[llvm] [SCEV] Use makeExactNoWrapRegion for constant operands. (NFC) (PR #223973)

[Florian Hahn via llvm-commits]

https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/223973

>From 1f589df3d72245de1399ec0d695fe40de8cebc65 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Mon, 14 Sep 2026 09:51:31 +0100
Subject: [PATCH] [SCEV] Use makeExactNoWrapRegion for constant operands. (NFC)

Use makeExactNoWrapRegion when constant is available.

Together with https://github.com/llvm/llvm-project/pull/223969, this
reduces compile-time in SCEV heavy workloads:

stage1-O3: -0.08%
stage1-ReleaseThinLTO: -0.07%
stage1-ReleaseLTO-g: -0.08%
stage1-aarch64-O3: -0.08%
stage2-O3: -0.07%

https://llvm-compile-time-tracker.com/compare.php?from=e78970f80f1041de8948cb0b665a9aaae682f6c6&to=eeb18333a66b5df7fa3702d6f996260785d96a94&stat=instructions%3Au
---
 llvm/lib/Analysis/ScalarEvolution.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 689a8741af983..ae9fcf9a115c7 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -2472,16 +2472,16 @@ static SCEV::NoWrapFlags StrengthenNoWrapFlags(ScalarEvolution *SE,
 
     // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow.
     if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
-      auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
-          Opcode, C, OBO::NoSignedWrap);
+      auto NSWRegion =
+          ConstantRange::makeExactNoWrapRegion(Opcode, C, OBO::NoSignedWrap);
       if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
         Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
     }
 
     // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow.
     if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
-      auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
-          Opcode, C, OBO::NoUnsignedWrap);
+      auto NUWRegion =
+          ConstantRange::makeExactNoWrapRegion(Opcode, C, OBO::NoUnsignedWrap);
       if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
         Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
     }