[workingjubilee]

Iiiii think you can pass --target?

This checks out to me, also.
@bors r=cuviper,workingjubilee

[bors]

📌 Commit cb3d5ce has been approved by cuviper,workingjubilee

It is now in the queue for this repository.

[workingjubilee]

@bors rollup=iffy

[bors]

⌛ Testing commit cb3d5ce with merge 66efacf...

[bors]

💔 Test failed - checks-actions

[workingjubilee]

whoops, the "GitHub code review focuses on diffs, not necessarily places which pattern-match the diff" problem strikes again.

[niluxv]

I'm sorry for consuming so many Bors runs.

Rebased and hopefully fixed all remaining issues.

Iiiii think you can pass --target?

Hm, yes, but that requires a C cross-compilation toolchain for that target. I installed one for arm-unknown-linux-gnueabi now, so I could check for that target.

[workingjubilee]

oh, hon...

you're not even in the double digits.

[cuviper]

@bors r=cuviper,workingjubilee

[bors]

📌 Commit b48039f has been approved by cuviper,workingjubilee

It is now in the queue for this repository.

[bors]

⌛ Testing commit b48039f with merge 6b382eb...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

The job aarch64-gnu failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] rustc_error_messages test:false 5.074
   Compiling tracing-tree v0.2.4
[RUSTC-TIMING] tracing_tree test:false 0.938
   Compiling rustc_log v0.0.0 (/checkout/compiler/rustc_log)
##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
##[group]Clock drift check
##[group]Clock drift check
Session terminated, killing shell...[RUSTC-TIMING] regex test:false 19.477
  network time: Thu, 19 Oct 2023 00:01:50 GMT
##[endgroup]
[RUSTC-TIMING] object test:false 12.403
[RUSTC-TIMING] serde_json test:false 4.583

[cuviper]

@bors retry

[bors]

⌛ Testing commit b48039f with merge 020d008...

[bors]

☀️ Test successful - checks-actions
Approved by: cuviper,workingjubilee
Pushing 020d008 to master...

[rust-timer]

Finished benchmarking commit (020d008): 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)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.4%	[-1.4%, -1.4%]	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)	-	-	0
Regressions ❌ (secondary)	3.7%	[3.1%, 4.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

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: 628.777s -> 628.239s (-0.09%)
Artifact size: 304.01 MiB -> 303.97 MiB (-0.01%)