[llvm] [InstCombine] Fold `(x == y) ? 0 : (x > y ? 1 : -1)` into `ucmp/scmp(x,y)` (PR #107314)

[Nikita Popov via llvm-commits]

================
@@ -3575,6 +3573,32 @@ Instruction *InstCombinerImpl::foldSelectToCmp(SelectInst &SI) {
        ICmpInst::getSwappedPredicate(ExtendedCmpPredicate) == Pred))
     Replace = true;
 
+  // (x == y) ? 0 : (x > y ? 1 : -1)
+  ICmpInst::Predicate FalseBranchSelectPredicate;
+  ConstantInt *InnerTV, *InnerFV;
+  if (Pred == ICmpInst::ICMP_EQ && match(TV, m_Zero()) &&
+      match(FV, m_Select(m_c_ICmp(FalseBranchSelectPredicate, m_Specific(LHS),
+                                  m_Specific(RHS)),
+                         m_ConstantInt(InnerTV), m_ConstantInt(InnerFV)))) {
----------------
nikic wrote:

m_ConstantInt -> m_APInt. m_ConstantInt doesn't support vectors. Can you please also add a vector test?

https://github.com/llvm/llvm-project/pull/107314