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JIT: Misc if-conversion - #128449

#128449
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jakobbotsch merged 9 commits into
dotnet:maindotnet/runtime:mainfrom
BoyBaykiller:if-conversion-float-foldBoyBaykiller/runtime:if-conversion-float-foldCopy head branch name to clipboard
Jul 13, 2026
Merged

JIT: Misc if-conversion#128449
jakobbotsch merged 9 commits into
dotnet:maindotnet/runtime:mainfrom
BoyBaykiller:if-conversion-float-foldBoyBaykiller/runtime:if-conversion-float-foldCopy head branch name to clipboard

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@BoyBaykiller

@BoyBaykiller BoyBaykiller commented May 21, 2026 •
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  • Allow GT_SELECT for floats, but only temporally for optimizations, not into codegen (for now)
  • Call gtFoldExprConditional, this handles simple folding
  • Add missing GT_SELECT equality, needed because without gtFoldExprConditional asserts
  • Move the 32-bit bailout to after optimizations so that it can still profit from them. Only abort when there were no optimizations done

@BoyBaykiller
* allow SELECTs for float
21098a6 
* call gtFoldExprConditional
* add missing GT_SELECT equality
@github-actions github-actions Bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label May 21, 2026
@dotnet-policy-service dotnet-policy-service Bot added the community-contribution Indicates that the PR has been added by a community member label May 21, 2026
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@tannergooding

tannergooding commented May 21, 2026

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Allow SELECTs for floats (only temporally for optimizations, not into codegen)

There's notably no reason to not allow it into codegen if the input is a floating-point comparison.

Such cases can emit cmpss followed by blendvps, which is smaller than ucomiss; test; jcc; etc

@BoyBaykiller

BoyBaykiller commented May 21, 2026

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That'd be nice to handle. Currently doing that hits assert isGeneralRegister(dstReg) && isGeneralRegister(srcReg) in emitxarch.cpp:7955 so that probably needs some extra work (different PR)

@BoyBaykiller BoyBaykiller reopened this May 24, 2026
@build-analysis build-analysis Bot mentioned this pull request May 24, 2026
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BoyBaykiller marked this pull request as ready for review May 25, 2026 05:31
This was referenced May 25, 2026
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@BoyBaykiller

BoyBaykiller commented May 25, 2026 •
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@jakobbotsch PTAL. A few tiny changes packed in one PR.
Not quite sure how this is supposedly a slight tp improvement diffs.

Next we can look into supporting float-select into codegen. Or adding opts for it.

@BoyBaykiller BoyBaykiller changed the title JIT: Call gtFoldExprConditional in if-conversion and allow float SELECTs JIT: Misc if-conversion Jun 9, 2026
@build-analysis build-analysis Bot mentioned this pull request Jun 9, 2026
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@JulieLeeMSFT
JulieLeeMSFT requested a review from jakobbotsch July 6, 2026 15:42
@jakobbotsch
jakobbotsch merged commit 3df37a7 into dotnet:main Jul 13, 2026
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@dotnet-maestro dotnet-maestro Bot mentioned this pull request Jul 14, 2026
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@dotnet-milestone-bot dotnet-milestone-bot Bot added this to the 11.0-preview7 milestone Jul 14, 2026
eiriktsarpalis pushed a commit that referenced this pull request Jul 15, 2026
@BoyBaykiller @eiriktsarpalis
JIT: Misc if-conversion (#128449)
92c8dac 
* Allow GT_SELECT for floats, but only temporally for optimizations, not
into codegen (for now)
* Call `gtFoldExprConditional`, this handles simple folding
* Add missing `GT_SELECT` equality, needed because without
`gtFoldExprConditional` asserts
* Move the 32-bit bailout to after optimizations so that it can still
profit from them. Only abort when there were no optimizations done
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