[llvm] [InstCombine] Fold `umax/umin(nuw_shl(z, x), nuw_shl(z, y)) -> nuw_shl(z, umax/umin(x, y))` and `umax/umin(nuw_shl(x, z), nuw_shl(y, z)) -> nuw_shl(umax/umin(x, y), z)` (PR #131076)

[Nikita Popov via llvm-commits]

================
@@ -1592,29 +1596,34 @@ foldIntrinsicUsingDistributiveLaws(IntrinsicInst *II,
   if (!leftDistributesOverRight(InnerOpcode, HasNUW, HasNSW, TopLevelOpcode))
     return nullptr;
 
-  assert(II->isCommutative() && Op0->isCommutative() &&
-         "Only inner and outer commutative op codes are supported.");
-
   Value *A = Op0->getOperand(0);
   Value *B = Op0->getOperand(1);
   Value *C = Op1->getOperand(0);
   Value *D = Op1->getOperand(1);
 
-  // Attempts to swap variables such that A always equals C
-  if (A != C && A != D)
-    std::swap(A, B);
-  if (A == C || A == D) {
-    if (A != C)
-      std::swap(C, D);
+  // Attempts to swap variables such that A equals C or B equals D,
+  // if the inner operation is commutative.
+  if (Op0->isCommutative() && A != C && B != D && A == D)
+    std::swap(C, D);
+
+  if (A != C && B != D)
+    return nullptr;
----------------
nikic wrote:

nit: I'd make this an `else { return nullptr }` on the checks below instead.

https://github.com/llvm/llvm-project/pull/131076