slices: optimize Compact and CompactFunc

[zigo101]

Try to save a comparison in the loop bodies of Compact and CompactFunc.

Note: due to #64272, some bound checks still fail to be removed.

                        │ old.txt  │             new.txt              │
                        │   sec/op    │   sec/op     vs base                │

Compact/nil-4 4.191n ± 9% 3.402n ± 1% -18.84% (p=0.000 n=10)
Compact/one-4 5.289n ± 2% 4.553n ± 2% -13.93% (p=0.000 n=10)
Compact/sorted-4 9.865n ± 0% 6.882n ± 1% -30.24% (p=0.000 n=10)
Compact/2_items-4 11.10n ± 2% 12.11n ± 2% +9.00% (p=0.000 n=10)
Compact/unsorted-4 9.831n ± 3% 6.918n ± 2% -29.62% (p=0.000 n=10)
Compact/many-4 16.40n ± 4% 14.90n ± 1% -9.20% (p=0.000 n=10)
Compact/dup_start-4 29.87n ± 0% 28.06n ± 3% -6.04% (p=0.001 n=10)
Compact_Large/all_dup-4 13.11µ ± 0% 13.12µ ± 0% ~ (p=0.971 n=10)
Compact_Large/no_dup-4 6.972µ ± 0% 5.806µ ± 0% -16.73% (p=0.000 n=10)
CompactFunc/nil-4 5.300n ± 0% 5.309n ± 1% ~ (p=0.289 n=10)
CompactFunc/one-4 6.051n ± 1% 6.442n ± 3% +6.46% (p=0.000 n=10)
CompactFunc/sorted-4 16.24n ± 1% 12.79n ± 2% -21.24% (p=0.000 n=10)
CompactFunc/2_items-4 17.89n ± 1% 17.75n ± 0% -0.75% (p=0.000 n=10)
CompactFunc/unsorted-4 16.26n ± 0% 12.83n ± 1% -21.07% (p=0.000 n=10)
CompactFunc/many-4 30.71n ± 1% 29.07n ± 0% -5.32% (p=0.000 n=10)
CompactFunc/dup_start-4 78.94n ± 1% 67.19n ± 1% -14.89% (p=0.000 n=10)
CompactFunc_Large/all_dup-4 3.277m ± 0% 3.692m ± 2% +12.67% (p=0.000 n=10)
CompactFunc_Large/no_dup-4 4.019m ± 0% 2.826m ± 1% -29.68% (p=0.000 n=10)
geomean 109.6n 96.99n -11.47%

[gopherbot]

This PR (HEAD: d642ac1) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/543661.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR (HEAD: a912a34) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/543661.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

This PR (HEAD: d2236ae) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/543661.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Xu Liu:

Patch Set 3:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR (HEAD: 5df3a7a) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/543661.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Xu Liu:

Patch Set 6:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR (HEAD: cea3d93) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/543661.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Keith Randall:

Patch Set 8: Auto-Submit+1 Code-Review+2 Commit-Queue+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 8:

Dry run: CV is trying the patch.

Bot data: {"action":"start","triggered_at":"2023-11-28T21:43:24Z","revision":"017dc099225d00d172b4e7017fe1a7fd45c1bd33"}

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Keith Randall:

Patch Set 8: Code-Review+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Keith Randall:

Patch Set 8: -Commit-Queue

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 8:

This CL has passed the run

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 8: LUCI-TryBot-Result+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 8:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Keith Randall:

Patch Set 8:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 8:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Xu Liu:

Patch Set 8:

(3 comments)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/543661.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR is being closed because golang.org/cl/543661 has been merged.