[llvm] [InstCombine] Enable FoldOpIntoSelect and foldOpIntoPhi when the Op's other parameter is non-const (PR #166102)

[Nikita Popov via llvm-commits]

================
@@ -2261,11 +2261,11 @@ Instruction *InstCombinerImpl::foldBinopWithPhiOperands(BinaryOperator &BO) {
 }
 
 Instruction *InstCombinerImpl::foldBinOpIntoSelectOrPhi(BinaryOperator &I) {
-  if (!isa<Constant>(I.getOperand(1)))
-    return nullptr;
+  bool IsOtherParamConst = isa<Constant>(I.getOperand(1));
 
   if (auto *Sel = dyn_cast<SelectInst>(I.getOperand(0))) {
----------------
nikic wrote:

This code previously relied on constants being canonicalized to the RHS, so we only had to check for the select on the LHS. However, extended to non-constants, shouldn't we be checking both operands now?

https://github.com/llvm/llvm-project/pull/166102