Ensure we preserve vn and produce a canonical tree#127689
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tannergooding wants to merge 1 commit intodotnet:mainfrom
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Ensure we preserve vn and produce a canonical tree#127689tannergooding wants to merge 1 commit intodotnet:mainfrom
tannergooding wants to merge 1 commit intodotnet:mainfrom
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Pull request overview
This PR updates CoreCLR JIT morphing to (1) preserve value numbering (VN) across a specific MOD -> AND strength-reduction used under ==/!= 0 comparisons, and (2) canonicalize a SUB -> ADD rewrite so the constant ends up as the second operand.
Changes:
- Preserve VN when rewriting
(a % c) ==/!= 0(power-of-2c) intoa & (c - 1) ==/!= 0. - Adjust the
cns1 - op2rewrite to produce((-op2) + cns1)(constant as operand 2). - Update the in-code comment to reflect the intended canonical tree form.
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| tree->AsOp()->gtOp2 = op2 = op1; | ||
| tree->AsOp()->gtOp1 = op1 = gtNewOperNode(GT_NEG, genActualType(op2->TypeGet()), op2); | ||
| fgMorphTreeDone(op2); |
| } | ||
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| /* Check for "cns1 - op2" , we change it to "(cns1 + (-op2))" */ | ||
| /* Check for "cns1 - op2" , we change it to "((-op2) + cns1)" */ |
This was referenced May 3, 2026
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This ensures that we preserve the VN when morphing a particular
MOD->ANDpattern and ensures that a particularSUB->ADDpattern produces a "canonical" tree with the constant as the second operand.