[llvm] [LV] Vectorize uncountable early exit store loops with combined conditions (PR #205109)

[Florian Hahn via llvm-commits]

================
@@ -1783,10 +1804,16 @@ bool LoopVectorizationLegality::canUncountableExitConditionLoadBeMoved(
   Instruction *L = nullptr;
   Value *Ptr = nullptr;
   Value *R = nullptr;
-  // The exit-condition load can appear on either side of the icmp.
-  if (!match(Br->getCondition(),
-             m_OneUse(m_c_ICmp(m_OneUse(m_Instruction(L, m_Load(m_Value(Ptr)))),
-                               m_Value(R))))) {
+  if (!match(
+          Br->getCondition(),
----------------
fhahn wrote:

Here it a comment would be helpful to explain what we try to match here. it may also be good to pull out common parts like 

```m_OneUse(m_c_ICmp(
                          m_OneUse(m_Instruction(L, m_Load(m_Value(Ptr)))),
                          m_Value(R))
```

into a sub-matcher variable

https://github.com/llvm/llvm-project/pull/205109