expr.h

/*
  Copyright (c) 2010-2011, Intel Corporation
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.

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      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.


   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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*/

/** @file expr.h
    @brief Expr abstract base class and expression implementations
*/

#ifndef ISPC_EXPR_H
#define ISPC_EXPR_H 1

#include "ispc.h"
#include "type.h"

class FunctionSymbolExpr;

/** @brief Expr is the abstract base class that defines the interface that
    all expression types must implement.
 */
class Expr : public ASTNode {
public:
    Expr(SourcePos p) : ASTNode(p) { }

    /** This is the main method for Expr implementations to implement.  It
        should call methods in the FunctionEmitContext to emit LLVM IR
        instructions to the current basic block in order to generate an
        llvm::Value that represents the expression's value. */
    virtual llvm::Value *GetValue(FunctionEmitContext *ctx) const = 0;

    /** For expressions that can provide an lvalue (e.g. array indexing),
        this function should emit IR that computes the expression's lvalue
        and returns the corresponding llvm::Value.  Expressions that can't
        provide an lvalue should leave this unimplemented; the default
        implementation returns NULL.  */
    virtual llvm::Value *GetLValue(FunctionEmitContext *ctx) const;

    /** Returns the Type of the expression. */
    virtual const Type *GetType() const = 0;

    /** For expressions that have values based on a symbol (e.g. regular
        symbol references, array indexing, etc.), this returns a pointer to
        that symbol. */
    virtual Symbol *GetBaseSymbol() const;

    /** If this is a constant expression that can be converted to a
        constant of the given type, this method should return the
        corresponding llvm::Constant value.  Otherwise it should return
        NULL. */
    virtual llvm::Constant *GetConstant(const Type *type) const;

    /** This method should perform early optimizations of the expression
        (constant folding, etc.) and return a pointer to the resulting
        expression.  If an error is encountered during optimization, NULL
        should be returned. */
    virtual Expr *Optimize() = 0;

    /** This method should perform type checking of the expression and
        return a pointer to the resulting expression.  If an error is
        encountered, NULL should be returned. */
    virtual Expr *TypeCheck() = 0;

    /** Prints the expression to standard output (used for debugging). */
    virtual void Print() const = 0;

    /** This method tries to convert the expression to the given type.  In
        the event of failure, if the failureOk parameter is true, then no
        error is issued.  If failureOk is false, then an error is printed
        that incorporates the given error message string.  In either
        failure case, NULL is returned.  */
    Expr *TypeConv(const Type *type, const char *errorMsgBase = NULL, 
                   bool failureOk = false, bool issuePrecisionWarnings = true);
};


/** @brief Unary expression */
class UnaryExpr : public Expr {
public:
    enum Op {
        PreInc,      ///< Pre-increment
        PreDec,      ///< Pre-decrement 
        PostInc,     ///< Post-increment
        PostDec,     ///< Post-decrement
        Negate,      ///< Negation
        LogicalNot,  ///< Logical not
        BitNot,      ///< Bit not
    };

    UnaryExpr(Op op, Expr *expr, SourcePos pos);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;
    Expr *Optimize();
    Expr *TypeCheck();

private:
    const Op op;
    Expr *expr;
};


/** @brief Binary expression */
class BinaryExpr : public Expr {
public:
    enum Op {
        Add,           ///< Addition
        Sub,           ///< Subtraction
        Mul,           ///< Multiplication
        Div,           ///< Division
        Mod,           ///< Modulus
        Shl,           ///< Shift left
        Shr,           ///< Shift right

        Lt,            ///< Less than
        Gt,            ///< Greater than
        Le,            ///< Less than or equal
        Ge,            ///< Greater than or equal
        Equal,         ///< Equal
        NotEqual,      ///< Not equal

        BitAnd,        ///< Bitwise AND
        BitXor,        ///< Bitwise XOR
        BitOr,         ///< Bitwise OR
        LogicalAnd,    ///< Logical AND
        LogicalOr,     ///< Logical OR

        Comma,         ///< Comma operator
    };

    BinaryExpr(Op o, Expr *a, Expr *b, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;

    Expr *Optimize();
    Expr *TypeCheck();

private:
    const Op op;
    Expr *arg0, *arg1;
};


/** @brief Assignment expression */
class AssignExpr : public Expr {
public:
    enum Op {
        Assign,     ///< Regular assignment
        MulAssign,  ///< *= assignment
        DivAssign,  ///< /= assignment
        ModAssign,  ///< %= assignment
        AddAssign,  ///< += assignment
        SubAssign,  ///< -= assignment
        ShlAssign,  ///< <<= assignment
        ShrAssign,  ///< >>= assignment
        AndAssign,  ///< &= assignment
        XorAssign,  ///< ^= assignment
        OrAssign,   ///< |= assignment
    };

    AssignExpr(Op o, Expr *a, Expr *b, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;

    Expr *Optimize();
    Expr *TypeCheck();

private:
    const Op op;
    Expr *lvalue, *rvalue;
};


/** @brief Selection expression, corresponding to "test ? a : b".  

    Returns the value of "a" or "b", depending on the value of "test".
*/
class SelectExpr : public Expr {
public:
    SelectExpr(Expr *test, Expr *a, Expr *b, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;

    Expr *Optimize();
    Expr *TypeCheck();

private:
    Expr *test, *expr1, *expr2;
};


/** @brief A list of expressions.

    These are mostly used for representing curly-brace delimited
    initializers for initializers for complex types and for representing
    the arguments passed to a function call.
 */
class ExprList : public Expr {
public:
    ExprList(SourcePos p) : Expr(p) { }
    ExprList(Expr *e, SourcePos p) : Expr(p) { exprs.push_back(e); }

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;
    llvm::Constant *GetConstant(const Type *type) const;
    ExprList *Optimize();
    ExprList *TypeCheck();

    std::vector<Expr *> exprs;
};


/** @brief Expression representing a function call.
 */
class FunctionCallExpr : public Expr {
public:
    FunctionCallExpr(Expr *func, ExprList *args, SourcePos p, bool isLaunch);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;

    Expr *Optimize();
    Expr *TypeCheck();

private:
    Expr *func;
    ExprList *args;
    bool isLaunch;

    void resolveFunctionOverloads();
    bool tryResolve(bool (*matchFunc)(Expr *, const Type *));
};


/** @brief Expression representing indexing into something with an integer
    offset.

    This is used for both array indexing and indexing into VectorTypes. 
*/
class IndexExpr : public Expr {
public:
    IndexExpr(Expr *arrayOrVector, Expr *index, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    llvm::Value *GetLValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Symbol *GetBaseSymbol() const;
    void Print() const;

    Expr *Optimize();
    Expr *TypeCheck();

private:
    Expr *arrayOrVector, *index;
};


/** @brief Expression representing member selection ("foo.bar").
 *
 *  This will also be overloaded to deal with swizzles.
 */
class MemberExpr : public Expr {
public:
    static MemberExpr* create(Expr *expr, const char *identifier,
                              SourcePos pos, SourcePos identifierPos);

    MemberExpr(Expr *expr, const char *identifier, SourcePos pos, 
               SourcePos identifierPos);

    virtual llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    virtual llvm::Value *GetLValue(FunctionEmitContext *ctx) const;
    virtual const Type *GetType() const;
    virtual Symbol *GetBaseSymbol() const;
    virtual void Print() const;
    virtual Expr *Optimize();
    virtual Expr *TypeCheck();
    virtual int getElementNumber() const;

protected:
    std::string getCandidateNearMatches() const;

    Expr *expr;
    std::string identifier;
    const SourcePos identifierPos;
};


/** @brief Expression representing a compile-time constant value.  

    This class can currently represent compile-time constants of anything
    that is an AtomicType or an EnumType; for anything more complex, we
    don't currently have a representation of a compile-time constant that
    can be further reasoned about.
 */
class ConstExpr : public Expr {
public:
    /** Create a ConstExpr from a uniform int8 value */
    ConstExpr(const Type *t, int8_t i, SourcePos p);
    /** Create a ConstExpr from a varying int8 value */
    ConstExpr(const Type *t, int8_t *i, SourcePos p);
    /** Create a ConstExpr from a uniform uint8 value */
    ConstExpr(const Type *t, uint8_t u, SourcePos p);
    /** Create a ConstExpr from a varying uint8 value */
    ConstExpr(const Type *t, uint8_t *u, SourcePos p);

    /** Create a ConstExpr from a uniform int16 value */
    ConstExpr(const Type *t, int16_t i, SourcePos p);
    /** Create a ConstExpr from a varying int16 value */
    ConstExpr(const Type *t, int16_t *i, SourcePos p);
    /** Create a ConstExpr from a uniform uint16 value */
    ConstExpr(const Type *t, uint16_t u, SourcePos p);
    /** Create a ConstExpr from a varying uint16 value */
    ConstExpr(const Type *t, uint16_t *u, SourcePos p);

    /** Create a ConstExpr from a uniform int32 value */
    ConstExpr(const Type *t, int32_t i, SourcePos p);
    /** Create a ConstExpr from a varying int32 value */
    ConstExpr(const Type *t, int32_t *i, SourcePos p);
    /** Create a ConstExpr from a uniform uint32 value */
    ConstExpr(const Type *t, uint32_t u, SourcePos p);
    /** Create a ConstExpr from a varying uint32 value */
    ConstExpr(const Type *t, uint32_t *u, SourcePos p);

    /** Create a ConstExpr from a uniform float value */
    ConstExpr(const Type *t, float f, SourcePos p);
    /** Create a ConstExpr from a varying float value */
    ConstExpr(const Type *t, float *f, SourcePos p);

    /** Create a ConstExpr from a uniform double value */
    ConstExpr(const Type *t, double d, SourcePos p);
    /** Create a ConstExpr from a varying double value */
    ConstExpr(const Type *t, double *d, SourcePos p);

    /** Create a ConstExpr from a uniform int64 value */
    ConstExpr(const Type *t, int64_t i, SourcePos p);
    /** Create a ConstExpr from a varying int64 value */
    ConstExpr(const Type *t, int64_t *i, SourcePos p);
    /** Create a ConstExpr from a uniform uint64 value */
    ConstExpr(const Type *t, uint64_t i, SourcePos p);
    /** Create a ConstExpr from a varying uint64 value */
    ConstExpr(const Type *t, uint64_t *i, SourcePos p);

    /** Create a ConstExpr from a uniform bool value */
    ConstExpr(const Type *t, bool b, SourcePos p);
    /** Create a ConstExpr from a varying bool value */
    ConstExpr(const Type *t, bool *b, SourcePos p);

    /** Create a ConstExpr of the same type as the given old ConstExpr,
        with values given by the "vales" parameter. */
    ConstExpr(ConstExpr *old, double *values);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;
    llvm::Constant *GetConstant(const Type *type) const;

    Expr *TypeCheck();
    Expr *Optimize();

    /** Return the ConstExpr's values as booleans, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsBool(bool *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as int8s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsInt8(int8_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as uint8s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsUInt8(uint8_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as int16s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsInt16(int16_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as uint16s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsUInt16(uint16_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as int32s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsInt32(int32_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as uint32s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsUInt32(uint32_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as floats, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsFloat(float *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as int64s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsInt64(int64_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as uint64s, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsUInt64(uint64_t *, bool forceVarying = false) const;

    /** Return the ConstExpr's values as doubles, doing type conversion
        from the actual type if needed.  If forceVarying is true, then type
        convert to 'varying' so as to always return a number of values
        equal to the target vector width into the given pointer. */
    int AsDouble(double *, bool forceVarying = false) const;

    /** Return the number of values in the ConstExpr; should be either 1,
        if it has uniform type, or the target's vector width if it's
        varying. */
    int Count() const;

private:
    AtomicType::BasicType getBasicType() const;

    const Type *type;
    union {
        int8_t int8Val[ISPC_MAX_NVEC];
        uint8_t uint8Val[ISPC_MAX_NVEC];
        int16_t int16Val[ISPC_MAX_NVEC];
        uint16_t uint16Val[ISPC_MAX_NVEC];
        int32_t int32Val[ISPC_MAX_NVEC];
        uint32_t uint32Val[ISPC_MAX_NVEC];
        bool boolVal[ISPC_MAX_NVEC];
        float floatVal[ISPC_MAX_NVEC];
        double doubleVal[ISPC_MAX_NVEC];
        int64_t int64Val[ISPC_MAX_NVEC];
        uint64_t uint64Val[ISPC_MAX_NVEC];
    };
};


/** @brief Expression representing a type cast of the given expression to a
    probably-different type. */
class TypeCastExpr : public Expr {
public:
    TypeCastExpr(const Type *t, Expr *e, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    void Print() const;
    Expr *TypeCheck();
    Expr *Optimize();

private:
    const Type *type;
    Expr *expr;
};


/** @brief Expression that represents taking a reference of a (non-reference)
    variable. */
class ReferenceExpr : public Expr {
public:
    ReferenceExpr(Expr *e, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Symbol *GetBaseSymbol() const;
    void Print() const;
    Expr *TypeCheck();
    Expr *Optimize();

private:
    Expr *expr;
};


/** @brief Expression that represents dereferencing a reference to get its
    value. */
class DereferenceExpr : public Expr {
public:
    DereferenceExpr(Expr *e, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    llvm::Value *GetLValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Symbol *GetBaseSymbol() const;
    void Print() const;
    Expr *TypeCheck();
    Expr *Optimize();

private:
    Expr *expr;
};


/** @brief Expression representing a symbol reference in the program */
class SymbolExpr : public Expr {
public:
    SymbolExpr(Symbol *s, SourcePos p);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    llvm::Value *GetLValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Symbol *GetBaseSymbol() const;
    Expr *TypeCheck();
    Expr *Optimize();
    void Print() const;

private:
    Symbol *symbol;
};


/** @brief Expression representing a function symbol in the program (generally
    used for a function call).
 */    
class FunctionSymbolExpr : public Expr {
public:
    FunctionSymbolExpr(std::vector<Symbol *> *candidateFunctions, 
                       SourcePos pos);

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Symbol *GetBaseSymbol() const;
    Expr *TypeCheck();
    Expr *Optimize();
    void Print() const;

private:
    friend class FunctionCallExpr;

    /** All of the functions with the name given in the function call;
        there may be more then one, in which case we need to resolve which
        overload is the best match. */
    std::vector<Symbol *> *candidateFunctions;

    /** The actual matching function found after overload resolution; this
        value is set by FunctionCallExpr::resolveFunctionOverloads() */
    Symbol *matchingFunc;
};


/** @brief A sync statement in the program (waits for all launched tasks before
    proceeding). */
class SyncExpr : public Expr {
public:
    SyncExpr(SourcePos p) : Expr(p) { }

    llvm::Value *GetValue(FunctionEmitContext *ctx) const;
    const Type *GetType() const;
    Expr *TypeCheck();
    Expr *Optimize();
    void Print() const;
};

#endif // ISPC_EXPR_H