Avoid large table as part of TensorPrimitives remainder mask - #92765

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
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area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
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Avoid large table as part of TensorPrimitives remainder mask - #92765

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

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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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Avoid large table as part of TensorPrimitives remainder mask - #92765

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Avoid large table as part of TensorPrimitives remainder mask#92765
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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

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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 > 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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Avoid large table as part of TensorPrimitives remainder mask - #92765

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

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Avoid large table as part of TensorPrimitives remainder mask - #92765

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

@ghostghost locked as resolved and limited conversation to collaborators Oct 28, 2023
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Avoid large table as part of TensorPrimitives remainder mask - #92765

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

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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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Avoid large table as part of TensorPrimitives remainder mask - #92765

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stephentoub:replaceremaindertable
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Avoid large table as part of TensorPrimitives remainder mask#92765
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stephentoub:replaceremaindertable

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As discussed in #92672 (review)

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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

@ghostghost locked as resolved and limited conversation to collaborators Oct 28, 2023
@stephentoub
stephentoub deleted the replaceremaindertable branch December 12, 2025 23:00
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode"); } } catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); } })(); })();
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Avoid large table as part of TensorPrimitives remainder mask - #92765

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stephentoub wants to merge 1 commit into
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stephentoub:replaceremaindertable
Closed

Avoid large table as part of TensorPrimitives remainder mask#92765
stephentoub wants to merge 1 commit into
dotnet:mainfrom
stephentoub:replaceremaindertable

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As discussed in #92672 (review)

@ghost

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Tagging subscribers to this area: @dotnet/area-system-numerics
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Issue Details

As discussed in #92672 (review)

Author:stephentoub
Assignees:stephentoub
Labels:

area-System.Numerics

Milestone:-

Vector512.LoadUnsafe(
ref Unsafe.As<uint, float>(ref MemoryMarshal.GetReference(RemainderUInt32Mask_16x16)),
(uint)(validItems * 16)); // all sixteen floats in the row
Vector512.ConditionalSelect(

@EgorBoEgorBoSep 28, 2023

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So for AVX512 it'd looked like

varmmask16 mask =(1<<n)-1;varmaskedAnd=Avx512.And(vec1,vec2,mask);

but we decided not to expose mask registers so if we expose these as a public API, we can intrinsify at leas the AVX512 version to be cheap 🙂 if it matters, presumably, performance of handling of trailing elements is not that much important esp for large data.

Comment on lines +1407 to +1410
Vector128.ConditionalSelect(
Vector128.LessThan(Vector128.Create(3, 2, 1, 0), Vector128.Create(validItems)).AsSingle(),
Vector128<float>.AllBitsSet,
Vector128<float>.Zero);

@tannergoodingtannergoodingSep 28, 2023

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This is going to be slower and result in a 128-bit constant (or more for other sizes) emitted at runtime per method this gets inlined into.

I think the table is ultimately better and we can get rid of it longer term using a proper JIT intrinsic.


If we really don't want the table, then achieving this with just a broadcast + comparison should be sufficient, since LessThan already produces a per-element mask of AllBitsSet (true) and Zero (false). You can use GreaterThanOrEqual if you need the mask inverted

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Ok, I'll stick with the table. I was on the fence anyway. Just don't like its bulkiness.

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That is, since TrailingMask wants to handle only trailing elements, it will skip processing the first n items that have already been processed.

So if 2 items remain, you have 3 < 2, 2 < 2, 1 < 2, 0 < 2 which produces Zero, Zero, AllBitsSet, AllBitsSet already

@ghostghost locked as resolved and limited conversation to collaborators Oct 28, 2023
@stephentoub
stephentoub deleted the replaceremaindertable branch December 12, 2025 23:00
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