Remove ArrayEncoding usage from Digest and delete ArrayEncoding.

[briansmith]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1598583) 96.00% compared to head (149904c) 95.99%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1731      +/-   ##
==========================================
- Coverage   96.00%   95.99%   -0.02%     
==========================================
  Files         137      137              
  Lines       20749    20753       +4     
  Branches      226      226              
==========================================
+ Hits        19920    19921       +1     
- Misses        795      798       +3     
  Partials       34       34              

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[briansmith]

I still need to benchmark this. Will add benchmarks for ring::digest in another PR.

[briansmith]

@joshlf This removes the last unsafe from ring::endian.

[joshlf]

Nice!

[briansmith]

This has been blocked on adding (back) the benchmarks for ring::digest to ensure this doesn't negatively affect performance. Those are in #1809 now.

[briansmith]

Using the benchmark added in PR #1809, I found that my original implementation here did have a notable performance regression. To fix it, I had to make this change:

     let mut output = Output([0; MAX_OUTPUT_LEN]);
     output
         .0
-        .iter_mut()
-        .zip(input.iter().copied().flat_map(|Wrapping(w)| f(w)))
+        .chunks_mut(N)
+        .zip(input.iter().copied().map(|Wrapping(w)| f(w)))
         .for_each(|(o, i)| {
-            *o = i;
+            o.copy_from_slice(&i);
         });
     output
 }

I verified that this generates the same assembly code as the original code on x86-64 using Rust 1.74.0, except that there are two additional 128-bit moves in sha256_formta_output to zero out the latter half of Output, which was intended.

[briansmith]

The codecov "project" coverage % "failure" is expected since this reduces the amount of covered code.