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// bytecode.h
#ifndef SLANG_BYTECODE_H_INCLUDED
#define SLANG_BYTECODE_H_INCLUDED
// This file defines a "bytecode" format for storing shader code
// that has been generated via the Slang IR. The bytecode has
// two main goals, that can end up in a bit of conflict:
//
// 1) It is the official serialized form of the Slang IR, and
// so it is of some importance that constructs in the IR be
// able to round-trip through the bytecode.
//
// 2) It should support being directly executed/interpreted,
// so that Slang code can be executed on CPUs when
// performance isn't critical (or when a JIT just isn't
// an option).
//
#include "../core/basic.h"
namespace Slang
{
template<typename T>
struct BytecodeGenerationPtr;
// A "pointer" stored in a serialized bytecode file, which
// is represented as a byte offset relative to itself.
//
template<typename T>
struct BCPtr
{
typedef int32_t RawVal;
RawVal rawVal;
BCPtr() : rawVal(0) {}
BCPtr(T* ptr)
: rawVal(0)
{
*this = ptr;
}
BCPtr(BCPtr<T> const& ptr)
: rawVal(0)
{
*this = ptr.getPtr();
}
void operator=(BCPtr<T> const& ptr)
{
*this = ptr.getPtr();
}
void operator=(T* ptr)
{
if (ptr)
{
rawVal = (char*)ptr - (char*)this;
}
else
{
rawVal = 0;
}
}
operator T*() const { return getPtr(); }
T* getPtr() const
{
if(!rawVal) return nullptr;
return (T*)((char const*)this + rawVal);
}
};
struct BCType
{
uint32_t op;
};
struct BCSymbol
{
// The opcode that was used to define
// this symbol; used to categorize things
uint32_t op;
// The type of the symbol is represent
// as an index into the global-scope symbol
// list of the module.
//
// Note: This currently precludes having
// a register with a type that is not
// statically determined, but that is
// probably okay.
uint32_t typeGlobalID;
// The name of this symbol (which might
// be a mangled name at some point,
// so it is really only meant to be
// used for linkage...)
BCPtr<char> name;
};
typedef uint8_t BCOp;
struct BCReg : BCSymbol
{
// The index of the variable/register
// that should be stored immediately
// preceding this one.
uint32_t previousVarIndexPlusOne;
};
struct BCConst
{
// The ID of the symbol in the global
// scope that we are trying to refer
// to.
//
// TODO: eventually, if we have general
// nesting, then this might be the
// entry in the outer scope that
// is being referenced.
uint32_t globalID;
};
struct BCBlock
{
// The start of the bytecode for this block
BCPtr<BCOp> code;
// The list of parameters of the block
uint32_t paramCount;
BCPtr<BCReg> params;
};
struct BCFunc : BCSymbol
{
// A list of "registers" used to hold
// intermediate values during execution
// of this function.
uint32_t regCount;
BCPtr<BCReg> regs;
// The basic blocks of the function
uint32_t blockCount;
BCPtr<BCBlock> blocks;
// A list of "constants" which are values
// from the global scope that this function
// wants to be able to refer to. We could
// just encode global values directly,
// but this would make the encoding less dense.
uint32_t constCount;
BCPtr<BCConst> consts;
// Data for "nested" symbols (e.g., a function
// nested inside this function).
uint32_t nestedSymbolCount;
BCPtr<BCPtr<BCSymbol>> nestedSymbols;
};
// A module is encoded more or less like a function.
struct BCModule : BCFunc
{
};
struct BCHeader
{
char magic[8];
uint32_t version;
// TODO: probably want a section-based file
// format so that we can add/remove different
// kinds of data without having to revise
// the schema here.
// The bytecode representation of the module
BCPtr<BCModule> module;
};
}
#endif
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