[llvm] [InstCombine] Improve handling of `not` and free inversion. (PR #66787)

[Nikita Popov via llvm-commits]

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@@ -233,58 +233,114 @@ class LLVM_LIBRARY_VISIBILITY InstCombiner {
                                                 PatternMatch::m_Value()));
   }
 
-  /// Return true if the specified value is free to invert (apply ~ to).
-  /// This happens in cases where the ~ can be eliminated.  If WillInvertAllUses
-  /// is true, work under the assumption that the caller intends to remove all
-  /// uses of V and only keep uses of ~V.
-  ///
-  /// See also: canFreelyInvertAllUsersOf()
-  static bool isFreeToInvert(Value *V, bool WillInvertAllUses,
-                             unsigned Depth = 0) {
+  /// Return nonnull value if V is free to invert (with condition) regarding
+  /// WillInvertAllUses.
+  /// If Builder is nonnull, it will return a simplified ~V
+  /// If Builder is null, it will return an arbitrary nonnull value (not
+  /// dereferenceable).
+  static Value *getFreelyInverted(Value *V, bool WillInvertAllUses,
+                                  BuilderTy *Builder, unsigned Depth = 0) {
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nikic wrote:

Can you please move the definition of this method out of line? I don't see a reason why this code needs to live in a header.

https://github.com/llvm/llvm-project/pull/66787