[InstCombine] refactor matching code for logical ands; NFCI

Separating the matches makes it easier
to enhance for commutative patterns.

Author: rotateright

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -2847,16 +2847,18 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
         return replaceOperand(SI, 0, A);
     }
 
-    // (c && a)  || (!c && b) --> sel c, a, b
-    // (!c && a) ||  (c && b) --> sel c, b, a
-    Value *C1, *C2;
-    if (match(CondVal, m_LogicalAnd(m_Value(C1), m_Value(A))) &&
-        match(TrueVal, m_One()) &&
-        match(FalseVal, m_LogicalAnd(m_Value(C2), m_Value(B)))) {
-      if (match(C2, m_Not(m_Specific(C1)))) // first case
-        return SelectInst::Create(C1, A, B);
-      else if (match(C1, m_Not(m_Specific(C2)))) // second case
-        return SelectInst::Create(C2, B, A);
+    if (match(TrueVal, m_One())) {
+      Value *C;
+
+      // (C && A) || (!C && B) --> sel C, A, B
+      if (match(FalseVal, m_LogicalAnd(m_Not(m_Value(C)), m_Value(B))) &&
+          match(CondVal, m_LogicalAnd(m_Specific(C), m_Value(A))))
+        return SelectInst::Create(C, A, B);
+
+      // (!C && A) || (C && B) --> sel C, B, A
+      if (match(CondVal, m_LogicalAnd(m_Not(m_Value(C)), m_Value(A))) &&
+          match(FalseVal, m_LogicalAnd(m_Specific(C), m_Value(B))))
+        return SelectInst::Create(C, B, A);
     }
   }