Get rid of EscapeDebugInner.

[reitermarkus]

I read the note on EscapeDebugInner and thought I'd give it a try.

[rustbot]

r? @thomcc

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[hkBst]

-        // SAFETY: `self.data.escape_seq` contains an escape sequence, as is 
-        // guaranteed by the caller, and in that case `self.alive` is guaranteed 
+        // SAFETY: `self.data.escape_seq` contains an escape sequence, as is
+        // guaranteed by the caller, and in that case `self.alive` is guaranteed

I'm sure you know this, but if you highlight these lines, you can see that the trailing space is the problem.

[hkBst]

@thomcc I think it would make sense to see the perf impact of this change, since it is supposed to be an optimization (and increases the use of unsafe). Otherwise it seems hard to determine if this is a worthy trade-off.

[reitermarkus]

r? libs

[rustbot]

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[tgross35]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 8b1d999 with merge 174fdb8...

[bors]

☀️ Try build successful - checks-actions
Build commit: 174fdb8 (174fdb8cd5ea329d04af0f4ab8064f1c849bda29)

[rust-timer]

Finished benchmarking commit (174fdb8): comparison URL.

Overall result: no relevant changes - 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 benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (primary -0.4%, secondary 2.8%)

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)	1.8%	[0.6%, 3.9%]	3
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-1.8%	[-4.1%, -0.4%]	5
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.4%	[-4.1%, 3.9%]	8

Cycles

Results (primary -0.5%, secondary 1.5%)

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)	2.5%	[2.2%, 2.7%]	4
Improvements ✅ (primary)	-0.5%	[-0.6%, -0.5%]	2
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-0.5%	[-0.6%, -0.5%]	2

Binary size

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

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)	-	-	0
Improvements ✅ (primary)	-0.0%	[-0.0%, -0.0%]	4
Improvements ✅ (secondary)	-0.0%	[-0.1%, -0.0%]	35
All ❌✅ (primary)	-0.0%	[-0.0%, -0.0%]	4

Bootstrap: 762.088s -> 762.832s (0.10%)
Artifact size: 365.14 MiB -> 365.11 MiB (-0.01%)

[tgross35]

Sorry for the delay, this looks reasonably good to me but I want to be sure I understand the design first.

[tgross35]

What is the value of this being a union? Assuming N >= 4, it seems like any chars could just be written to escape_seq to eliminate the union unsafety.

[reitermarkus]

ascii::Char only ranges from 0 to 127. So you would have to store both in [u8; N] instead, and transmute both variants.

[tgross35]

@rustbot author