[llvm] [SelectOpt] Add support for AShr/LShr operands (PR #118495)

[David Green via llvm-commits]

================
@@ -784,30 +801,53 @@ void SelectOptimizeImpl::collectSelectGroups(BasicBlock &BB,
       bool Inverted = match(Cond, m_Not(m_Value(Cond)));
       return SelectInfo.insert({I, {Cond, false, Inverted, 0}}).first;
     }
-
-    // An Or(zext(i1 X), Y) can also be treated like a select, with condition X
-    // and values Y|1 and Y.
-    if (auto *BO = dyn_cast<BinaryOperator>(I)) {
-      switch (I->getOpcode()) {
-      case Instruction::Add:
-      case Instruction::Sub: {
-        Value *X;
-        if (!((PatternMatch::match(I->getOperand(0),
-                                   m_OneUse(m_ZExt(m_Value(X)))) ||
-               PatternMatch::match(I->getOperand(1),
-                                   m_OneUse(m_ZExt(m_Value(X))))) &&
-              X->getType()->isIntegerTy(1)))
+    Value *Val;
+    ConstantInt *Shift;
+    if (match(I, m_Shr(m_Value(Val), m_ConstantInt(Shift))) &&
+        I->getType()->getIntegerBitWidth() == Shift->getZExtValue() + 1) {
+      for (auto *CmpI : SeenCmp) {
+        auto Pred = CmpI->getPredicate();
+        if (Val != CmpI->getOperand(0))
           return SelectInfo.end();
----------------
davemgreen wrote:

`continue` here to check other icmps in SeenCmp?

https://github.com/llvm/llvm-project/pull/118495