GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniacimraniac commented Dec 20, 2025•
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

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pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

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pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all \u003cpre\u003e\u003ccode\u003e blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks"); } } catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); } })(); (function(){ try { var __m = "github.com"; var __re = new RegExp('^' + "github\\.com" + '
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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imraniac:cpp20-use-standard-bit-utils
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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
imraniac wants to merge 1 commit into
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imraniac:cpp20-use-standard-bit-utils

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@imraniac

@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix"); } } catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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imraniac:cpp20-use-standard-bit-utils
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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

@pitrou

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length \u003e 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms"); } } catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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imraniac:cpp20-use-standard-bit-utils
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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniac

@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links"); } } catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); } })(); (function(){ try { var __m = "youtube.com"; var __re = new RegExp('^' + "youtube\\.com" + '
Skip to content

GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

github-actionsBot commented Dec 20, 2025

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

@pitrou

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default"); } } catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

github-actionsBot commented Dec 20, 2025

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers"); } } catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
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@imraniacimraniac commented Dec 20, 2025•
edited by github-actions Bot
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

@github-actions

github-actionsBot commented Dec 20, 2025

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

@pitrou

pitrou commented Feb 18, 2026

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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GH-48591: [C++] Use C++20 standard functions in bit_util.h - #48611

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imraniac:cpp20-use-standard-bit-utils
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GH-48591: [C++] Use C++20 standard functions in bit_util.h#48611
imraniac wants to merge 1 commit into
apache:mainfrom
imraniac:cpp20-use-standard-bit-utils

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@imraniac

@imraniacimraniac commented Dec 20, 2025•
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Rationale for this change

This change replaces custom implementations of bit manipulation functions with C++20 standard library functions from the header. This will reduce the code complexity.

What changes are included in this PR?

Updated the cpp/src/arrow/util/bit_util.h file to replace the custom implementation for PopCount, CountLeadingZeros, and CountTrailingZeros with C++20 standard library functions std::popcount(), std::countl_zero() and std::countr_zero() respectively.

Are these changes tested?

Yes

Are there any user-facing changes?

No, this is an internal refactoring of bit utility functions.

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github-actionsBot commented Dec 20, 2025

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⚠️ GitHub issue #48591has been automatically assigned in GitHub to PR creator.

@pitrou

pitrou commented Jan 12, 2026

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Thanks for the PR @imraniac . This is fine, but I think in general we can simplify a bit further. Two suggestions:

  1. PopCount, CountLeadingZeros and CountTrailingZeros are now trivial wrappers around std functions, so how about we remove those wrappers and call the std functions directly?

  2. NumRequiredBits can similarly be replaced with std::bit_width, can you do this as well?

@pitrou

pitrou commented Jan 12, 2026

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cc @zanmato1984 FYI

@pitrou

pitrou commented Feb 18, 2026

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This PR is obsoleted by #49298, closing.

@pitroupitrou closed this Feb 18, 2026
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