[llvm] bed163e - [SCEV] Clarify nuw/nsw semantics for multi-operand nodes (#195826)

[via llvm-commits]

Author: Nikita Popov
Date: 2026-05-05T17:26:54+02:00
New Revision: bed163e8ac77c0cf105ab869f5448758b56bed15

URL: https://github.com/llvm/llvm-project/commit/bed163e8ac77c0cf105ab869f5448758b56bed15
DIFF: https://github.com/llvm/llvm-project/commit/bed163e8ac77c0cf105ab869f5448758b56bed15.diff

LOG: [SCEV] Clarify nuw/nsw semantics for multi-operand nodes (#195826)

nuw/nsw must hold for all subsets/orders of operands.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/ScalarEvolution.h

Removed: 
    


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diff  --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 5c01da0855f66..54ea8dbe56dd6 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -72,7 +72,9 @@ LLVM_ABI extern bool VerifySCEV;
 /// Add and Mul expressions may have no-unsigned-wrap <NUW> or
 /// no-signed-wrap <NSW> properties, which are derived from the IR
 /// operator. NSW is a misnomer that we use to mean no signed overflow or
-/// underflow.
+/// underflow. NUW and NSW must hold for all subsets and orders of
+/// Add/Mul operands. That is, in `(a + b + c)<nsw>`, all of `a + b`,
+/// `b + c`, `a + c` must be nsw as well.
 ///
 /// AddRec expressions may have a no-self-wraparound <NW> property if, in
 /// the integer domain, abs(step) * max-iteration(loop) <=