[llvm] [HashRecognize] Track visited in ValueEvolution (PR #147812)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -185,9 +199,14 @@ KnownBits ValueEvolution::computeInstr(const Instruction *I) {
   // Compute the KnownBits for a Select(Cmp()), forcing it to take the branch
   // that is predicated on the (least|most)-significant-bit check.
   CmpPredicate Pred;
-  Value *L, *R, *TV, *FV;
-  if (match(I, m_Select(m_ICmp(Pred, m_Value(L), m_Value(R)), m_Value(TV),
-                        m_Value(FV)))) {
+  Value *L, *R;
+  Instruction *TV, *FV;
+  if (match(I, m_Select(m_ICmp(Pred, m_Value(L), m_Value(R)), m_Instruction(TV),
+                        m_Instruction(FV)))) {
+    Visited.insert(cast<Instruction>(I->getOperand(0)));
+    Visited.insert(TV);
+    Visited.insert(FV);
----------------
artagnon wrote:

We only compute either TV or FV, with the other being a trivial bit-shift: we force the select-cmp to take the branch which is not a trivial bit-shift. I added a clarifying comment near that code.

https://github.com/llvm/llvm-project/pull/147812