Revert "Apply EarlyOtherwiseBranch to scalar value #129047"

[jieyouxu]

This reverts PR #129047, commit a772336, reversing changes made to 702987f.

cc @dianqk and @cjgillot as the PR author and reviewer of #129047 respectively.

It seems Apply EarlyOtherwiseBranch to scalar value #129047 may have lead to several nightly regressions:

• Panic while compiling http-body v0.4.6 with rustc 1.83.0-nightly (7042c269c 2024-09-23) #130769
• panic in nightly compiler installing mdbook #130774
• Compiler panik #130771

Example test that would ICE with changes in #129047 (this test is included in this PR):

//@ compile-flags: -C opt-level=3
//@ check-pass

use std::task::Poll;

pub fn poll(val: Poll<Result<Option<Vec<u8>>, u8>>) {
    match val {
        Poll::Ready(Ok(Some(_trailers))) => {}
        Poll::Ready(Err(_err)) => {}
        Poll::Ready(Ok(None)) => {}
        Poll::Pending => {}
    }
}

Since this is a mir-opt ICE that seems to quite easy to trigger with real-world crates being affected, let's revert for now and reland the mir-opt after these are fixed.

[rustbot]

r? @chenyukang

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[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[chenyukang]

r? @rust-lang/wg-mir-opt

[fmease]

Could you perhaps add a regression test (in a separate commit)?

[jieyouxu]

Could you perhaps add a regression test (in a separate commit)?

(I did just before you asked lol)

[nagisa]

@bors r+ p=1

Fixing a critical regression, should land ASAP.

[bors]

📌 Commit ad7eb48 has been approved by nagisa

It is now in the queue for this repository.

[bors]

⌛ Testing commit ad7eb48 with merge 3b262d8...

[rust-log-analyzer]

The job x86_64-gnu-aux failed! Check out the build log: (web) (plain)

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

warning: spurious network error (1 tries remaining): [28] Timeout was reached (Operation too slow. Less than 10 bytes/sec transferred the last 30 seconds)
warning: spurious network error (1 tries remaining): [28] Timeout was reached (Operation too slow. Less than 10 bytes/sec transferred the last 30 seconds)
warning: spurious network error (1 tries remaining): [28] Timeout was reached (Operation too slow. Less than 10 bytes/sec transferred the last 30 seconds)
warning: spurious network error (1 tries remaining): [28] Timeout was reached (Operation too slow. Less than 10 bytes/sec transferred the last 30 seconds)
error: failed to get `half` as a dependency of package `ciborium-ll v0.2.2`
    ... which satisfies dependency `ciborium-ll = "^0.2.2"` (locked to 0.2.2) of package `ciborium v0.2.2`
    ... which satisfies dependency `ciborium = "^0.2.0"` (locked to 0.2.2) of package `criterion v0.5.1`
    ... which satisfies dependency `criterion = "^0.5.1"` (locked to 0.5.1) of package `benchsuite v0.0.0 (/checkout/src/tools/cargo/benches/benchsuite)`
Caused by:
Caused by:
  download of ha/lf/half failed
Caused by:
Caused by:
  failed to download from `https://index.crates.io/ha/lf/half`
Caused by:
  [28] Timeout was reached (Operation too slow. Less than 10 bytes/sec transferred the last 30 seconds)
Build completed unsuccessfully in 0:26:32
Build completed unsuccessfully in 0:26:32
make: *** [Makefile:51: check-aux] Error 1
  network time: Tue, 24 Sep 2024 12:01:13 GMT
##[error]Process completed with exit code 2.
Post job cleanup.

[bors]

💔 Test failed - checks-actions

[jieyouxu]

@bors retry (spurious network error)

[bors]

⌛ Testing commit ad7eb48 with merge 67bb749...

[bors]

☀️ Test successful - checks-actions
Approved by: nagisa
Pushing 67bb749 to master...

[rust-timer]

Finished benchmarking commit (67bb749): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-1.1%, 0.6%]	2

Max RSS (memory usage)

Results (primary -4.0%, secondary 3.7%)

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%	[3.6%, 3.8%]	2
Improvements ✅ (primary)	-4.0%	[-6.6%, -1.5%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-4.0%	[-6.6%, -1.5%]	2

Cycles

Results (primary -0.6%)

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)	0.6%	[0.5%, 0.7%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.9%	[-2.1%, -1.7%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.6%	[-2.1%, 0.7%]	4

Binary size

Results (primary -0.4%, 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)	0.1%	[0.1%, 0.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.5%	[-0.8%, -0.1%]	3
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-0.4%	[-0.8%, 0.1%]	4

Bootstrap: 769.56s -> 767.328s (-0.29%)
Artifact size: 340.89 MiB -> 340.88 MiB (-0.00%)

[lqd]

This is a revert, no investigation needed.

@rustbot label: +perf-regression-triaged