Changeset c36298d for src/AST

Timestamp:

Jun 17, 2019, 11:01:04 AM (5 years ago)

Author:

Michael Brooks <mlbrooks@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

b4d34fa

Parents:

6a1dfda

Message:

Fixed handling of "literals.cfa" string-detail test cases by simplifying constant analysis. Now a ConstantExpr? is a minial passthrough from parser to code generator, with special-case analysis only for integer values. Awareness of how to build a string-constant type is back in ExpressionNode?.cc; now, this knowlede is only needed there. AST conversion no longer specializes string-int-float constants; it just converts types and passes values through. Unused constant API features are removed, notably from-to-float and from-string.

Location:

src/AST

Files:

• Convert.cpp (modified) (2 diffs)
• Expr.cpp (modified) (3 diffs)
• Expr.hpp (modified) (4 diffs)

src/AST/Convert.cpp

@@ -740 +740 @@
 
         const ast::Expr * visit( const ast::ConstantExpr * node ) override final {
-                ConstantExpr *rslt = nullptr;
-                switch ( node->kind ) {
-                case ast::ConstantExpr::Integer:
-                        rslt = new ConstantExpr{Constant{
-                                get<Type>().accept1( node->result ),
-                                node->rep,
-                                (unsigned long long) node->intValue()
-                        }};
-                        break;
-                case ast::ConstantExpr::FloatingPoint:
-                        rslt = new ConstantExpr{Constant{
-                                get<Type>().accept1(node->result),
-                                node->rep,
-                                (double) node->floatValue()
-                        }};
-                        break;
-                case ast::ConstantExpr::String:
-                        // Old world:   two types: rslt->constant.type, rslt->result
-                        // New workd:   one type: node->result
-                        // Both worlds: the outer, expression-level type can change during resolution
-                        //              in case of string, that's char[k] before-resolve and char * after
-                        // Old world:   the inner Constant type stays what it was built with
-                        //              in case of string, that's char[k]
-                        // Both worlds: the "rep" field of a string constant is the string value it was initialized from, wrapped in quotes, but not otherwise escaped
-                        ast::ptr<ast::Type> charType = nullptr;
-                        if (const ast::ArrayType *arrRslt = node->result.as<ast::ArrayType>()) {
-                                charType = arrRslt->base;
-                        } else {
-                                const ast::PointerType *ptrRslt = node->result.as<ast::PointerType>();
-                                assert(ptrRslt);
-                                charType = ptrRslt->base;
-                        }
-                        rslt = new ConstantExpr(Constant::from_string(
-                                node->rep, get<Type>().accept1(charType)));          // rslt->result is char[k]
-                        rslt->set_result( get<Type>().accept1( node->result ) ); // rslt->result is [[ node->rsult ]]
-                        break;
-                }
-                assert(rslt);
+                // Old world:   two types: rslt->constant.type, rslt->result
+                // New workd:   one public type: node->result, plus node->underlyer only to support roundtrip conversion
+                //              preserving underlyer because the correct type for string literals is complicated to construct,
+            //              and distinguishing a string from other literals using the type is hard to do accurately
+                // Both worlds: the outer, expression-level type can change during resolution
+                //              for a string, that's char[k] before-resolve and char * after
+                // Old world:   the inner Constant type stays what it was built with
+                //              for a string, that's char[k] always
+                // Both worlds: the "rep" field of a constant is the C source file fragment that compiles to the desired value
+        //              for a string, that includes outer quotes, backslashes, et al cases from the Literals test
+                ConstantExpr *rslt = new ConstantExpr(Constant(
+                        get<Type>().accept1(node->underlyer),
+                        node->rep,
+                        node->ival));
                 auto expr = visitBaseExpr( node, rslt );
                 this->node = expr;
@@ -2162 +2138 @@
         }
 
-        bool isIntlikeConstantType(const Type *t) {
-                if ( const BasicType * basicType = dynamic_cast< const BasicType * >( t ) ) {
-                        if ( basicType->isInteger() ) {
-                                return true;
-                        }
-                } else if ( dynamic_cast< const OneType * >( t ) ) {
-                        return true;
-                } else if ( dynamic_cast< const ZeroType * >( t ) ) {
-                        return true;
-                } else if ( dynamic_cast< const PointerType * >( t ) ) {
-                        // null pointer constants, with zero int-values
-                        return true;
-                }
-                return false;
-        }
-
-        int isFloatlikeConstantType(const Type *t) {
-                if ( const BasicType * bty = dynamic_cast< const BasicType * >( t ) ) {
-                        if ( ! bty->isInteger() ) {
-                                return true;
-                        }
-                }
-                return false;
-        }
-
-        int isStringlikeConstantType(const Type *t) {
-                const Type *referentType = nullptr;
-                if ( const ArrayType * aty = dynamic_cast< const ArrayType * >( t ) ) {
-                        referentType = aty->base;
-                } else if ( const PointerType * pty = dynamic_cast< const PointerType * >( t ) ) {
-                        referentType = pty->base;
-                }
-                if (referentType) {
-                        if ( const BasicType * bty = dynamic_cast< const BasicType * >( referentType ) ) {
-                           if ( bty->kind == BasicType::Kind::Char ) {
-                                   return true;
-                           }
-                        }
-                }
-                return false;
-        }
-
         virtual void visit( ConstantExpr * old ) override final {
-                ast::ConstantExpr *rslt = nullptr;
-                if (isStringlikeConstantType(old->result)) {
-                        rslt = new ast::ConstantExpr(
-                                old->location,
-                                GET_ACCEPT_1(result, Type), // preserve the expression-level type (old->result, not old->constant.type); see new-to-old
-                                old->constant.get_value(),
-                                0,
-                                ast::ConstantExpr::Kind::String
-                        );
-                } else if (isIntlikeConstantType(old->result)) {
-                        rslt = new ast::ConstantExpr(
-                                old->location,
-                                GET_ACCEPT_1(result, Type),
-                                old->constant.get_value(),
-                                (unsigned long long) old->intValue(),
-                                ast::ConstantExpr::Kind::Integer
-                        );
-                } else if (isFloatlikeConstantType(old->result)) {
-                        rslt = new ast::ConstantExpr(
-                                old->location,
-                                GET_ACCEPT_1(result, Type),
-                                old->constant.get_value(),
-                                (double) old->constant.get_dval()
-                        );
-                }
-                assert(rslt);
+                ast::ConstantExpr *rslt = new ast::ConstantExpr(
+                        old->location,
+                        GET_ACCEPT_1(result, Type),
+                        old->constant.get_value(),
+                        old->constant.ival
+                );
+                rslt->underlyer = getAccept1< ast::Type, Type* >( old->constant.get_type() );
                 this->node = visitBaseExpr( old, rslt );
         }

src/AST/Expr.cpp

@@ -194 +194 @@
         if ( const BasicType * bty = result.as< BasicType >() ) {
                 if ( bty->isInteger() ) {
-                        return val.ival;
+                        assert(ival);
+                        return ival.value();
                 }
         } else if ( result.as< ZeroType >() ) {
@@ -204 +205 @@
 }
 
-double ConstantExpr::floatValue() const {
-        if ( const BasicType * bty = result.as< BasicType >() ) {
-                if ( ! bty->isInteger() ) {
-                        return val.dval;
-                }
-        }
-        SemanticError( this, "Constant expression of non-floating-point type " );
-}
-
 ConstantExpr * ConstantExpr::from_bool( const CodeLocation & loc, bool b ) {
         return new ConstantExpr{
                 loc, new BasicType{ BasicType::Bool }, b ? "1" : "0", (unsigned long long)b };
-}
-
-ConstantExpr * ConstantExpr::from_char( const CodeLocation & loc, char c ) {
-        return new ConstantExpr{
-                loc, new BasicType{ BasicType::Char }, std::to_string( c ), (unsigned long long)c };
 }
 
@@ -232 +219 @@
                 loc, new BasicType{ BasicType::LongUnsignedInt }, std::to_string( i ),
                 (unsigned long long)i };
-}
-
-ConstantExpr * ConstantExpr::from_double( const CodeLocation & loc, double d ) {
-        return new ConstantExpr{ loc, new BasicType{ BasicType::Double }, std::to_string( d ), d };
 }
 

src/AST/Expr.hpp

@@ -22 +22 @@
 #include <utility>        // for move
 #include <vector>
+#include <optional>
 
 #include "Fwd.hpp"        // for UniqueId
@@ -32 +33 @@
 
 class ConverterOldToNew;
+class ConverterNewToOld;
 
 namespace ast {
@@ -346 +348 @@
 };
 
-/// A compile-time constant
+/// A compile-time constant.
+/// Mostly carries C-source text from parse to code-gen, without interpretation.  E.g. strings keep their outer quotes and never have backslashes interpreted.
+/// Integer constants get special treatment, e.g. for verifying array operations, when an integer constant occurs as the length of an array.
 class ConstantExpr final : public Expr {
-        union Val {
-                unsigned long long ival;
-                double dval;
-
-                Val( unsigned long long i ) : ival( i ) {}
-                Val( double d ) : dval( d ) {}
-        } val;
-public:
+public:
+        // Representation of this constant, as it occurs in .cfa source and .cfa.cc result.
         std::string rep;
-        enum Kind { Integer, FloatingPoint, String } kind;
 
         ConstantExpr(
-                const CodeLocation & loc, const Type * ty, const std::string & r, unsigned long long v,
-                Kind k = Integer )
-        : Expr( loc, ty ), val( v ), rep( r ), kind( k ) {}
-        ConstantExpr( const CodeLocation & loc, const Type * ty, const std::string & r, double v )
-        : Expr( loc, ty ), val( v ), rep( r ), kind( FloatingPoint ) {}
-
-        /// Gets the value of this constant as an integer
+                const CodeLocation & loc, const Type * ty, const std::string & r, 
+                        std::optional<unsigned long long> i )
+        : Expr( loc, ty ), rep( r ), ival( i ) {}
+
+        /// Gets the integer value of this constant, if one is appropriate to its type.
+        /// Throws a SemanticError if the type is not appropriate for value-as-integer.
+        /// Suffers an assertion failure the type is appropriate but no integer value was supplied to the constructor.
         long long int intValue() const;
-        /// Gets the value of this constant as floating point
-        double floatValue() const;
 
         /// generates a boolean constant of the given bool
         static ConstantExpr * from_bool( const CodeLocation & loc, bool b );
-        /// generates a char constant of the given char
-        static ConstantExpr * from_char( const CodeLocation & loc, char c );
         /// generates an integer constant of the given int
         static ConstantExpr * from_int( const CodeLocation & loc, int i );
         /// generates an integer constant of the given unsigned long int
         static ConstantExpr * from_ulong( const CodeLocation & loc, unsigned long i );
-        /// generates a floating point constant of the given double
-        static ConstantExpr * from_double( const CodeLocation & loc, double d );
         /// generates a null pointer value for the given type. void * if omitted.
         static ConstantExpr * null( const CodeLocation & loc, const Type * ptrType = nullptr );
@@ -388 +379 @@
         ConstantExpr * clone() const override { return new ConstantExpr{ *this }; }
         MUTATE_FRIEND
+
+        std::optional<unsigned long long> ival;
+
+        // Intended only for legacy support of roundtripping the old AST.
+        // Captures the very-locally inferred type, before the resolver modifies the type of this ConstantExpression.
+        // In the old AST it's constExpr->constant.type
+        ptr<Type> underlyer;
+        friend class ::ConverterOldToNew;
+        friend class ::ConverterNewToOld;
 };