[llvm] [ValueTracking] Add `matchSimpleBinaryIntrinsicRecurrence` helper (PR #145964)

[Nikita Popov via llvm-commits]

================
@@ -9119,6 +9120,28 @@ bool llvm::matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P,
   return P && matchSimpleRecurrence(P, BO, Start, Step) && BO == I;
 }
 
+bool llvm::matchSimpleBinaryIntrinsicRecurrence(const IntrinsicInst *I,
+                                                PHINode *&P, Value *&Init,
+                                                Value *&Invariant) {
+  IntrinsicInst *II = nullptr;
+  P = dyn_cast<PHINode>(I->getArgOperand(0));
+  if (!P)
+    P = dyn_cast<PHINode>(I->getArgOperand(1));
+
+  return P &&
+         matchTwoInputRecurrence<IntrinsicInst>(
+             P, II, Init, Invariant,
+             [](const IntrinsicInst *I) {
+               Intrinsic::ID IID = I->getIntrinsicID();
+               return isa<SaturatingInst, MinMaxIntrinsic>(I) ||
+                      IID == Intrinsic::minnum || IID == Intrinsic::maxnum ||
+                      IID == Intrinsic::minimum || IID == Intrinsic::maximum ||
+                      IID == Intrinsic::minimumnum ||
+                      IID == Intrinsic::maximumnum;
+             }) &&
----------------
nikic wrote:

I don't understand why this function needs to check the intrinsic ID at all. We recently removed the check for opcodes form the BinaryOperator variant, leaving the choice of which intrinsics to support to the caller.

https://github.com/llvm/llvm-project/pull/145964