[AST] Use APIntStorage to fix memory leak in EnumConstantDecl.

clang/docs/ReleaseNotes.rst

@@ -675,6 +675,8 @@ Bug Fixes in This Version
   Fixes (`#67317 <https://github.com/llvm/llvm-project/issues/67317>`_)
 - Clang now properly diagnoses use of stand-alone OpenMP directives after a
   label (including ``case`` or ``default`` labels).
+- Fix compiler memory leak for enums with underlying type larger than 64 bits.
+  Fixes (`#78311 <https://github.com/llvm/llvm-project/pull/78311>`_)
 
   Before:
 

clang/include/clang/AST/APNumericStorage.h

@@ -0,0 +1,71 @@
+//===--- APNumericStorage.h - Store APInt/APFloat in ASTContext -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_APNUMERICSTORAGE_H
+#define LLVM_CLANG_AST_APNUMERICSTORAGE_H
+
+#include "llvm/ADT/APFloat.h"
+#include "llvm/ADT/APInt.h"
+
+namespace clang {
+class ASTContext;
+
+/// Used by IntegerLiteral/FloatingLiteral/EnumConstantDecl to store the
+/// numeric without leaking memory.
+///
+/// For large floats/integers, APFloat/APInt will allocate memory from the heap
+/// to represent these numbers.  Unfortunately, when we use a BumpPtrAllocator
+/// to allocate IntegerLiteral/FloatingLiteral nodes the memory associated with
+/// the APFloat/APInt values will never get freed. APNumericStorage uses
+/// ASTContext's allocator for memory allocation.
+class APNumericStorage {
+  union {
+    uint64_t VAL;   ///< Used to store the <= 64 bits integer value.
+    uint64_t *pVal; ///< Used to store the >64 bits integer value.
+  };
+  unsigned BitWidth;
+
+  bool hasAllocation() const { return llvm::APInt::getNumWords(BitWidth) > 1; }
+
+  APNumericStorage(const APNumericStorage &) = delete;
+  void operator=(const APNumericStorage &) = delete;
+
+protected:
+  APNumericStorage() : VAL(0), BitWidth(0) {}
+
+  llvm::APInt getIntValue() const {
+    unsigned NumWords = llvm::APInt::getNumWords(BitWidth);
+    if (NumWords > 1)
+      return llvm::APInt(BitWidth, NumWords, pVal);
+    else
+      return llvm::APInt(BitWidth, VAL);
+  }
+  void setIntValue(const ASTContext &C, const llvm::APInt &Val);
+};
+
+class APIntStorage : private APNumericStorage {
+public:
+  llvm::APInt getValue() const { return getIntValue(); }
+  void setValue(const ASTContext &C, const llvm::APInt &Val) {
+    setIntValue(C, Val);
+  }
+};
+
+class APFloatStorage : private APNumericStorage {
+public:
+  llvm::APFloat getValue(const llvm::fltSemantics &Semantics) const {
+    return llvm::APFloat(Semantics, getIntValue());
+  }
+  void setValue(const ASTContext &C, const llvm::APFloat &Val) {
+    setIntValue(C, Val.bitcastToAPInt());
+  }
+};
+
+} // end namespace clang
+
+#endif // LLVM_CLANG_AST_APNUMERICSTORAGE_H

clang/include/clang/AST/Decl.h

@@ -13,6 +13,7 @@
 #ifndef LLVM_CLANG_AST_DECL_H
 #define LLVM_CLANG_AST_DECL_H
 
+#include "clang/AST/APNumericStorage.h"
 #include "clang/AST/APValue.h"
 #include "clang/AST/ASTContextAllocate.h"
 #include "clang/AST/DeclAccessPair.h"
@@ -3251,15 +3252,16 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
 /// that is defined.  For example, in "enum X {a,b}", each of a/b are
 /// EnumConstantDecl's, X is an instance of EnumDecl, and the type of a/b is a
 /// TagType for the X EnumDecl.
-class EnumConstantDecl : public ValueDecl, public Mergeable<EnumConstantDecl> {
+class EnumConstantDecl : public ValueDecl,
+                         public Mergeable<EnumConstantDecl>,
+                         public APIntStorage {
   Stmt *Init; // an integer constant expression
-  llvm::APSInt Val; // The value.
+  bool IsUnsigned;
 
 protected:
-  EnumConstantDecl(DeclContext *DC, SourceLocation L,
+  EnumConstantDecl(const ASTContext &C, DeclContext *DC, SourceLocation L,
                    IdentifierInfo *Id, QualType T, Expr *E,
-                   const llvm::APSInt &V)
-    : ValueDecl(EnumConstant, DC, L, Id, T), Init((Stmt*)E), Val(V) {}
+                   const llvm::APSInt &V);
 
 public:
   friend class StmtIteratorBase;
@@ -3272,10 +3274,15 @@ class EnumConstantDecl : public ValueDecl, public Mergeable<EnumConstantDecl> {
 
   const Expr *getInitExpr() const { return (const Expr*) Init; }
   Expr *getInitExpr() { return (Expr*) Init; }
-  const llvm::APSInt &getInitVal() const { return Val; }
+  llvm::APSInt getInitVal() const {
+    return llvm::APSInt(getValue(), IsUnsigned);
+  }
 
   void setInitExpr(Expr *E) { Init = (Stmt*) E; }
-  void setInitVal(const llvm::APSInt &V) { Val = V; }
+  void setInitVal(const ASTContext &C, const llvm::APSInt &V) {
+    setValue(C, V);
+    IsUnsigned = V.isUnsigned();
+  }
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 

clang/include/clang/AST/Expr.h

@@ -13,6 +13,7 @@
 #ifndef LLVM_CLANG_AST_EXPR_H
 #define LLVM_CLANG_AST_EXPR_H
 
+#include "clang/AST/APNumericStorage.h"
 #include "clang/AST/APValue.h"
 #include "clang/AST/ASTVector.h"
 #include "clang/AST/ComputeDependence.h"
@@ -1479,57 +1480,6 @@ class DeclRefExpr final
   }
 };
 
-/// Used by IntegerLiteral/FloatingLiteral to store the numeric without
-/// leaking memory.
-///
-/// For large floats/integers, APFloat/APInt will allocate memory from the heap
-/// to represent these numbers.  Unfortunately, when we use a BumpPtrAllocator
-/// to allocate IntegerLiteral/FloatingLiteral nodes the memory associated with
-/// the APFloat/APInt values will never get freed. APNumericStorage uses
-/// ASTContext's allocator for memory allocation.
-class APNumericStorage {
-  union {
-    uint64_t VAL;    ///< Used to store the <= 64 bits integer value.
-    uint64_t *pVal;  ///< Used to store the >64 bits integer value.
-  };
-  unsigned BitWidth;
-
-  bool hasAllocation() const { return llvm::APInt::getNumWords(BitWidth) > 1; }
-
-  APNumericStorage(const APNumericStorage &) = delete;
-  void operator=(const APNumericStorage &) = delete;
-
-protected:
-  APNumericStorage() : VAL(0), BitWidth(0) { }
-
-  llvm::APInt getIntValue() const {
-    unsigned NumWords = llvm::APInt::getNumWords(BitWidth);
-    if (NumWords > 1)
-      return llvm::APInt(BitWidth, NumWords, pVal);
-    else
-      return llvm::APInt(BitWidth, VAL);
-  }
-  void setIntValue(const ASTContext &C, const llvm::APInt &Val);
-};
-
-class APIntStorage : private APNumericStorage {
-public:
-  llvm::APInt getValue() const { return getIntValue(); }
-  void setValue(const ASTContext &C, const llvm::APInt &Val) {
-    setIntValue(C, Val);
-  }
-};
-
-class APFloatStorage : private APNumericStorage {
-public:
-  llvm::APFloat getValue(const llvm::fltSemantics &Semantics) const {
-    return llvm::APFloat(Semantics, getIntValue());
-  }
-  void setValue(const ASTContext &C, const llvm::APFloat &Val) {
-    setIntValue(C, Val.bitcastToAPInt());
-  }
-};
-
 class IntegerLiteral : public Expr, public APIntStorage {
   SourceLocation Loc;
 

clang/lib/AST/Decl.cpp

@@ -5369,16 +5369,23 @@ void CapturedDecl::setBody(Stmt *B) { BodyAndNothrow.setPointer(B); }
 bool CapturedDecl::isNothrow() const { return BodyAndNothrow.getInt(); }
 void CapturedDecl::setNothrow(bool Nothrow) { BodyAndNothrow.setInt(Nothrow); }
 
+EnumConstantDecl::EnumConstantDecl(const ASTContext &C, DeclContext *DC,
+                                   SourceLocation L, IdentifierInfo *Id,
+                                   QualType T, Expr *E, const llvm::APSInt &V)
+    : ValueDecl(EnumConstant, DC, L, Id, T), Init((Stmt *)E) {
+  setInitVal(C, V);
+}
+
 EnumConstantDecl *EnumConstantDecl::Create(ASTContext &C, EnumDecl *CD,
                                            SourceLocation L,
                                            IdentifierInfo *Id, QualType T,
                                            Expr *E, const llvm::APSInt &V) {
-  return new (C, CD) EnumConstantDecl(CD, L, Id, T, E, V);
+  return new (C, CD) EnumConstantDecl(C, CD, L, Id, T, E, V);
 }
 
 EnumConstantDecl *
 EnumConstantDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
-  return new (C, ID) EnumConstantDecl(nullptr, SourceLocation(), nullptr,
+  return new (C, ID) EnumConstantDecl(C, nullptr, SourceLocation(), nullptr,
                                       QualType(), nullptr, llvm::APSInt());
 }
 

clang/lib/CodeGen/CGBuiltin.cpp

@@ -13047,7 +13047,7 @@ Value *CodeGenFunction::EmitBPFBuiltinExpr(unsigned BuiltinID,
     const auto *DR = cast<DeclRefExpr>(CE->getSubExpr());
     const auto *Enumerator = cast<EnumConstantDecl>(DR->getDecl());
 
-    auto &InitVal = Enumerator->getInitVal();
+    auto InitVal = Enumerator->getInitVal();
     std::string InitValStr;
     if (InitVal.isNegative() || InitVal > uint64_t(INT64_MAX))
       InitValStr = std::to_string(InitVal.getSExtValue());

clang/lib/Sema/SemaDecl.cpp

@@ -20214,7 +20214,7 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
     // Adjust the APSInt value.
     InitVal = InitVal.extOrTrunc(NewWidth);
     InitVal.setIsSigned(NewSign);
-    ECD->setInitVal(InitVal);
+    ECD->setInitVal(Context, InitVal);
 
     // Adjust the Expr initializer and type.
     if (ECD->getInitExpr() &&

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -910,7 +910,7 @@ void ASTDeclReader::VisitEnumConstantDecl(EnumConstantDecl *ECD) {
   VisitValueDecl(ECD);
   if (Record.readInt())
     ECD->setInitExpr(Record.readExpr());
-  ECD->setInitVal(Record.readAPSInt());
+  ECD->setInitVal(Reader.getContext(), Record.readAPSInt());
   mergeMergeable(ECD);
 }