Improve IsKnownConstant - #84002

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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.
It allows to use IsKnownConstant for e.g. spans

@ghostghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Mar 28, 2023
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.
It allows to use IsKnownConstant for e.g. spans

Author:EgorBo
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Comment threadsrc/coreclr/jit/lower.cpp Outdated
Comment threadsrc/coreclr/jit/valuenum.cpp Outdated
Comment on lines +11052 to +11054
bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);

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Seems the implementation with both liberal and conservative VNs was lost along the way...

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Good point, fixed

Comment threadsrc/coreclr/jit/lower.cpp
Comment on lines +7797 to +7798
// IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
// This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)

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This is "not enough"...

Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.

Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.

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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.

I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)

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but the current code is correct, isn't it?

No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.

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but the current code is correct, isn't it?

No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.

Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it

EgorBoand others added 3 commits March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo closed this Mar 28, 2023
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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(){
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var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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Improve IsKnownConstant - #84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
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CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
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Comment threadsrc/coreclr/jit/valuenum.cpp
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Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
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Mar 28, 2023
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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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Improve IsKnownConstant - #84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
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CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
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Comment threadsrc/coreclr/jit/valuenum.cpp
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Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
@EgorBoEgorBoMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
closed this
Mar 28, 2023
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, 'i');
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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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Improve IsKnownConstant - #84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
@ghostghost
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area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
Assignees:-
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Comment threadsrc/coreclr/jit/valuenum.cpp
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Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
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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" + '

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Improve IsKnownConstant - #84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
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CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
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Comment threadsrc/coreclr/jit/valuenum.cpp
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Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
@SingleAccretionSingleAccretionMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
closed this
Mar 28, 2023
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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('^' + ".*" + '

Skip to content
Improve IsKnownConstant - #84002
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EgorBo:improve-isknownconstant
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Improve IsKnownConstant#84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
@ghostghost
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the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
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Comment threadsrc/coreclr/jit/lower.cpp
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Comment threadsrc/coreclr/jit/lower.cpp
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Comment threadsrc/coreclr/jit/valuenum.cpp
Outdated


Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
@EgorBoEgorBoMar 28, 2023

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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
@EgorBoEgorBoMar 28, 2023

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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
@SingleAccretionSingleAccretionMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
@EgorBoEgorBoMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
closed this
Mar 28, 2023
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Mar 28, 2023

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@EgorBo@IDisposable@SingleAccretion

, '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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Improve IsKnownConstant - #84002
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EgorBo:improve-isknownconstant
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Improve IsKnownConstant#84002
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
@ghostghost
added
the 
area-CodeGen-coreclr
CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
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Issue Details
If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
Assignees:-
Labels:
area-CodeGen-coreclr
Milestone:-
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Mar 28, 2023
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Comment threadsrc/coreclr/jit/lower.cpp
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Comment threadsrc/coreclr/jit/valuenum.cpp
Outdated


Comment on lines

+11052
 to 
+11054

 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
@EgorBoEgorBoMar 28, 2023

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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

Comment on lines

+7797
 to 
+7798

 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
@SingleAccretionSingleAccretionMar 28, 2023

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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
@EgorBoEgorBoMar 28, 2023

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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
@SingleAccretionSingleAccretionMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
@EgorBoEgorBoMar 28, 2023

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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
EgorBoand others
added 3 commits
March 28, 2023 20:00
@EgorBo@SingleAccretion
Update src/coreclr/jit/lower.cpp
d4bb2b3
Co-authored-by: SingleAccretion <62474226+SingleAccretion@users.noreply.github.com>
@EgorBo
Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
a8f20d9
…constant
@EgorBo
less conservative VN impl
e473e6d
@EgorBoEgorBo
closed this
Mar 28, 2023
@build-analysisbuild-analysisBot
mentioned this pull request
Mar 28, 2023

Closed

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@EgorBo@IDisposable@SingleAccretion

, '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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Improve IsKnownConstant - #84002
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EgorBo wants to merge 5 commits into
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EgorBo:improve-isknownconstant
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Improve IsKnownConstant#84002
EgorBo wants to merge 5 commits into
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EgorBo:improve-isknownconstant
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
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If we fail to detect a constant in Morph - delegate it to late phases like VN/ConstantProp.

It allows to use IsKnownConstant for e.g. spans
Author:EgorBo
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Comment threadsrc/coreclr/jit/lower.cpp
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Comment threadsrc/coreclr/jit/valuenum.cpp
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 bool isKnownConstant = arg0VNP.BothEqual() && vnStore->IsVNConstant(arg0VNP.GetLiberal());
 ValueNum isCnsVN = vnStore->VNForIntCon(isKnownConstant ? 1 : 0);
 intrinsic->gtVNPair = vnStore->VNPWithExc(ValueNumPair(isCnsVN, isCnsVN), arg0VNPx);
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Seems the implementation with both liberal and conservative VNs was lost along the way...
@EgorBoEgorBoMar 28, 2023

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Good point, fixed
Comment threadsrc/coreclr/jit/lower.cpp

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 // IsKnownConstant is expected to be folded in Importer/Morph/VN+ConstantProp
 // This path is just in case if VN+ConstantProp didn't fold them for some reason (or e.g. they were disabled)
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This is "not enough"...
Consider a case where VN assigns this 1 (i. e. the operand is constant). Then CSE CSEs this as a def with some other unrelated uses of the value 1. Then lowering comes along, and we get 0 instead of 1.
Essentially, each subsequent phase can only further "refine" the value of this intrinsic. The tricky part here is of course that by the time we get to lowering, VNs are no longer valid. So this needs a separate "lower IsKnownConstant" phase, that would use the still-valid VNs. Bit yucky.
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I agree, but the current code is correct, isn't it? it justs conservatively assumes that input is not a constant so we end up in the non-constant path.
I agree that it'd be nice to have a separate phase for such transforms somewhere after assert prop with still valid VNs. Maybe I'll add one eventuallly (and move unrollings there e.g.)
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
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but the current code is correct, isn't it?
No - consider the CSE example. We cannot have this assigned 1 in VN and then lower it to zero.
Ah, I see what you mean. I'll implement it in a separate phase if we find a real use case for it
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Update src/coreclr/jit/lower.cpp
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Merge branch 'main' of github.com:dotnet/runtime into improve-isknown…
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less conservative VN impl
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