[Attributor] Use structured deduction for AADereferenceable

[jdoerfert]

Summary

This is analogous to D66128 but for AADereferenceable. We have the logic
concentrated in the floating value updateImpl and we use the combiner
helper classes for arguments and return values.

The regressions will go away with "on-demand" attribute creation.
Improvements are already visible in the existing tests.

[uenoku]

LGTM

[uenoku]

llvm/lib/Transforms/IPO/Attributor.cpp

2067

semicolon

llvm/lib/Transforms/IPO/Attributor.cpp

auto VisitValueCB = [&](Value &V, AAAlign::StateType &T,
         T.indicatePessimisticFixpoint();
       }
       return T.isValidState();
     };
 
     StateType T;
     if (!genericValueTraversal<AANonNull, StateType>(A, getIRPosition(), *this,
                                                      T, VisitValueCB))
-      indicatePessimisticFixpoint();
+      return indicatePessimisticFixpoint();
 
     return clampStateAndIndicateChange(getState(), T);
   }
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(nonnull) }
 };
 
struct DerefState : AbstractState {
   /// See IntegerState::operator|=
   DerefState operator|=(const DerefState &R) {
     DerefBytesState |= R.DerefBytesState;
     GlobalState |= R.GlobalState;
     return *this;
   }
 };
 
+template <>
+ChangeStatus clampStateAndIndicateChange<DerefState>(DerefState &S,
+                                                     const DerefState &R) {
+  ChangeStatus CS0 = clampStateAndIndicateChange<IntegerState>(
+      S.DerefBytesState, R.DerefBytesState);
+  ChangeStatus CS1 =
+      clampStateAndIndicateChange<IntegerState>(S.GlobalState, R.GlobalState);
+  return CS0 | CS1;
+}
+
 struct AADereferenceableImpl : AADereferenceable, DerefState {
   AADereferenceableImpl(const IRPosition &IRP) : AADereferenceable(IRP) {}
   using StateType = DerefState;
 
   void initialize(Attributor &A) override {
     SmallVector<Attribute, 4> Attrs;
     getAttrs({Attribute::Dereferenceable, Attribute::DereferenceableOrNull},
              Attrs);
void getDeducedAttributes(LLVMContext &Ctx,
     // TODO: Add *_globally support
     if (isAssumedNonNull())
       Attrs.emplace_back(Attribute::getWithDereferenceableBytes(
           Ctx, getAssumedDereferenceableBytes()));
     else
       Attrs.emplace_back(Attribute::getWithDereferenceableOrNullBytes(
           Ctx, getAssumedDereferenceableBytes()));
   }
-  uint64_t computeAssumedDerefenceableBytes(Attributor &A, Value &V,
-                                            bool &IsGlobal);
 
   /// See AbstractAttribute::getAsStr().
   const std::string getAsStr() const override {
     if (!getAssumedDereferenceableBytes())
       return "unknown-dereferenceable";
     return std::string("dereferenceable") +
            (isAssumedNonNull() ? "" : "_or_null") +
            (isAssumedGlobal() ? "_globally" : "") + "<" +
            std::to_string(getKnownDereferenceableBytes()) + "-" +
            std::to_string(getAssumedDereferenceableBytes()) + ">";
   }
 
 private:
   const AANonNull *NonNullAA = nullptr;
 };
 
-struct AADereferenceableReturned final : AADereferenceableImpl {
-  AADereferenceableReturned(const IRPosition &IRP)
+/// Dereferenceable attribute for a floating value.
+struct AADereferenceableFloating : AADereferenceableImpl {
+  AADereferenceableFloating(const IRPosition &IRP)
       : AADereferenceableImpl(IRP) {}
 
   /// See AbstractAttribute::updateImpl(...).
-  ChangeStatus updateImpl(Attributor &A) override;
-
-  /// See AbstractAttribute::trackStatistics()
-  void trackStatistics() const override {
-    STATS_DECLTRACK_FNRET_ATTR(dereferenceable)
-  }
-};
-
-// Helper function that returns dereferenceable bytes.
-static uint64_t calcDifferenceIfBaseIsNonNull(int64_t DerefBytes,
-                                              int64_t Offset, bool IsNonNull) {
-  if (!IsNonNull)
-    return 0;
-  return std::max((int64_t)0, DerefBytes - Offset);
-}
-
-uint64_t
-AADereferenceableImpl::computeAssumedDerefenceableBytes(Attributor &A, Value &V,
-                                                        bool &IsGlobal) {
-  // TODO: Tracking the globally flag.
-  IsGlobal = false;
-
-  // First, we try to get information about V from Attributor.
-  if (auto *DerefAA =
-          A.getAAFor<AADereferenceable>(*this, IRPosition::value(V))) {
-    return DerefAA->getAssumedDereferenceableBytes();
-  }
-
-  // Otherwise, we try to compute assumed bytes from base pointer.
+  ChangeStatus updateImpl(Attributor &A) override {
     const DataLayout &DL = A.getDataLayout();
+
+    auto VisitValueCB = [&](Value &V, DerefState &T, bool Stripped) -> bool {
       unsigned IdxWidth =
           DL.getIndexSizeInBits(V.getType()->getPointerAddressSpace());
       APInt Offset(IdxWidth, 0);
-  Value *Base = V.stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
+      const Value *Base =
+          V.stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
 
-  if (auto *BaseDerefAA =
-          A.getAAFor<AADereferenceable>(*this, IRPosition::value(*Base))) {
-    return calcDifferenceIfBaseIsNonNull(
-        BaseDerefAA->getAssumedDereferenceableBytes(), Offset.getSExtValue(),
-        Offset != 0 || BaseDerefAA->isAssumedNonNull());
+      const auto *AA =
+            A.getAAFor<AADereferenceable>(*this, IRPosition::value(*Base));
+      int64_t DerefBytes = 0;
+      if (!AA || (!Stripped &&
+                  getIRPosition().getPositionKind() == IRPosition::IRP_FLOAT)) {
+        // Use IR information if we did not strip anything.
+        // TODO: track globally.
+        bool CanBeNull;
+        DerefBytes = Base->getPointerDereferenceableBytes(DL, CanBeNull);
+        T.GlobalState.indicatePessimisticFixpoint();
+      } else {
+        const DerefState &DS = static_cast<const DerefState &>(AA->getState());
+        DerefBytes = DS.DerefBytesState.getAssumed();
+        T.GlobalState &= DS.GlobalState;
       }
 
-  // Then, use IR information.
-
-  if (isDereferenceablePointer(Base, Base->getType(), DL))
-    return calcDifferenceIfBaseIsNonNull(
-        DL.getTypeStoreSize(Base->getType()->getPointerElementType()),
-        Offset.getSExtValue(),
-        !NullPointerIsDefined(getAnchorScope(),
-                              V.getType()->getPointerAddressSpace()));
+      T.takeAssumedDerefBytesMinimum(
+          std::max(int64_t(0), DerefBytes - Offset.getSExtValue()));
 
-  return 0;
+      if (!Stripped &&
+          getIRPosition().getPositionKind() == IRPosition::IRP_FLOAT) {
+        T.takeKnownDerefBytesMaximum(
+            std::max(int64_t(0), DerefBytes - Offset.getSExtValue()));
+        T.indicatePessimisticFixpoint();
       }
 
-ChangeStatus AADereferenceableReturned::updateImpl(Attributor &A) {
-  auto BeforeState = static_cast<DerefState>(*this);
-
-  bool IsGlobal = isAssumedGlobal();
-
-  auto CheckReturnValue = [&](Value &RV) -> bool {
-    takeAssumedDerefBytesMinimum(
-        computeAssumedDerefenceableBytes(A, RV, IsGlobal));
-    return isValidState();
+      return T.isValidState();
     };
 
-  if (A.checkForAllReturnedValues(CheckReturnValue, *this)) {
-    GlobalState.intersectAssumedBits(IsGlobal);
-    return BeforeState == static_cast<DerefState>(*this)
-               ? ChangeStatus::UNCHANGED
-               : ChangeStatus::CHANGED;
-  }
+    DerefState T;
+    if (!genericValueTraversal<AADereferenceable, DerefState>(
+            A, getIRPosition(), *this, T, VisitValueCB))
       return indicatePessimisticFixpoint();
-}
-
-struct AADereferenceableArgument final : AADereferenceableImpl {
-  AADereferenceableArgument(const IRPosition &IRP)
-      : AADereferenceableImpl(IRP) {}
 
-  /// See AbstractAttribute::updateImpl(...).
-  ChangeStatus updateImpl(Attributor &A) override;
+    return clampStateAndIndicateChange(getState(), T);
+  }
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override {
-    STATS_DECLTRACK_ARG_ATTR(dereferenceable)
+    STATS_DECLTRACK_FLOATING_ATTR(dereferenceable)
   }
 };
 
-ChangeStatus AADereferenceableArgument::updateImpl(Attributor &A) {
-  Argument &Arg = cast<Argument>(getAnchorValue());
-
-  auto BeforeState = static_cast<DerefState>(*this);
-
-  unsigned ArgNo = Arg.getArgNo();
-
-  bool IsGlobal = isAssumedGlobal();
-
-  // Callback function
-  std::function<bool(CallSite)> CallSiteCheck = [&](CallSite CS) -> bool {
-    assert(CS && "Sanity check: Call site was not initialized properly!");
+/// Dereferenceable attribute for a return value.
+struct AADereferenceableReturned final
+    : AAReturnedFromReturnedValues<AADereferenceableImpl> {
+  AADereferenceableReturned(const IRPosition &IRP)
+      : AAReturnedFromReturnedValues<AADereferenceableImpl>(IRP) {}
 
-    // Check that DereferenceableAA is AADereferenceableCallSiteArgument.
-    if (auto *DereferenceableAA = A.getAAFor<AADereferenceable>(
-            *this, IRPosition::callsite_argument(CS, ArgNo))) {
-      ImmutableCallSite ICS(
-          &DereferenceableAA->getIRPosition().getAnchorValue());
-      if (ICS && CS.getInstruction() == ICS.getInstruction()) {
-        takeAssumedDerefBytesMinimum(
-            DereferenceableAA->getAssumedDereferenceableBytes());
-        IsGlobal &= DereferenceableAA->isAssumedGlobal();
-        return isValidState();
-      }
-    }
-
-    takeAssumedDerefBytesMinimum(computeAssumedDerefenceableBytes(
-        A, *CS.getArgOperand(ArgNo), IsGlobal));
-
-    return isValidState();
-  };
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override {
+    STATS_DECLTRACK_FNRET_ATTR(dereferenceable)
 
-  if (!A.checkForAllCallSites(CallSiteCheck, *this, true))
-    return indicatePessimisticFixpoint();
-
-  GlobalState.intersectAssumedBits(IsGlobal);
+/// Dereferenceable attribute for an argument
+struct AADereferenceableArgument final
+    : AAArgumentFromCallSiteArguments<AADereferenceableImpl> {
+  AADereferenceableArgument(const IRPosition &IRP)
+      : AAArgumentFromCallSiteArguments<AADereferenceableImpl>(IRP) {}
 
-  return BeforeState == static_cast<DerefState>(*this) ? ChangeStatus::UNCHANGED
-                                                       : ChangeStatus::CHANGED;
-}
+  /// See AbstractAttribute::trackStatistics()
+  void trackStatistics() const override{
+      STATS_DECLTRACK_ARG_ATTR(dereferenceable)};
+};
 
 /// Dereferenceable attribute for a call site argument.
-struct AADereferenceableCallSiteArgument final : AADereferenceableImpl {
+struct AADereferenceableCallSiteArgument final : AADereferenceableFloating {
   AADereferenceableCallSiteArgument(const IRPosition &IRP)
-      : AADereferenceableImpl(IRP) {}
-
-  /// See AbstractAttribute::updateImpl(Attributor &A).
-  ChangeStatus updateImpl(Attributor &A) override;
+      : AADereferenceableFloating(IRP) {}
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override {
     STATS_DECLTRACK_CSARG_ATTR(dereferenceable)
   }
 };
 
-ChangeStatus AADereferenceableCallSiteArgument::updateImpl(Attributor &A) {
-  // NOTE: Never look at the argument of the callee in this method.
-  //       If we do this, "dereferenceable" is always deduced because of the
-  //       assumption.
-
-  Value &V = getAssociatedValue();
-
-  auto BeforeState = static_cast<DerefState>(*this);
-
-  bool IsGlobal = isAssumedGlobal();
-
-  takeAssumedDerefBytesMinimum(
-      computeAssumedDerefenceableBytes(A, V, IsGlobal));
-  GlobalState.intersectAssumedBits(IsGlobal);
-
-  return BeforeState == static_cast<DerefState>(*this) ? ChangeStatus::UNCHANGED
-                                                       : ChangeStatus::CHANGED;
-}
-
 /// Dereferenceable attribute deduction for a call site return value.
 using AADereferenceableCallSiteReturned = AADereferenceableReturned;
 
 // ------------------------ Align Argument Attribute ------------------------
 
 struct AAAlignImpl : AAAlign {
   AAAlignImpl(const IRPosition &IRP) : AAAlign(IRP) {}
 
auto VisitValueCB = [&](Value &V, AAAlign::StateType &T,
         T.indicatePessimisticFixpoint();
       }
       return T.isValidState();
     };
 
     StateType T;
     if (!genericValueTraversal<AAAlign, StateType>(A, getIRPosition(), *this, T,
                                                    VisitValueCB))
-      indicatePessimisticFixpoint();
+      return indicatePessimisticFixpoint();
 
     return clampStateAndIndicateChange(getState(), T);
   }
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override { STATS_DECLTRACK_FLOATING_ATTR(align) }
 };
 

llvm/test/Transforms/FunctionAttrs/align.ll

 @a1 = common global i8 0, align 8
 @a2 = common global i8 0, align 16
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f1(i8* readnone %0) local_unnamed_addr #0 {
 ; FIXME: Until we have "on-demand" attribute generation we do not determine the
 ;        alignment for the return value here.
 ;             define internal nonnull align 8 i8* @f1(i8* nonnull readnone align 8 %0)
-; ATTRIBUTOR: define internal i8* @f1(i8* nonnull readnone align 8 %0)
+; ATTRIBUTOR: define internal i8* @f1(i8* nonnull readnone align 8 dereferenceable(1) %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %3, label %5
 
 ; <label>:3:                                      ; preds = %1
-; ATTRIBUTOR: %4 = tail call i8* @f2(i8* nonnull align 8 @a1)
+; ATTRIBUTOR: %4 = tail call i8* @f2(i8* nonnull align 8 dereferenceable(1) @a1)
   %4 = tail call i8* @f2(i8* nonnull @a1)
   br label %5
 
 ; <label>:5:                                      ; preds = %1, %3
   %6 = phi i8* [ %4, %3 ], [ %0, %1 ]
   ret i8* %6
 }
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f2(i8* readnone %0) local_unnamed_addr #0 {
 ; FIXME: Until we have "on-demand" attribute generation we do not determine the
 ;        alignment for the return value here.
 ;             define internal nonnull align 8 i8* @f2(i8* nonnull readnone align 8 %0)
-; ATTRIBUTOR: define internal i8* @f2(i8* nonnull readnone align 8 %0)
+; ATTRIBUTOR: define internal i8* @f2(i8* nonnull readnone align 8 dereferenceable(1) %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %5, label %3
 
 ; <label>:3:                                      ; preds = %1
 
-; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 8 %0)
+; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 8 dereferenceable(1) %0)
   %4 = tail call i8* @f1(i8* nonnull %0)
   br label %7
 
 ; <label>:5:                                      ; preds = %1
-; ATTRIBUTOR: %6 = tail call i8* @f3(i8* nonnull align 16 @a2)
+; ATTRIBUTOR: %6 = tail call i8* @f3(i8* nonnull align 16 dereferenceable(1) @a2)
   %6 = tail call i8* @f3(i8* nonnull @a2)
   br label %7
 
 ; <label>:7:                                      ; preds = %5, %3
   %8 = phi i8* [ %4, %3 ], [ %6, %5 ]
   ret i8* %8
 }
 
 ; Function Attrs: nounwind readnone ssp uwtable
 define internal i8* @f3(i8* readnone %0) local_unnamed_addr #0 {
 ; FIXME: Until we have "on-demand" attribute generation we do not determine the
 ;        alignment for the return value here.
 ;             define internal nonnull align 8 i8* @f3(i8* nonnull readnone align 16 %0)
-; ATTRIBUTOR: define internal i8* @f3(i8* nonnull readnone align 16 %0)
+; ATTRIBUTOR: define internal i8* @f3(i8* nonnull readnone align 16 dereferenceable(1) %0)
   %2 = icmp eq i8* %0, null
   br i1 %2, label %3, label %5
 
 ; <label>:3:                                      ; preds = %1
-; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 16 @a2)
+; ATTRIBUTOR: %4 = tail call i8* @f1(i8* nonnull align 16 dereferenceable(1) @a2)
   %4 = tail call i8* @f1(i8* nonnull @a2)
   br label %5
 
 ; <label>:5:                                      ; preds = %1, %3
   %6 = phi i8* [ %4, %3 ], [ @a1, %1 ]
   ret i8* %6
 }
 

llvm/test/Transforms/FunctionAttrs/dereferenceable.ll

; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test2(i32* dereferenceable_or_null(4) %0, double* nonnull dereferenceable(8) %1, i1 zeroext %2)
   %5 = select i1 %2, i32* %0, i32* %4
   ret i32* %5
 }
 
 ; TEST 3
 ; GEP inbounds
 define i32* @test3_1(i32* dereferenceable(8) %0) local_unnamed_addr {
 ;             define nonnull dereferenceable(4) i32* @test3_1(i32* nonnull dereferenceable(8) %0)
-; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test3_1(i32* nonnull dereferenceable(8) %0)
+; ATTRIBUTOR: define i32* @test3_1(i32* nonnull dereferenceable(8) %0)
   %ret = getelementptr inbounds i32, i32* %0, i64 1
   ret i32* %ret
 }
 
 define i32* @test3_2(i32* dereferenceable_or_null(32) %0) local_unnamed_addr {
 ; FIXME: Argument should be mark dereferenceable because of GEP `inbounds`.
 ;             define nonnull dereferenceable(16) i32* @test3_2(i32* dereferenceable_or_null(32) %0)
-; ATTRIBUTOR: define dereferenceable_or_null(16) i32* @test3_2(i32* dereferenceable_or_null(32) %0)
+; ATTRIBUTOR: define i32* @test3_2(i32* dereferenceable_or_null(32) %0)
   %ret = getelementptr inbounds i32, i32* %0, i64 4
   ret i32* %ret
 }
 
 define i32* @test3_3(i32* dereferenceable(8) %0, i32* dereferenceable(16) %1, i1 %2) local_unnamed_addr {
 ;             define nonnull dereferenceable(4) i32* @test3_3(i32* nonnull dereferenceable(8) %0, i32* nonnull dereferenceable(16) %1, i1 %2) local_unnamed_addr
-; ATTRIBUTOR: define dereferenceable_or_null(4) i32* @test3_3(i32* nonnull dereferenceable(8) %0, i32* nonnull dereferenceable(16) %1, i1 %2) local_unnamed_addr
+; ATTRIBUTOR: define i32* @test3_3(i32* nonnull dereferenceable(8) %0, i32* nonnull dereferenceable(16) %1, i1 %2) local_unnamed_addr
   %ret1 = getelementptr inbounds i32, i32* %0, i64 1
   %ret2 = getelementptr inbounds i32, i32* %1, i64 2
   %ret = select i1 %2, i32* %ret1, i32* %ret2
   ret i32* %ret
 }
 
 ; TEST 4
 ; Better than known in IR.
 
 define dereferenceable(4) i32* @test4(i32* dereferenceable(8) %0) local_unnamed_addr {
 ; ATTRIBUTOR: define nonnull dereferenceable(8) i32* @test4(i32* nonnull returned dereferenceable(8) %0)
   ret i32* %0
 }
 

llvm/test/Transforms/FunctionAttrs/noalias_returned.ll

 declare i8* @baz(...) nounwind uwtable
 
 ; TEST 5
 
 ; Returning global pointer. Should not be noalias.
 ; FIXME: Until we have "on-demand" attribute generation we do not determine the
 ;        alignment for the return value here.
 ;        define nonnull align 8 dereferenceable(8) i8** @getter()
-; CHECK: define dereferenceable_or_null(8) i8** @getter()
+; CHECK: define i8** @getter()
 define i8** @getter() {
   ret i8** @G
 }
 
 ; FIXME: Until we have "on-demand" attribute generation we do not determine the
 ;        alignment for the return value here.
 ; Returning global pointer. Should not be noalias.
 ;        define nonnull align 8 dereferenceable(8) i8** @calle1()
-; CHECK: define dereferenceable_or_null(8) i8** @calle1()
+; CHECK: define i8** @calle1()
 define i8** @calle1(){
   %1 = call i8** @getter()
   ret i8** %1
 }
 
 ; TEST 6
 declare noalias i8* @strdup(i8* nocapture) nounwind