[PCH] Support writing BuiltinBitCastExprs to PCHs

[hyd-dev]

Summary

D62825 adds the new BuiltinBitCastExpr, but does not set the Code member of ASTStmtWriter. This is not correct and causes an assertion failue (assert(Code != serialization::STMT_NULL_PTR && "unhandled sub-statement writing AST file")) in ASTStmtWriter::emit() when building PCHs that contain __builtin_bit_cast. This patch adds serialization::EXPR_BUILTIN_BIT_CAST and handles ASTStmtWriter::Code properly.

[hyd-dev]

Format builtin-bit-cast.cpp and make it simpler.

[hyd-dev]

Ping?

[erik.pilkington]

LGTM (after a minor comment), thank you for fixing this!

clang/lib/Serialization/ASTReaderStmt.cpp

3598

PathSize should always be zero, so I think it makes more sense to assert(Record[ASTStmtReader::NumExprFields] == 0); here and remove the PathSize parameter from the BuiltinBitCastExpr constructor.

[hyd-dev]

Address the comment: remove PathSize from BuiltinBitCastExpr's constructor and assert() it == 0.

[hyd-dev]

If this is OK, please commit it with --author "hyd-dev <[e-mail]>". Thanks.

clang/include/clang/AST/ExprCXX.h

 
 public:
   BuiltinBitCastExpr(QualType T, ExprValueKind VK, CastKind CK, Expr *SrcExpr,
                      TypeSourceInfo *DstType, SourceLocation KWLoc,
                      SourceLocation RParenLoc)
       : ExplicitCastExpr(BuiltinBitCastExprClass, T, VK, CK, SrcExpr, 0,
                          DstType),
         KWLoc(KWLoc), RParenLoc(RParenLoc) {}
+  BuiltinBitCastExpr(EmptyShell Empty, unsigned PathSize)
+      : ExplicitCastExpr(BuiltinBitCastExprClass, Empty, PathSize) {}
 
   SourceLocation getBeginLoc() const LLVM_READONLY { return KWLoc; }
   SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
 
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == BuiltinBitCastExprClass;
   }
 };
 
 } // namespace clang
 
 #endif // LLVM_CLANG_AST_EXPRCXX_H

clang/include/clang/Serialization/ASTBitCodes.h

enum StmtCode {
       EXPR_CXX_REINTERPRET_CAST,
 
       /// A CXXConstCastExpr record.
       EXPR_CXX_CONST_CAST,
 
       /// A CXXFunctionalCastExpr record.
       EXPR_CXX_FUNCTIONAL_CAST,
 
+      /// A BuiltinBitCastExpr record.
+      EXPR_BUILTIN_BIT_CAST,
+
       /// A UserDefinedLiteral record.
       EXPR_USER_DEFINED_LITERAL,
 
       /// A CXXStdInitializerListExpr record.
       EXPR_CXX_STD_INITIALIZER_LIST,
 
       /// A CXXBoolLiteralExpr record.
       EXPR_CXX_BOOL_LITERAL,
 
       EXPR_CXX_NULL_PTR_LITERAL,  // CXXNullPtrLiteralExpr
       EXPR_CXX_TYPEID_EXPR,       // CXXTypeidExpr (of expr).
       EXPR_CXX_TYPEID_TYPE,       // CXXTypeidExpr (of type).
       EXPR_CXX_THIS,              // CXXThisExpr
       EXPR_CXX_THROW,             // CXXThrowExpr
       EXPR_CXX_DEFAULT_ARG,       // CXXDefaultArgExpr
       EXPR_CXX_DEFAULT_INIT,      // CXXDefaultInitExpr
       EXPR_CXX_BIND_TEMPORARY,    // CXXBindTemporaryExpr
 
       EXPR_CXX_SCALAR_VALUE_INIT, // CXXScalarValueInitExpr
       EXPR_CXX_NEW,               // CXXNewExpr
       EXPR_CXX_DELETE,            // CXXDeleteExpr
       EXPR_CXX_PSEUDO_DESTRUCTOR, // CXXPseudoDestructorExpr
 
       EXPR_EXPR_WITH_CLEANUPS,    // ExprWithCleanups
 
       EXPR_CXX_DEPENDENT_SCOPE_MEMBER,   // CXXDependentScopeMemberExpr
       EXPR_CXX_DEPENDENT_SCOPE_DECL_REF, // DependentScopeDeclRefExpr
       EXPR_CXX_UNRESOLVED_CONSTRUCT,     // CXXUnresolvedConstructExpr
       EXPR_CXX_UNRESOLVED_MEMBER,        // UnresolvedMemberExpr
       EXPR_CXX_UNRESOLVED_LOOKUP,        // UnresolvedLookupExpr
 
       EXPR_CXX_EXPRESSION_TRAIT,  // ExpressionTraitExpr
       EXPR_CXX_NOEXCEPT,          // CXXNoexceptExpr
 
       EXPR_OPAQUE_VALUE,          // OpaqueValueExpr
       EXPR_BINARY_CONDITIONAL_OPERATOR,  // BinaryConditionalOperator
       EXPR_TYPE_TRAIT,            // TypeTraitExpr
       EXPR_ARRAY_TYPE_TRAIT,      // ArrayTypeTraitIntExpr
 
       EXPR_PACK_EXPANSION,        // PackExpansionExpr
       EXPR_SIZEOF_PACK,           // SizeOfPackExpr
       EXPR_SUBST_NON_TYPE_TEMPLATE_PARM, // SubstNonTypeTemplateParmExpr
       EXPR_SUBST_NON_TYPE_TEMPLATE_PARM_PACK,// SubstNonTypeTemplateParmPackExpr
       EXPR_FUNCTION_PARM_PACK,    // FunctionParmPackExpr
       EXPR_MATERIALIZE_TEMPORARY, // MaterializeTemporaryExpr
       EXPR_CXX_FOLD,              // CXXFoldExpr
       EXPR_CONCEPT_SPECIALIZATION,// ConceptSpecializationExpr
       EXPR_REQUIRES,              // RequiresExpr
 
       // CUDA
       EXPR_CUDA_KERNEL_CALL,       // CUDAKernelCallExpr
 
       // OpenCL
       EXPR_ASTYPE,                 // AsTypeExpr
 
       // Microsoft
       EXPR_CXX_PROPERTY_REF_EXPR, // MSPropertyRefExpr
       EXPR_CXX_PROPERTY_SUBSCRIPT_EXPR, // MSPropertySubscriptExpr
       EXPR_CXX_UUIDOF_EXPR,       // CXXUuidofExpr (of expr).
       EXPR_CXX_UUIDOF_TYPE,       // CXXUuidofExpr (of type).
       STMT_SEH_LEAVE,             // SEHLeaveStmt
       STMT_SEH_EXCEPT,            // SEHExceptStmt
       STMT_SEH_FINALLY,           // SEHFinallyStmt
       STMT_SEH_TRY,               // SEHTryStmt
 
       // OpenMP directives
       STMT_OMP_PARALLEL_DIRECTIVE,
       STMT_OMP_SIMD_DIRECTIVE,
       STMT_OMP_FOR_DIRECTIVE,
       STMT_OMP_FOR_SIMD_DIRECTIVE,
       STMT_OMP_SECTIONS_DIRECTIVE,
       STMT_OMP_SECTION_DIRECTIVE,
       STMT_OMP_SINGLE_DIRECTIVE,
enum StmtCode {
 
       // ARC
       EXPR_OBJC_BRIDGED_CAST,     // ObjCBridgedCastExpr
 
       STMT_MS_DEPENDENT_EXISTS,   // MSDependentExistsStmt
       EXPR_LAMBDA,                // LambdaExpr
       STMT_COROUTINE_BODY,
       STMT_CORETURN,
       EXPR_COAWAIT,
       EXPR_COYIELD,
       EXPR_DEPENDENT_COAWAIT,
 
       // FixedPointLiteral
       EXPR_FIXEDPOINT_LITERAL,
     };
 
     /// The kinds of designators that can occur in a
     /// DesignatedInitExpr.
     enum DesignatorTypes {

clang/lib/Serialization/ASTReaderStmt.cpp

case EXPR_CXX_CONST_CAST:
       S = CXXConstCastExpr::CreateEmpty(Context);
       break;
 
     case EXPR_CXX_FUNCTIONAL_CAST:
       S = CXXFunctionalCastExpr::CreateEmpty(Context,
                        /*PathSize*/ Record[ASTStmtReader::NumExprFields]);
       break;
 
+    case EXPR_BUILTIN_BIT_CAST:
+      S = new (Context) BuiltinBitCastExpr(
+          Empty, /*PathSize*/ Record[ASTStmtReader::NumExprFields]);
+      break;
+
     case EXPR_USER_DEFINED_LITERAL:
       S = UserDefinedLiteral::CreateEmpty(
           Context, /*NumArgs=*/Record[ASTStmtReader::NumExprFields], Empty);
       break;
 
     case EXPR_CXX_STD_INITIALIZER_LIST:
       S = new (Context) CXXStdInitializerListExpr(Empty);
       break;

clang/lib/Serialization/ASTWriterStmt.cpp

void ASTStmtWriter::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E) {
   Record.AddSourceLocation(E->getRParenLoc());
   Code = serialization::EXPR_CXX_FUNCTIONAL_CAST;
 }
 
 void ASTStmtWriter::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *E) {
   VisitExplicitCastExpr(E);
   Record.AddSourceLocation(E->getBeginLoc());
   Record.AddSourceLocation(E->getEndLoc());
+  Code = serialization::EXPR_BUILTIN_BIT_CAST;
 }
 
 void ASTStmtWriter::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
   VisitCallExpr(E);
   Record.AddSourceLocation(E->UDSuffixLoc);
   Code = serialization::EXPR_USER_DEFINED_LITERAL;
 }
 

clang/test/PCH/builtin-bit-cast.cpp

+// RUN: %clang_cc1 -emit-pch -o %t %s
+// RUN: %clang_cc1 -include-pch %t -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+template<class T, class U>
+constexpr T builtin_bit_cast_wrapper(const U& arg) {
+  return __builtin_bit_cast(T, arg);
+}
+
+#else
+
+int main() {
+  builtin_bit_cast_wrapper<int>(0);
+  return 0;
+}
+
+#endif