[Attributor] Use fine-grained liveness in all helpers

We used coarse-grained liveness before, thus we looked if the
instruction was executed, but we did not use fine-grained liveness,
hence if the instruction was needed or could be deleted even if the
surrounding ones are live. This patches introduces this level of
liveness checks together with other liveness queries, e.g., for uses.

For more control we enforce that all liveness queries go through the
Attributor.

Test have been adjusted to reflect the changes or augmented to prevent
deletion of the parts we want to check.

Reviewed By: sstefan1

Differential Revision: https://reviews.llvm.org/D73313

Author: jdoerfert

llvm/include/llvm/Transforms/IPO/Attributor.h

@@ -852,14 +852,41 @@ struct Attributor {
   /// Return true if \p AA (or its context instruction) is assumed dead.
   ///
   /// If \p LivenessAA is not provided it is queried.
-  bool isAssumedDead(const AbstractAttribute &AA, const AAIsDead *LivenessAA);
+  bool isAssumedDead(const AbstractAttribute &AA, const AAIsDead *LivenessAA,
+                     bool CheckBBLivenessOnly = false,
+                     DepClassTy DepClass = DepClassTy::OPTIONAL);
+
+  /// Return true if \p I is assumed dead.
+  ///
+  /// If \p LivenessAA is not provided it is queried.
+  bool isAssumedDead(const Instruction &I, const AbstractAttribute *QueryingAA,
+                     const AAIsDead *LivenessAA,
+                     bool CheckBBLivenessOnly = false,
+                     DepClassTy DepClass = DepClassTy::OPTIONAL);
+
+  /// Return true if \p U is assumed dead.
+  ///
+  /// If \p FnLivenessAA is not provided it is queried.
+  bool isAssumedDead(const Use &U, const AbstractAttribute *QueryingAA,
+                     const AAIsDead *FnLivenessAA,
+                     bool CheckBBLivenessOnly = false,
+                     DepClassTy DepClass = DepClassTy::OPTIONAL);
+
+  /// Return true if \p IRP is assumed dead.
+  ///
+  /// If \p FnLivenessAA is not provided it is queried.
+  bool isAssumedDead(const IRPosition &IRP, const AbstractAttribute *QueryingAA,
+                     const AAIsDead *FnLivenessAA,
+                     bool CheckBBLivenessOnly = false,
+                     DepClassTy DepClass = DepClassTy::OPTIONAL);
 
   /// Check \p Pred on all (transitive) uses of \p V.
   ///
   /// This method will evaluate \p Pred on all (transitive) uses of the
   /// associated value and return true if \p Pred holds every time.
   bool checkForAllUses(const function_ref<bool(const Use &, bool &)> &Pred,
-                       const AbstractAttribute &QueryingAA, const Value &V);
+                       const AbstractAttribute &QueryingAA, const Value &V,
+                       DepClassTy LivenessDepClass = DepClassTy::OPTIONAL);
 
   /// Helper struct used in the communication between an abstract attribute (AA)
   /// that wants to change the signature of a function and the Attributor which
@@ -997,7 +1024,8 @@ struct Attributor {
   /// present in \p Opcode and return true if \p Pred holds on all of them.
   bool checkForAllInstructions(const function_ref<bool(Instruction &)> &Pred,
                                const AbstractAttribute &QueryingAA,
-                               const ArrayRef<unsigned> &Opcodes);
+                               const ArrayRef<unsigned> &Opcodes,
+                               bool CheckBBLivenessOnly = false);
 
   /// Check \p Pred on all call-like instructions (=CallBased derived).
   ///
@@ -2109,6 +2137,10 @@ struct AAIsDead : public StateWrapper<BooleanState, AbstractAttribute>,
                   public IRPosition {
   AAIsDead(const IRPosition &IRP) : IRPosition(IRP) {}
 
+protected:
+  /// The query functions are protected such that other attributes need to go
+  /// through the Attributor interfaces: `Attributor::isAssumedDead(...)`
+
   /// Returns true if the underlying value is assumed dead.
   virtual bool isAssumedDead() const = 0;
 
@@ -2141,6 +2173,7 @@ struct AAIsDead : public StateWrapper<BooleanState, AbstractAttribute>,
     return false;
   }
 
+public:
   /// Return an IR position, see struct IRPosition.
   const IRPosition &getIRPosition() const override { return *this; }
 
@@ -2149,6 +2182,8 @@ struct AAIsDead : public StateWrapper<BooleanState, AbstractAttribute>,
 
   /// Unique ID (due to the unique address)
   static const char ID;
+
+  friend struct Attributor;
 };
 
 /// State for dereferenceable attribute