ffi: preserve uint8 semantics for bool fast calls

[trivikr]

Fixes: #64526

node:ffi documents bool as an 8-bit unsigned integer, but the Fast
API path mapped it to V8's Boolean type. As a result, behavior changed
after JIT optimization:

• return values changed from numbers to JavaScript Booleans;
• true and false became accepted as arguments.

This change normalizes bool to the existing kUint8 Fast FFI type and
removes the now-unused kBool type. The regression test forces V8
optimization and verifies that numeric return values and argument
validation remain consistent.

---

Assisted-by: openai:gpt-5.6-sol

[nodejs-github-bot]

Review requested:

• @nodejs/ffi
• @nodejs/tsc

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.25%. Comparing base (f2ba101) to head (ae0ca8d).
⚠️ Report is 57 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ffi/fast.cc	0.00%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #64527 +/- ##
==========================================
- Coverage 92.01% 90.25% -1.77% 
==========================================
Files 379 739 +360 Lines 170129 241649 +71520 Branches 26090 45542 +19452 ==========================================
+ Hits 156544 218098 +61554 - Misses 13293 15093 +1800 - Partials 292 8458 +8166 

Files with missing lines	Coverage Δ
src/ffi/fast.h	100.00% <ø> (ø)
src/ffi/platforms/arm64.cc	86.90% <ø> (ø)
src/ffi/fast.cc	66.66% <0.00%> (ø)

... and 481 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[ShogunPanda]

Can you please run comparison benchmarks to make sure nothing regresses?

[trivikr]

Can you please run comparison benchmarks to make sure nothing regresses?

Did you mean benchmark-node-micro-benchmarks?

[ShogunPanda]

No, I meant something like:

./node-new --no-warnings --experimental-ffi benchmark/compare.js --old ./node-old --new ./node-new --runs 30 --no-progress ffi > compare.csv

And then

npx node-benchmark-compare compare.csv

Note that you need to compile Node twice, once before and once after your changes.

[trivikr]

Benchmark output for add-u8 which this PR touches

 confidence improvement accuracy (*) (**) (***)ffi/add-u8.js n=10000000 0.75 % ±1.47% ±1.95% ±2.54%

[ShogunPanda]

Do you mind posting the entire benchmark? I just want to make sure there are not regressions elsewhere.

[trivikr]

Full ffi benchmarks (separate run)

 confidence improvement accuracy (*) (**) (***)ffi/add-64.js n=10000000 -0.16 % ±0.55% ±0.73% ±0.95%ffi/add-f32.js n=10000000 -0.23 % ±1.33% ±1.77% ±2.31%ffi/add-f64.js n=10000000 -0.60 % ±4.27% ±5.68% ±7.41%ffi/add-i16.js n=10000000 0.67 % ±0.98% ±1.30% ±1.69%ffi/add-i32.js n=10000000 0.57 % ±5.02% ±6.68% ±8.71%ffi/add-i64.js n=10000000 0.41 % ±2.46% ±3.28% ±4.27%ffi/add-i8.js n=10000000 0.19 % ±1.52% ±2.03% ±2.66%ffi/add-u16.js n=10000000 -0.14 % ±4.44% ±5.92% ±7.71%ffi/add-u64.js n=10000000 -1.19 % ±2.27% ±3.04% ±4.01%ffi/add-u8.js n=10000000 -0.54 % ±1.31% ±1.75% ±2.29%ffi/buffer-first-byte-direct.js n=10000000 -0.00 % ±0.25% ±0.33% ±0.43%ffi/buffer-first-byte.js n=10000000 0.46 % ±1.59% ±2.11% ±2.75%ffi/buffer-sum-direct.js n=10000000 1.45 % ±2.17% ±2.91% ±3.82%ffi/buffer-sum.js n=10000000 0.67 % ±2.53% ±3.38% ±4.42%ffi/getpid.js n=10000000 -2.12 % ±3.19% ±4.30% ±5.70%ffi/identity-i32.js n=10000000 0.33 % ±0.70% ±0.93% ±1.21%ffi/many-args.js n=10000000 -0.04 % ±1.01% ±1.34% ±1.75%ffi/noop-void.js n=10000000 -0.97 % ±4.20% ±5.62% ±7.40%ffi/pointer-bigint.js n=10000000 1.13 % ±2.46% ±3.31% ±4.38%ffi/pointer-buffer-direct.js n=10000000 -0.08 % ±0.66% ±0.88% ±1.14%ffi/pointer-buffer.js n=10000000 0.32 % ±1.20% ±1.62% ±2.13%ffi/pointer-null.js n=10000000 0.34 % ±1.24% ±1.65% ±2.15%ffi/string-equals-hello-buffer-direct.js n=10000000 -0.23 % ±0.34% ±0.45% ±0.59%ffi/string-equals-hello-buffer.js n=10000000 -0.78 % ±2.22% ±2.96% ±3.86%ffi/string-first-char-buffer-direct.js n=10000000 -0.41 % ±0.88% ±1.17% ±1.54%ffi/string-first-char-buffer.js n=10000000 -1.13 % ±1.18% ±1.57% ±2.04%ffi/string-length-buffer-direct.js n=10000000 -1.36 % ±2.46% ±3.31% ±4.37%ffi/string-length-buffer.js n=10000000 0.00 % ±0.35% ±0.46% ±0.60%ffi/string-length-string-direct.js n=10000000 0.04 % ±0.11% ±0.15% ±0.20%ffi/string-length-string.js n=10000000 -1.15 % ±1.92% ±2.55% ±3.33%ffi/sum-3-i32.js n=10000000 0.53 % ±0.81% ±1.07% ±1.40%ffi/sum-5-i32.js n=10000000 0.13 % ±0.83% ±1.10% ±1.44%ffi/sum-8-i32.js n=10000000 0.24 % ±0.35% ±0.46% ±0.60%ffi/sum-buffer.js n=1000000 size=1024 -1.05 % ±2.21% ±2.96% ±3.89%ffi/sum-buffer.js n=1000000 size=16384 -0.13 % ±1.25% ±1.66% ±2.17%ffi/sum-buffer.js n=1000000 size=64 1.87 % ±5.15% ±6.92% ±9.15%

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/75031/

[nodejs-github-bot]

Landed in 0992f6b

[charlenelangley02-cpu]

Thank you Charlene langley

…

On Wed, Jul 22, 2026, 11:36 PM Node.js GitHub Bot ***@***.***> wrote: Merged #64527 <#64527> into main. — Reply to this email directly, view it on GitHub <#64527?email_source=notifications&email_token=BXYHG47AHH5N5GMYDU5ZGVT5GGB4HA5CNFSNUABQM5UWIORPF5TWS5BNNB2WEL2JONZXKZKFOZSW45CON52GSZTJMNQXI2LPNYXTEOBTGYYDSMJRGEZTPJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L#event-28360911137>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BXYHG44U3JYQGXDVDNVYP7D5GGB4HAVCNFSNUABEKJSXA33TNF2G64TZHMZDOMJZGM3TOOJ3JFZXG5LFHM2DQOJYGM4DMNZVGSQXMAQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>