Introduce the AttributeMask class

This class is solely used as a lightweight and clean way to build a set of
attributes to be removed from an AttrBuilder. Previously AttrBuilder was used
both for building and removing, which introduced odd situation like creation of
Attribute with dummy value because the only relevant part was the attribute
kind.

Differential Revision: https://reviews.llvm.org/D116110

Author: serge-sans-paille

clang/lib/CodeGen/CodeGenModule.cpp

@@ -2097,7 +2097,7 @@ void CodeGenModule::setNonAliasAttributes(GlobalDecl GD,
         // We know that GetCPUAndFeaturesAttributes will always have the
         // newest set, since it has the newest possible FunctionDecl, so the
         // new ones should replace the old.
-        llvm::AttrBuilder RemoveAttrs;
+        llvm::AttributeMask RemoveAttrs;
         RemoveAttrs.addAttribute("target-cpu");
         RemoveAttrs.addAttribute("target-features");
         RemoveAttrs.addAttribute("tune-cpu");

llvm/include/llvm/IR/Argument.h

@@ -162,7 +162,7 @@ class Argument final : public Value {
   /// Remove attributes from an argument.
   void removeAttr(Attribute::AttrKind Kind);
 
-  void removeAttrs(const AttrBuilder &B);
+  void removeAttrs(const AttributeMask &AM);
 
   /// Check if an argument has a given attribute.
   bool hasAttribute(Attribute::AttrKind Kind) const;

llvm/include/llvm/IR/Attributes.h

@@ -28,12 +28,14 @@
 #include <cassert>
 #include <cstdint>
 #include <map>
+#include <set>
 #include <string>
 #include <utility>
 
 namespace llvm {
 
 class AttrBuilder;
+class AttributeMask;
 class AttributeImpl;
 class AttributeListImpl;
 class AttributeSetNode;
@@ -320,7 +322,7 @@ class AttributeSet {
   /// Remove the specified attributes from this set. Returns a new set because
   /// attribute sets are immutable.
   LLVM_NODISCARD AttributeSet
-  removeAttributes(LLVMContext &C, const AttrBuilder &AttrsToRemove) const;
+  removeAttributes(LLVMContext &C, const AttributeMask &AttrsToRemove) const;
 
   /// Return the number of attributes in this set.
   unsigned getNumAttributes() const;
@@ -580,7 +582,7 @@ class AttributeList {
   /// Remove the specified attributes at the specified index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
   LLVM_NODISCARD AttributeList removeAttributesAtIndex(
-      LLVMContext &C, unsigned Index, const AttrBuilder &AttrsToRemove) const;
+      LLVMContext &C, unsigned Index, const AttributeMask &AttrsToRemove) const;
 
   /// Remove all attributes at the specified index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
@@ -604,7 +606,7 @@ class AttributeList {
   /// Remove the specified attribute at the function index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
   LLVM_NODISCARD AttributeList
-  removeFnAttributes(LLVMContext &C, const AttrBuilder &AttrsToRemove) const {
+  removeFnAttributes(LLVMContext &C, const AttributeMask &AttrsToRemove) const {
     return removeAttributesAtIndex(C, FunctionIndex, AttrsToRemove);
   }
 
@@ -630,8 +632,8 @@ class AttributeList {
 
   /// Remove the specified attribute at the return value index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
-  LLVM_NODISCARD AttributeList
-  removeRetAttributes(LLVMContext &C, const AttrBuilder &AttrsToRemove) const {
+  LLVM_NODISCARD AttributeList removeRetAttributes(
+      LLVMContext &C, const AttributeMask &AttrsToRemove) const {
     return removeAttributesAtIndex(C, ReturnIndex, AttrsToRemove);
   }
 
@@ -652,8 +654,9 @@ class AttributeList {
 
   /// Remove the specified attribute at the specified arg index from this
   /// attribute list. Returns a new list because attribute lists are immutable.
-  LLVM_NODISCARD AttributeList removeParamAttributes(
-      LLVMContext &C, unsigned ArgNo, const AttrBuilder &AttrsToRemove) const {
+  LLVM_NODISCARD AttributeList
+  removeParamAttributes(LLVMContext &C, unsigned ArgNo,
+                        const AttributeMask &AttrsToRemove) const {
     return removeAttributesAtIndex(C, ArgNo + FirstArgIndex, AttrsToRemove);
   }
 
@@ -927,6 +930,65 @@ template <> struct DenseMapInfo<AttributeList, void> {
   }
 };
 
+//===----------------------------------------------------------------------===//
+/// \class
+/// This class stores enough information to efficiently remove some attributes
+/// from an existing AttrBuilder, AttributeSet or AttributeList.
+class AttributeMask {
+  std::bitset<Attribute::EndAttrKinds> Attrs;
+  std::set<SmallString<32>, std::less<>> TargetDepAttrs;
+
+public:
+  AttributeMask() = default;
+  AttributeMask(const AttributeMask &) = delete;
+  AttributeMask(AttributeMask &&) = default;
+
+  AttributeMask(AttributeSet AS) {
+    for (Attribute A : AS)
+      addAttribute(A);
+  }
+
+  /// Add an attribute to the mask.
+  AttributeMask &addAttribute(Attribute::AttrKind Val) {
+    assert((unsigned)Val < Attribute::EndAttrKinds &&
+           "Attribute out of range!");
+    Attrs[Val] = true;
+    return *this;
+  }
+
+  /// Add the Attribute object to the builder.
+  AttributeMask &addAttribute(Attribute A) {
+    if (A.isStringAttribute())
+      addAttribute(A.getKindAsString());
+    else
+      addAttribute(A.getKindAsEnum());
+    return *this;
+  }
+
+  /// Add the target-dependent attribute to the builder.
+  AttributeMask &addAttribute(StringRef A) {
+    TargetDepAttrs.insert(A);
+    return *this;
+  }
+
+  /// Return true if the builder has the specified attribute.
+  bool contains(Attribute::AttrKind A) const {
+    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
+    return Attrs[A];
+  }
+
+  /// Return true if the builder has the specified target-dependent
+  /// attribute.
+  bool contains(StringRef A) const { return TargetDepAttrs.count(A); }
+
+  using td_const_iterator = decltype(TargetDepAttrs)::const_iterator;
+  using td_const_range = iterator_range<td_const_iterator>;
+  td_const_range td_attrs() const {
+    return {TargetDepAttrs.begin(), TargetDepAttrs.end()};
+  }
+  auto const &attrs() const { return Attrs; }
+};
+
 //===----------------------------------------------------------------------===//
 /// \class
 /// This class is used in conjunction with the Attribute::get method to
@@ -975,21 +1037,29 @@ class AttrBuilder {
   /// Remove an attribute from the builder.
   AttrBuilder &removeAttribute(Attribute::AttrKind Val);
 
+  /// Remove the target-dependent attribute from the builder.
+  AttrBuilder &removeAttribute(StringRef A);
+
+  /// Remove the target-dependent attribute from the builder.
+  AttrBuilder &removeAttribute(Attribute A) {
+    if (A.isStringAttribute())
+      return removeAttribute(A.getKindAsString());
+    else
+      return removeAttribute(A.getKindAsEnum());
+  }
+
   /// Remove the attributes from the builder.
   AttrBuilder &removeAttributes(AttributeList A, uint64_t WithoutIndex);
 
-  /// Remove the target-dependent attribute to the builder.
-  AttrBuilder &removeAttribute(StringRef A);
-
   /// Add the attributes from the builder.
   AttrBuilder &merge(const AttrBuilder &B);
 
   /// Remove the attributes from the builder.
-  AttrBuilder &remove(const AttrBuilder &B);
+  AttrBuilder &remove(const AttributeMask &AM);
 
   /// Return true if the builder has any attribute that's in the
   /// specified builder.
-  bool overlaps(const AttrBuilder &B) const;
+  bool overlaps(const AttributeMask &AM) const;
 
   /// Return true if the builder has the specified attribute.
   bool contains(Attribute::AttrKind A) const {
@@ -1168,14 +1238,14 @@ class AttrBuilder {
 namespace AttributeFuncs {
 
 /// Which attributes cannot be applied to a type.
-AttrBuilder typeIncompatible(Type *Ty);
+AttributeMask typeIncompatible(Type *Ty);
 
 /// Get param/return attributes which imply immediate undefined behavior if an
 /// invalid value is passed. For example, this includes noundef (where undef
 /// implies UB), but not nonnull (where null implies poison). It also does not
 /// include attributes like nocapture, which constrain the function
 /// implementation rather than the passed value.
-AttrBuilder getUBImplyingAttributes();
+AttributeMask getUBImplyingAttributes();
 
 /// \returns Return true if the two functions have compatible target-independent
 /// attributes for inlining purposes.

llvm/include/llvm/IR/Function.h

@@ -364,7 +364,7 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
   /// Remove function attribute from this function.
   void removeFnAttr(StringRef Kind);
 
-  void removeFnAttrs(const AttrBuilder &Attrs);
+  void removeFnAttrs(const AttributeMask &Attrs);
 
   /// removes the attribute from the return value list of attributes.
   void removeRetAttr(Attribute::AttrKind Kind);
@@ -373,7 +373,7 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
   void removeRetAttr(StringRef Kind);
 
   /// removes the attributes from the return value list of attributes.
-  void removeRetAttrs(const AttrBuilder &Attrs);
+  void removeRetAttrs(const AttributeMask &Attrs);
 
   /// removes the attribute from the list of attributes.
   void removeParamAttr(unsigned ArgNo, Attribute::AttrKind Kind);
@@ -382,7 +382,7 @@ class LLVM_EXTERNAL_VISIBILITY Function : public GlobalObject,
   void removeParamAttr(unsigned ArgNo, StringRef Kind);
 
   /// removes the attribute from the list of attributes.
-  void removeParamAttrs(unsigned ArgNo, const AttrBuilder &Attrs);
+  void removeParamAttrs(unsigned ArgNo, const AttributeMask &Attrs);
 
   /// Return true if the function has the attribute.
   bool hasFnAttribute(Attribute::AttrKind Kind) const;

llvm/include/llvm/IR/InstrTypes.h

@@ -1544,7 +1544,7 @@ class CallBase : public Instruction {
   }
 
   /// Removes the attributes from the function
-  void removeFnAttrs(const AttrBuilder &AttrsToRemove) {
+  void removeFnAttrs(const AttributeMask &AttrsToRemove) {
     Attrs = Attrs.removeFnAttributes(getContext(), AttrsToRemove);
   }
 
@@ -1559,7 +1559,7 @@ class CallBase : public Instruction {
   }
 
   /// Removes the attributes from the return value
-  void removeRetAttrs(const AttrBuilder &AttrsToRemove) {
+  void removeRetAttrs(const AttributeMask &AttrsToRemove) {
     Attrs = Attrs.removeRetAttributes(getContext(), AttrsToRemove);
   }
 
@@ -1576,7 +1576,7 @@ class CallBase : public Instruction {
   }
 
   /// Removes the attributes from the given argument
-  void removeParamAttrs(unsigned ArgNo, const AttrBuilder &AttrsToRemove) {
+  void removeParamAttrs(unsigned ArgNo, const AttributeMask &AttrsToRemove) {
     Attrs = Attrs.removeParamAttributes(getContext(), ArgNo, AttrsToRemove);
   }