[llvm] [InstCombine] Remove some of the complexity-based canonicalization (PR #91185)

[via llvm-commits]

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@@ -132,21 +132,18 @@ class LLVM_LIBRARY_VISIBILITY InstCombiner {
   /// This routine maps IR values to various complexity ranks:
   ///   0 -> undef
   ///   1 -> Constants
-  ///   2 -> Other non-instructions
-  ///   3 -> Arguments
-  ///   4 -> Cast and (f)neg/not instructions
-  ///   5 -> Other instructions
+  ///   2 -> Cast and (f)neg/not instructions
+  ///   3 -> Other instructions and arguments
   static unsigned getComplexity(Value *V) {
-    if (isa<Instruction>(V)) {
-      if (isa<CastInst>(V) || match(V, m_Neg(PatternMatch::m_Value())) ||
-          match(V, m_Not(PatternMatch::m_Value())) ||
-          match(V, m_FNeg(PatternMatch::m_Value())))
-        return 4;
-      return 5;
-    }
-    if (isa<Argument>(V))
-      return 3;
-    return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
+    if (isa<Constant>(V))
+      return isa<UndefValue>(V) ? 0 : 1;
+
+    if (isa<CastInst>(V) || match(V, m_Neg(PatternMatch::m_Value())) ||
+        match(V, m_Not(PatternMatch::m_Value())) ||
+        match(V, m_FNeg(PatternMatch::m_Value())))
+      return 2;
+
+    return 3;
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goldsteinn wrote:

Do we also need to change the ordering of `cast/not/neg` vs other instructions?
Also, is the diff cleaner if you keep the original values but just drop the `isa<Argument>(V)` case?

https://github.com/llvm/llvm-project/pull/91185