fix bit_count on arm

[daviszhen]

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue #25046

What this PR does / why we need it:

原因:

BIT_COUNT(negative DOUBLE) comment 是对的
我用最小程序复现了 /mnt/fastdata/temp2/matrixone/pkg/sql/plan/function/func_unary.go:605 的逻辑：

rounded := math.RoundToEven(val)
uint64(rounded)

结果：

amd64/go1.25.x：

-1.4 -> rounded=-1 -> uint64=0xffffffffffffffff -> bits=64
arm64/go1.25.4：

-1.4 -> rounded=-1 -> uint64=0 -> bits=0
所以 comment 里说的 ARM64 上“负浮点转 uint64 变成 0”我已经实测确认了。
这说明 bitCountFromFloat() 的实现确实有跨架构问题，不应该依赖这个转换行为。

修改方案: 先转in64, 再转uint64. 已经在arm64上验证了.

[qodo-code-review]

Qodo reviews are paused for this user.

Troubleshooting steps vary by plan Learn more →

On a Teams plan?
Reviews resume once this user has a paid seat and their Git account is linked in Qodo.
Link Git account →

Using GitHub Enterprise Server, GitLab Self-Managed, or Bitbucket Data Center?
These require an Enterprise plan - Contact us
Contact us →

[XuPeng-SH]

Re-checked the current head. The fix is narrowly scoped and correct for the actual cross-arch bug: negative FLOAT/DOUBLE values are now rounded first and then converted through int64 before the uint64 bit-count path, which avoids the ARM-specific zeroing behavior while preserving the existing MinInt64 clamp. The added regression cases hit the exact problematic boundary values, and I do not see a remaining correctness issue to block on.

[mergify]

Queued — the merge queue status continues in this comment ↓.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-06-22 12:46 UTC · Rule: main · triggered by rule Automatic queue on approval for main
• ✅ Checks passed · in-place
• ✅ Merged — 2026-06-22 14:00 UTC · at 03cd594ec6cc53574c35f4b4ceb6ce137f00cb2a · squash

This pull request spent 1 hour 14 minutes 20 seconds in the queue, including 1 hour 13 minutes 54 seconds running CI.

Required conditions to merge

• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • fix bit_count on arm #25076
• #review-threads-unresolved = 0 [🛡 GitHub branch protection]
  • fix bit_count on arm #25076
• github-review-decision = APPROVED [🛡 GitHub branch protection]
  • fix bit_count on arm #25076
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Compose CI / multi cn e2e bvt test docker compose(PESSIMISTIC)
  • check-neutral = Matrixone Compose CI / multi cn e2e bvt test docker compose(PESSIMISTIC)
  • check-skipped = Matrixone Compose CI / multi cn e2e bvt test docker compose(PESSIMISTIC)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Standlone CI / Multi-CN e2e BVT Test on Linux/x64(LAUNCH, PROXY)
  • check-neutral = Matrixone Standlone CI / Multi-CN e2e BVT Test on Linux/x64(LAUNCH, PROXY)
  • check-skipped = Matrixone Standlone CI / Multi-CN e2e BVT Test on Linux/x64(LAUNCH, PROXY)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH, PESSIMISTIC)
  • check-neutral = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH, PESSIMISTIC)
  • check-skipped = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH, PESSIMISTIC)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone CI / SCA Test on Ubuntu/x86
  • check-neutral = Matrixone CI / SCA Test on Ubuntu/x86
  • check-skipped = Matrixone CI / SCA Test on Ubuntu/x86
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone CI / UT Test on Ubuntu/x86
  • check-neutral = Matrixone CI / UT Test on Ubuntu/x86
  • check-skipped = Matrixone CI / UT Test on Ubuntu/x86
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Compose CI / multi cn e2e bvt test docker compose(Optimistic/PUSH)
  • check-neutral = Matrixone Compose CI / multi cn e2e bvt test docker compose(Optimistic/PUSH)
  • check-skipped = Matrixone Compose CI / multi cn e2e bvt test docker compose(Optimistic/PUSH)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH,Optimistic)
  • check-neutral = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH,Optimistic)
  • check-skipped = Matrixone Standlone CI / e2e BVT Test on Linux/x64(LAUNCH,Optimistic)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Upgrade CI / Compatibility Test With Target on Linux/x64(LAUNCH)
  • check-neutral = Matrixone Upgrade CI / Compatibility Test With Target on Linux/x64(LAUNCH)
  • check-skipped = Matrixone Upgrade CI / Compatibility Test With Target on Linux/x64(LAUNCH)
• any of [🛡 GitHub branch protection]:
  • check-success = Matrixone Utils CI / Coverage
  • check-neutral = Matrixone Utils CI / Coverage
  • check-skipped = Matrixone Utils CI / Coverage