[llvm] db04516 - [SCEV] Introduce getOrCreateUDivExpr (NFC) (#216832)

[via llvm-commits]

Author: Ramkumar Ramachandra
Date: 2026-08-18T13:07:45Z
New Revision: db04516141349e6043d61019097b11ddec558b85

URL: https://github.com/llvm/llvm-project/commit/db04516141349e6043d61019097b11ddec558b85
DIFF: https://github.com/llvm/llvm-project/commit/db04516141349e6043d61019097b11ddec558b85.diff

LOG: [SCEV] Introduce getOrCreateUDivExpr (NFC) (#216832)

Avoid error-prone munging SCEVUses in place in getUDivExpr, and allocate
the operands uniformly in a new getOrCreateUDivExpr.

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 4e1aeea26f943..713d0dd2f9b0e 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -2515,6 +2515,9 @@ class ScalarEvolution {
   const SCEV *getOrCreateAddRecExpr(ArrayRef<SCEVUse> Ops, const Loop *L,
                                     SCEV::NoWrapFlags Flags);
 
+  // Get UDiv expression already created or create a new one.
+  const SCEV *getOrCreateUDivExpr(SCEVUse LHS, SCEVUse RHS);
+
   /// Return x if \p Val is f(x) where f is a 1-1 function.
   const SCEV *stripInjectiveFunctions(const SCEV *Val) const;
 

diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index dab6f9a4e00f3..467714dd1cb50 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -3096,6 +3096,22 @@ const SCEV *ScalarEvolution::getOrCreateMulExpr(ArrayRef<SCEVUse> Ops,
   return S;
 }
 
+const SCEV *ScalarEvolution::getOrCreateUDivExpr(SCEVUse LHS, SCEVUse RHS) {
+  FoldingSetNodeID ID;
+  ID.AddInteger(scUDivExpr);
+  ID.AddPointer(LHS);
+  ID.AddPointer(RHS);
+  void *IP = nullptr;
+  SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP);
+  if (!S) {
+    S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator), LHS, RHS);
+    UniqueSCEVs.InsertNode(S, IP);
+    S->computeAndSetCanonical(*this);
+    registerUser(S, ArrayRef<SCEVUse>({LHS, RHS}));
+  }
+  return S;
+}
+
 static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
   uint64_t k = i*j;
   if (j > 1 && k / j != i) Overflow = true;
@@ -3489,12 +3505,8 @@ const SCEV *ScalarEvolution::getUDivExpr(SCEVUse LHS, SCEVUse RHS) {
   assert(LHS->getType() == RHS->getType() &&
          "SCEVUDivExpr operand types don't match!");
 
-  FoldingSetNodeID ID;
-  ID.AddInteger(scUDivExpr);
-  ID.AddPointer(LHS);
-  ID.AddPointer(RHS);
-  void *IP = nullptr;
-  if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
+  if (SCEV *S =
+          findExistingSCEVInCache(scUDivExpr, ArrayRef<SCEVUse>({LHS, RHS})))
     return S;
 
   // 0 udiv Y == 0
@@ -3562,19 +3574,8 @@ const SCEV *ScalarEvolution::getUDivExpr(SCEVUse LHS, SCEVUse RHS) {
               const SCEV *NewLHS =
                   getAddRecExpr(NewStart, Step, AR->getLoop(),
                                 NoWrap ? SCEV::FlagNW : SCEV::FlagAnyWrap);
-              if (LHS != NewLHS) {
-                LHS = NewLHS;
-
-                // Reset the ID to include the new LHS, and check if it is
-                // already cached.
-                ID.clear();
-                ID.AddInteger(scUDivExpr);
-                ID.AddPointer(LHS);
-                ID.AddPointer(RHS);
-                IP = nullptr;
-                if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
-                  return S;
-              }
+              if (LHS != NewLHS)
+                return getUDivExpr(NewLHS, RHS);
             }
           }
         }
@@ -3698,16 +3699,7 @@ const SCEV *ScalarEvolution::getUDivExpr(SCEVUse LHS, SCEVUse RHS) {
       match(RHS, m_scev_c_NUWMul(m_SCEV(NewRHS), m_SCEVVScale())))
     return getUDivExpr(NewLHS, NewRHS);
 
-  // The Insertion Point (IP) might be invalid by now (due to UniqueSCEVs
-  // changes). Make sure we get a new one.
-  IP = nullptr;
-  if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
-  SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
-                                             LHS, RHS);
-  UniqueSCEVs.InsertNode(S, IP);
-  S->computeAndSetCanonical(*this);
-  registerUser(S, ArrayRef<SCEVUse>({LHS, RHS}));
-  return S;
+  return getOrCreateUDivExpr(LHS, RHS);
 }
 
 APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {