Possible optimisation for derefencing a span pointer #80086

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Possible optimisation for derefencing a span pointer#80086
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markples
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Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
Milestone
8.0.0

Description

@hamarb123
hamarb123
opened on Dec 31, 2022

Description

Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)

Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.

There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).

Regression?

No afaik

Analysis

I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).

Apparently this is a known issue, but there is no open issue for it.

The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===

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Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue

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    , 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
     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" + '

    Skip to content
    Possible optimisation for derefencing a span pointer #80086
    Closed
    Closed
    Possible optimisation for derefencing a span pointer#80086
    Assignees
    markples
    Labels
    Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
    Milestone
    8.0.0
    Description
    @hamarb123
    hamarb123
    opened on Dec 31, 2022
    Description
    Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
    Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
    There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
    Regression?
    No afaik
    Analysis
    I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
    Apparently this is a known issue, but there is no open issue for it.
    The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
    Metadata
    Metadata
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    Labels
    Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
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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('^' + ".*" + '

      Skip to content
      Possible optimisation for derefencing a span pointer #80086
      Closed
      Closed
      Possible optimisation for derefencing a span pointer#80086
      Assignees
      markples
      Labels
      Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
      Milestone
      8.0.0
      Description
      @hamarb123
      hamarb123
      opened on Dec 31, 2022
      Description
      Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
      Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
      There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
      Regression?
      No afaik
      Analysis
      I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
      Apparently this is a known issue, but there is no open issue for it.
      The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
      Metadata
      Metadata
      Assignees
      Labels
      Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
      Type
      No type
      Projects
      No projects
        Milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, '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('^' + ".*" + '

        Skip to content
        Possible optimisation for derefencing a span pointer #80086
        Closed
        Closed
        Possible optimisation for derefencing a span pointer#80086
        Assignees
        markples
        Labels
        Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
        Milestone
        8.0.0
        Description
        @hamarb123
        hamarb123
        opened on Dec 31, 2022
        Description
        Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
        Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
        There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
        Regression?
        No afaik
        Analysis
        I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
        Apparently this is a known issue, but there is no open issue for it.
        The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
        Metadata
        Metadata
        Assignees
        Labels
        Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
        Type
        No type
        Projects
        No projects
          Milestone
          Relationships
          None yet
          Development
          No branches or pull requests
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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
          Possible optimisation for derefencing a span pointer #80086
          Closed
          Closed
          Possible optimisation for derefencing a span pointer#80086
          Assignees
          markples
          Labels
          Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
          Milestone
          8.0.0
          Description
          @hamarb123
          hamarb123
          opened on Dec 31, 2022
          Description
          Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
          Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
          There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
          Regression?
          No afaik
          Analysis
          I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
          Apparently this is a known issue, but there is no open issue for it.
          The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
          Metadata
          Metadata
          Assignees
          Labels
          Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
          Type
          No type
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          No projects
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            None yet
            Development
            No branches or pull requests
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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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            Possible optimisation for derefencing a span pointer #80086
            Closed
            Closed
            Possible optimisation for derefencing a span pointer#80086
            Assignees
            markples
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            Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
            Milestone
            8.0.0
            Description
            @hamarb123
            hamarb123
            opened on Dec 31, 2022
            Description
            Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
            Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
            There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
            Regression?
            No afaik
            Analysis
            I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
            Apparently this is a known issue, but there is no open issue for it.
            The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
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            Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
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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('^' + ".*" + '

              Skip to content
              Possible optimisation for derefencing a span pointer #80086
              Closed
              Closed
              Possible optimisation for derefencing a span pointer#80086
              Assignees
              markples
              Labels
              Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
              Milestone
              8.0.0
              Description
              @hamarb123
              hamarb123
              opened on Dec 31, 2022
              Description
              Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
              Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
              There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
              Regression?
              No afaik
              Analysis
              I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
              Apparently this is a known issue, but there is no open issue for it.
              The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
              Metadata
              Metadata
              Assignees
              Labels
              Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
              Type
              No type
              Projects
              No projects
                Milestone
                Relationships
                None yet
                Development
                No branches or pull requests
                Issue actions
                
, '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); }
})();
})();

                Skip to content
                Possible optimisation for derefencing a span pointer #80086
                Closed
                Closed
                Possible optimisation for derefencing a span pointer#80086
                Assignees
                markples
                Labels
                Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
                Milestone
                8.0.0
                Description
                @hamarb123
                hamarb123
                opened on Dec 31, 2022
                Description
                Dereferencing a pointer to a span seems to be unoptimised, see the codegen for M2 vs M1https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKGIAYACY8gOgCUBXAOwwEt8YLAJI8YUCAAcAymIBuvMDFwBuGjWIBmBt1zYAZjCakGAYRoBvGg2tMtzJAykTsXADy8eAPgYBZcgAonF3cvACoGbABKKxtLahsEpgB2Xxh8aABPH2woXAALbAAbFhNYbAwYIK5/WD1U9KgsnPyilgBxGAw2GANYLkV/UKi0CLhPABkYLgBzDDzI1XibAF8Y600mcgcqkIxvH1JA5zcPPfCotYY4xJtiFKHFhNXqZ6A=== (thanks @tannergooding for this code, it was not obvious to me this would result in better codegen)
                Clearly, it could be theoretically as good as M1 since they do the same thing, but it's not.
                There are valid reasons for taking a pointer to a span (and other ref structs), e.g. calling string.Create with some span data, since it can't be used as the TState generic parameter, the only real choice is to pass it by pointer or to copy the data (which is obviously much slower).
                Regression?
                No afaik
                Analysis
                I've been informed that the call 0x00007ffaff64e850 (address may vary) is a write barrier (thanks @SingleAccretion).
                Apparently this is a known issue, but there is no open issue for it.
                The same poor codegen doesn't seem to exist for reference types and normal value types: https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKAEoxsAEwDyrADYBPBUrUbt2AJSjxI6uO+8A7IwAqfXsVdS0AlwAybABudzEAX3iJXmlUgAZdUn0IYAArGDAMRldkzx9xYn8gqXSI6LivcSSmsQZUmWYw3Xp9btLWxnKKv0D9Lo162OSWlqA=== and https://sharplab.io/#v2:EYLgxg9gTgpgtADwGwBYA0AXEBDAzgWwB8ABAJgEYBYAKBuIGYACAVwDtdsAzGRsxgYRoBvGozG8mxckkYBlAA7ZWAHgCWrDAD5GAWXIAKBUrUbNAKkbYAlKPEjq4x7wDsjM9gDctsQF9vE3mlGCGAAKxgwDF1SfRDwyItrf3sncWJXdy8HcT9ssQZAmWZ1KJ16fWKNRJs8xhTUlzdPf1zcoA===
                Metadata
                Metadata
                Assignees
                Labels
                Priority:2Work that is important, but not critical for the releasearea-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIbugin-prThere is an active PR which will close this issue when it is mergedtenet-performancePerformance related issue
                Type
                No type
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                No projects
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                  None yet
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                  No branches or pull requests
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