Source/JavaScriptCore/b3/B3Opcode.h

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#ifndef B3Opcode_h
#define B3Opcode_h

#if ENABLE(B3_JIT)

#include "B3Type.h"
#include <wtf/Optional.h>
#include <wtf/StdLibExtras.h>

namespace JSC { namespace B3 {

enum Opcode : int16_t {
    // A no-op that returns Void, useful for when you want to remove a value.
    Nop,
    
    // Polymorphic identity, usable with any value type.
    Identity,

    // Constants. Use the ConstValue* classes. Constants exist in the control flow, so that we can
    // reason about where we would construct them. Large constants are expensive to create.
    Const32,
    Const64,
    ConstDouble,

    // The magical stack slot. This is viewed as executing at the top of the program regardless of
    // where in control flow you put it. Each instance of a StackSlot Value gets a disjoint range of
    // stack memory. Use the StackSlotValue class.
    StackSlot,

    // The magical argument register. This is viewed as executing at the top of the program
    // regardless of where in control flow you put it, and the compiler takes care to ensure that we
    // don't clobber the value by register allocation or calls (either by saving the argument to the
    // stack or preserving it in a callee-save register). Use the ArgumentRegValue class. The return
    // type is either pointer() (for GPRs) or Double (for FPRs).
    ArgumentReg,

    // The frame pointer. You can put this anywhere in control flow but it will always yield the
    // frame pointer, with a caveat: if our compiler changes the frame pointer temporarily for some
    // silly reason, the FramePointer intrinsic will return where the frame pointer *should* be not
    // where it happens to be right now.
    FramePointer,

    // Polymorphic math, usable with any value type.
    Add,
    Sub,
    Mul,
    Div, // All bets are off as to what will happen when you execute this for -2^31/-1 and x/0.

    // Integer math.
    ChillDiv, // doesn't trap ever, behaves like JS (x/y)|0.
    Mod,
    BitAnd,
    BitOr,
    BitXor,
    Shl,
    SShr, // Arithmetic Shift.
    ZShr, // Logical Shift.

    // Casts and such.
    // Takes and returns Int32:
    SExt8,
    SExt16,
    // Takes Int32 and returns Int64:
    SExt32,
    ZExt32,
    // Takes Int64 and returns Int32:
    Trunc,
    // Takes and returns Double:
    FRound,
    // Takes ints and returns Double:
    IToD,
    // Takes Double and returns Int32:
    DToI32,

    // Polymorphic comparisons, usable with any value type. Returns int32 0 or 1. Note that "Not"
    // is just Equal(x, 0), and "ToBoolean" is just NotEqual(x, 0).
    Equal,
    NotEqual,
    LessThan,
    GreaterThan,
    LessEqual,
    GreaterEqual,

    // Integer comparisons. Returns int32 0 or 1.
    Above,
    Below,
    AboveEqual,
    BelowEqual,

    // Memory loads. Opcode indicates how we load and the loaded type. These use MemoryValue.
    // These return Int32:
    Load8Z,
    Load8S,
    Load16Z,
    Load16S,
    // This returns Double:
    LoadFloat,
    // This returns whatever the return type is:
    Load,

    // Memory stores. Opcode indicates how the value is stored. These use MemoryValue.
    // These take an Int32 value:
    Store8,
    Store16,
    // This takes a Double value:
    StoreFloat,
    // This is a polymorphic store for Int32, Int64, and Double:
    Store,

    // This is a regular ordinary C function call, using the system C calling convention. Make sure
    // that the arguments are passed using the right types. The first argument is the callee.
    CCall,

    // This is a patchpoint. Use the PatchpointValue class. This is viewed as behaving like a call,
    // but only emits code via a code generation callback. That callback gets to emit code inline.
    // You can pass a stackmap along with constraints on how each stackmap argument must be passed.
    // It's legal to request that a stackmap argument is in some register and it's legal to request
    // that a stackmap argument is at some offset from the top of the argument passing area on the
    // stack.
    Patchpoint,

    // Checked math. Use the CheckValue class. Like a Patchpoint, this takes a code generation
    // callback. That callback gets to emit some code after the epilogue, and gets to link the jump
    // from the check, and the choice of registers. You also get to supply a stackmap. Note that you
    // are not allowed to jump back into the mainline code from your slow path, since the compiler
    // will assume that the execution of these instructions proves that overflow didn't happen. For
    // example, if you have two CheckAdd's:
    //
    // a = CheckAdd(x, y)
    // b = CheckAdd(x, y)
    //
    // Then it's valid to change this to:
    //
    // a = CheckAdd(x, y)
    // b = Identity(a)
    //
    // This is valid regardless of the callbacks used by the two CheckAdds. They may have different
    // callbacks. Yet, this transformation is valid even if they are different because we know that
    // after the first CheckAdd executes, the second CheckAdd could not have possibly taken slow
    // path. Therefore, the second CheckAdd's callback is irrelevant.
    CheckAdd,
    CheckSub,
    CheckMul,

    // Check that side-exits. Use the CheckValue class. Like CheckAdd and friends, this has a
    // stackmap with a generation callback. This takes an int argument that this branches on, with
    // full branch fusion in the instruction selector. A true value jumps to the generator's slow
    // path.
    Check,

    // SSA support, in the style of DFG SSA.
    Upsilon, // This uses the UpsilonValue class.
    Phi,

    // Jump. Uses the ControlValue class.
    Jump,
    
    // Polymorphic branch, usable with any integer type. Branches if not equal to zero. Uses the
    // ControlValue class, with the 0-index successor being the true successor.
    Branch,

    // Switch. Switches over either Int32 or Int64. Uses the SwitchValue class.
    Switch,

    // Return. Note that B3 procedures don't know their return type, so this can just return any
    // type. Uses the ControlValue class.
    Return,

    // This is a terminal that indicates that we will never get here. Uses the ControlValue class.
    Oops
};

inline bool isCheckMath(Opcode opcode)
{
    switch (opcode) {
    case CheckAdd:
    case CheckSub:
    case CheckMul:
        return true;
    default:
        return false;
    }
}

Optional<Opcode> invertedCompare(Opcode, Type);

inline Opcode constPtrOpcode()
{
    if (is64Bit())
        return Const64;
    return Const32;
}

} } // namespace JSC::B3

namespace WTF {

class PrintStream;

void printInternal(PrintStream&, JSC::B3::Opcode);

} // namespace WTF

#endif // ENABLE(B3_JIT)

#endif // B3Opcode_h