llvm/lib/Target/X86/X86InstrSel.td
2004-04-06 19:34:00 +00:00

394 lines
18 KiB
C++

//===- X86InstrSel.td - Describe the X86 Instruction Selector -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is used by the instruction selector and is used to map
// LLVM instructions to a corresponding set of machine instructions
//
//
//===----------------------------------------------------------------------===//
include "../Target.td"
// ret br switch invoke unwind
// add sub mul div rem setcc (eq ne lt gt le ge)
// and or xor sbl sbr
// malloc free alloca load store
// getelementptr phi cast call vanext vaarg
class InstrSubclass<int v> {
int Value = v;
}
// provide a grouping of InstrSubclasses
class InstrSubclassCollection<string pre, string post, list<InstrSubclass> l> {
list<InstrSubclass> List = l;
string PreCode = pre;
string PostCode = post;
}
// virtual registers
let Namespace = "Virtual" in {
def DestReg : Register;
def DestRegp1 : Register; // DestReg+1
def Op0Reg : Register;
def Op0Regp1 : Register; // Op0Reg+1
def Op1Reg : Register;
def Op1Regp1 : Register; // Op1Reg+1
def TmpReg01 : Register;
def TmpReg01p1: Register;
def TmpReg02 : Register;
def TmpReg02p1: Register;
def NullReg : Register; // represents no register
}
class InstrClass<string n, string fn, string pre, string post, list<InstrSubclassCollection> l> {
string FunctionName = fn;
string InstructionName = n;
string PreCode = pre;
string PostCode = post;
// add lists of what subclasses this InstrClass supports
list<InstrSubclassCollection> Supports = l;
}
// helper class to build BMI instruction
class addedOperand<string op> {
string Name = op;
}
def MBI_Reg : addedOperand<"Reg">;
def MBI_GlobalAddr : addedOperand<"GlobalAddr">;
def MBI_ZImm : addedOperand<"ZImm">;
def MBI_DirectMem : addedOperand<"DirectMem">;
def MBI_RegOffset : addedOperand<"RegOffset">;
def MBI_FrameRef : addedOperand<"FrameRef">;
def MBI_ConstPoolRef : addedOperand<"ConstPoolRef">;
def MBI_CCReg : addedOperand<"CCReg">;
def MBI_RegDef : addedOperand<"RegDef">;
def MBI_PCDisp : addedOperand<"PCDisp">;
def MBI_MReg : addedOperand<"MReg">;
def MBI_SImm : addedOperand<"SImm">;
def MBI_MBB : addedOperand<"MBB">;
def MBI_FrameIndex : addedOperand<"FrameIndex">;
def MBI_ConstPoolIdx : addedOperand<"ConstPoolIdx">;
def MBI_ExternSymbol : addedOperand<"ExternSymbol">;
class TargInstr<string n, int numops, list<addedOperand> lops> {
string Name = n; // make this a reference to the Instruction class
string Namespace;
int NumOperands = numops;
list<addedOperand> Params = lops; // will this work for mem-mem instrs, destination is implicitly a register
} //TargInstr
let Namespace = "Virtual" in {
// virtual instructions for creating registers
def CreateRegInt : TargInstr<"CreateRegInt",0,[]>;
def CreateRegByte : TargInstr<"CreateRegByte",0,[]>;
def CreateRegShort: TargInstr<"CreateRegShort",0,[]>;
def CreateRegLong : TargInstr<"CreateRegLong",0,[]>;
def CreateRegUInt : TargInstr<"CreateRegUInt",0,[]>;
def CreateRegUByte : TargInstr<"CreateRegUByte",0,[]>;
def CreateRegUShort: TargInstr<"CreateRegUShort",0,[]>;
def CreateRegULong : TargInstr<"CreateRegULong",0,[]>;
def CreateRegFloat : TargInstr<"CreateRegFloat",0,[]>;
def CreateRegDouble : TargInstr<"CreateRegDouble",0,[]>;
def CreateRegPointer: TargInstr<"CreateRegPointer",0,[]>;
def NullInstr : TargInstr<"NullInstruction",0,[]>; // ignored
}
class TargInstrSet<InstrClass c, string pre, string post, list<InstrSubclass> l, list<TargInstr> targs, list<list<string>> r> {
InstrClass Class = c;
list<InstrSubclass> List = l;
list<TargInstr> Instructions = targs;
list< list<string> > Operands = r; // generalized for all operand types
string PreCode = pre;
string PostCode = post;
}
// --------------------------------------------------------------------
// Begin architecture-specific information
// --------------------------------------------------------------------
include "X86RegisterInfo.td"
include "X86InstrSelInfo.td"
// set up the subclasses of instructions
// value is what the subclass's case value
def cByte : InstrSubclass<1>;
def cInt : InstrSubclass<2>;
def cShort : InstrSubclass<3>;
def cFP : InstrSubclass<4>;
def cLong : InstrSubclass<5>;
def EQ : InstrSubclass<1>;
def NE : InstrSubclass<2>;
def LT : InstrSubclass<3>;
def GE : InstrSubclass<4>;
def GT : InstrSubclass<5>;
def LE : InstrSubclass<6>;
def True : InstrSubclass<1>;
def False : InstrSubclass<0>;
def NegOne : InstrSubclass<-1>;
def PosOne : InstrSubclass<1>;
def Cons :InstrSubclass<2>;
def Other : InstrSubclass<0>;
def Regular: InstrSubclass<0>;
def Zero : InstrSubclass<0>;
def NoOps : InstrSubclass<0>;
def Ops : InstrSubclass<1>;
def Signed : InstrSubclass<0>;
def Unsigned : InstrSubclass<1>;
def SuccessorIsNextBB : InstrSubclass<0>;
def SuccessorIsNotNextBB: InstrSubclass<1>;
def Cond: InstrSubclass<0>;
def Uncond: InstrSubclass<1>;
def ConstTwo: InstrSubclass<2>;
def ConstNotTwo: InstrSubclass<3>;
def Reg: InstrSubclass<6>;
// group subclasses, specify how to determine instruction subclass
def OperandSize: InstrSubclassCollection<"unsigned OperandSize = getClassB(Op0Val->getType());","", [cByte, cShort, cInt, cFP, cLong]>;
def Conditional: InstrSubclassCollection<"unsigned Conditional;", "", [EQ, NE, LT, GE, GT, LE]>;
def SpecialCase: InstrSubclassCollection<"unsigned SpecialCase;", "", [True, False]>;
//TODO write funcs for separating out special cases
def AddSpecialCases: InstrSubclassCollection<"Subclasses AddSpecialCases = Other;", "", [NegOne,PosOne,Cons,Other]>;
def SubSpecialCases: InstrSubclassCollection<"unsigned SubSpecialCases = Other;", "", [NegOne,PosOne,Cons,Other]>;
def XorSpecialCases: InstrSubclassCollection<"unsigned XorSpecialCases = Other;","", [NegOne,Other]>;
// Instruction subclasses, as defined in llvm/Instructions.h:
// iTerminators.h : ReturnInst, BranchInst, SwitchInst, InvokeInst, UnwindInst
// iPHINode.h : PHINode,
// iOperators.h : SetCondInst,
// iMemory.h : AllocationInst, MallocInst, AllocaInst, FreeInst, LoadInst, StoreInst, GetElementPtrInst,
// iOther.h : CastInst, CallInst, ShiftInst, VANextInst, VAArgInst,
// InstrTypes.h : TerminatorInst, BinaryOperator
// general classes of LLVM instructions, and the subclass sets that apply to them
def add : InstrClass<"BinaryOperator","Add","","",[AddSpecialCases, OperandSize]>;
def sub : InstrClass<"BinaryOperator","Sub","","",[SubSpecialCases, OperandSize]>;
// def mul : InstrClass<"BinaryOperator","Mul","","",[OperandSize]>;
// def div : InstrClass<"BinaryOperator","Div","","",[OperandSize]>;
// def rem : InstrClass<"BinaryOperator","Rem","","",[OperandSize]>;
def logic_and : InstrClass<"BinaryOperator","And","","",[OperandSize]>;
def logic_or : InstrClass<"BinaryOperator","Or","","",[OperandSize]>;
def logic_xor : InstrClass<"BinaryOperator","Xor","","",[XorSpecialCases, OperandSize]>;
// //def mov : InstrClass<"ShiftInst","Mov","","",[OperandSize]>;
// def setcc: InstrClass<"SetCondInst","SetCondInst","","",[OperandSize]>;
// def branch : InstrClass<"BranchInst","BranchInst","","",[Conditional]>;
// def retrn : InstrClass<"ReturnInst","ReturnInst","","",[]>;
// definition of machine instructions for instruction subclasses
// ADD
def ADD_Other_cByte : TargInstrSet<add,"","",[Other,cByte],[CreateRegByte,ADDrr8],[["EAX"],["EAX","Op0Reg","Op1Reg"]]>;
def ADD_Other_cShort : TargInstrSet<add,"","",[Other,cShort],[ADDrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Other_cInt : TargInstrSet<add,"","",[Other,cInt],[ADDrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Other_cLong : TargInstrSet<add,"","",[Other,cLong],[ADDrr32,ADCrr32],[["DestReg","Op0Reg","Op1Reg"],["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Other_cFP : TargInstrSet<add,"","",[Other,cFP],[FpADD],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Constant_cByte : TargInstrSet<add,"","",[Cons,cByte],[ADDri8],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Constant_cShort :TargInstrSet<add,"","",[Cons,cShort],[ADDri16],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_Constant_cInt :TargInstrSet<add,"","",[Cons,cInt],[ADDri32],[["DestReg","Op0Reg","Op1Reg"]]>;
def ADD_PosOne_cByte : TargInstrSet<add,"","",[PosOne,cByte],[INCr8],[["DestReg","Op0Reg"]]>;
def ADD_PosOne_cShort : TargInstrSet<add,"","",[PosOne,cShort],[INCr16],[["DestReg","Op0Reg"]]>;
def ADD_PosOne_cInt : TargInstrSet<add,"","",[PosOne,cInt],[INCr32],[["DestReg","Op0Reg"]]>;
def ADD_NegOne_cByte : TargInstrSet<add,"","",[NegOne,cByte],[DECr8],[["DestReg","Op0Reg"]]>;
def ADD_NegOne_cShort : TargInstrSet<add,"","",[NegOne,cShort],[DECr16],[["DestReg","Op0Reg"]]>;
def ADD_NegOne_cInt : TargInstrSet<add,"","",[NegOne,cInt],[DECr32],[["DestReg","Op0Reg"]]>;
// SUBTRACT
def SUB_Other_cByte : TargInstrSet<sub,"","",[Other,cByte],[CreateRegByte,SUBrr8],[["EAX"],["EAX","Op0Reg","Op1Reg"]]>;
def SUB_Other_cShort : TargInstrSet<sub,"","",[Other,cShort],[SUBrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Other_cInt : TargInstrSet<sub,"","",[Other,cInt],[SUBrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Other_cLong : TargInstrSet<sub,"","",[Other,cLong],[SUBrr32,SUBrr32],[["DestReg","Op0Reg","Op1Reg"],["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Other_cFP : TargInstrSet<sub,"","",[Other,cFP],[FpSUB],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Constant_cByte : TargInstrSet<sub,"","",[Cons,cByte],[SUBri8],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Constant_cShort :TargInstrSet<sub,"","",[Cons,cShort],[SUBri16],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_Constant_cInt :TargInstrSet<sub,"","",[Cons,cInt],[SUBri32],[["DestReg","Op0Reg","Op1Reg"]]>;
def SUB_PosOne_cByte : TargInstrSet<sub,"","",[PosOne,cByte],[DECr8],[["DestReg","Op0Reg"]]>;
def SUB_PosOne_cShort : TargInstrSet<sub,"","",[PosOne,cShort],[DECr16],[["DestReg","Op0Reg"]]>;
def SUB_PosOne_cInt : TargInstrSet<sub,"","",[PosOne,cInt],[DECr32],[["DestReg","Op0Reg"]]>;
def SUB_NegOne_cByte : TargInstrSet<sub,"","",[NegOne,cByte],[INCr8],[["DestReg","Op0Reg"]]>;
def SUB_NegOne_cShort : TargInstrSet<sub,"","",[NegOne,cShort],[INCr16],[["DestReg","Op0Reg"]]>;
def SUB_NegOne_cInt : TargInstrSet<sub,"","",[NegOne,cInt],[INCr32],[["DestReg","Op0Reg"]]>;
// def SHIFT_S_L_Const_Byte :
// def SHIFT_S_L_Const_Short :
// def SHIFT_S_L_Const_Int :
// def SHIFT_S_L_Const_SHLDIR32 :
// def SHIFT_S_L_Reg_Byte :
// def SHIFT_S_L_Reg_Short :
// def SHIFT_S_L_Reg_Int :
// def SHIFT_S_R_Const_Byte :
// def SHIFT_S_R_Const_Short :
// def SHIFT_S_R_Const_Int :
// def SHIFT_S_R_Const_SHRDIR32 :
// def SHIFT_S_R_Reg_Byte :
// def SHIFT_S_R_Reg_Short :
// def SHIFT_S_R_Reg_Int :
// def SHIFT_U_L_Const_Byte :
// def SHIFT_U_L_Const_Short :
// def SHIFT_U_L_Const_Int :
// def SHIFT_U_L_Const_SHLDIR32 :
// def SHIFT_U_L_Reg_Byte :
// def SHIFT_U_L_Reg_Short :
// def SHIFT_U_L_Reg_Int :
// def SHIFT_U_R_Const_Byte :
// def SHIFT_U_R_Const_Short :
// def SHIFT_U_R_Const_Int :
// def SHIFT_U_R_Const_SHRDIR32 :
// def SHIFT_U_R_Reg_Byte :
// def SHIFT_U_R_Reg_Short :
// def SHIFT_U_R_Reg_Int :
// def CMP_i_Byte : TargInstrSet<setcc,"","",[Constant,cByte],[CMPri8],[["DestReg","Op0Reg","Op1Val"]]>;
// def CMP_i_Short : TargInstrSet<setcc,"","",[Constant,cShort],[CMPri16],[["DestReg","Op0Reg","Op1Val"]]>;
// def CMP_i_Int : TargInstrSet<setcc,"","",[Constant,cInt],[CMPri32],[["DestReg","Op0Reg","Op1Val"]]>;
// //def CMP_i_Long : // not supported
// def CMP_z_Byte : TargInstrSet<setcc,"ConstantInt *CI = dyn_cast<ConstantInt>(Op1); uint64_t Op1v = cast<ConstantInt>(CI)->getRawValue(); Op1v &= (1ULL << (8 << Class)) - 1;","",[Zero,cByte],[TESTrr8],[["DestReg","Op0Reg","Op0Reg"]]>;
// def CMP_z_Short : TargInstrSet<setcc,"ConstantInt *CI = dyn_cast<ConstantInt>(Op1); uint64_t Op1v = cast<ConstantInt>(CI)->getRawValue(); Op1v &= (1ULL << (8 << Class)) - 1;","",[Zero,cShort],[TESTrr16],[["DestReg","Op0Reg","Op0Reg"]]>;
// def CMP_z_Int : TargInstrSet<setcc,"ConstantInt *CI = dyn_cast<ConstantInt>(Op1); uint64_t Op1v = cast<ConstantInt>(CI)->getRawValue(); Op1v &= (1ULL << (8 << Class)) - 1;","",[Zero,cInt],[TESTrr32],[["DestReg","Op0Reg","Op0Reg"]]>;
// //def CMP_z_Long : // not supported
// def CMP_r_Byte : TargInstrSet<setcc,"","",[Regular,cByte],[CMPrr8],[["NullReg","Op0Reg","Op1Reg"]]>;
// def CMP_r_Short : TargInstrSet<setcc,"","",[Regular,cShort],[CMPrr16],[["NullReg","Op0Reg","Op1Reg"]]>;
// def CMP_r_Int : TargInstrSet<setcc,"","",[Regular,cInt],[CMPrr32],[["NullReg","Op0Reg","Op1Reg"]]>;
// //def CMP_r_Long : // two cases of long, depending on num of operands
// def CMP_r_FP : TargInstrSet<setcc,"","",[Regular,cFP],[FpUCOM,FNSTSWr8,SAHF],[["NullReg","Op0Reg","Op1Reg"],["NullReg"],["NullReg"]]>;
// def RET_NoOps : TargInstrSet<retrn,"","",[NoOps],[FP_REG_KILL,RET],[["NullReg"],["NullReg"]]>;
// def RET_Op_Byte : TargInstrSet<retrn,"promote32(X86::EAX, ValueRecord(Op0Reg, Op0Val->getType()));","",[Ops,cByte],[IMPLICIT_USE],[["NullReg","EAX","ESP"]]>;
// def RET_Op_Short : TargInstrSet<retrn,"promote32(X86::EAX, ValueRecord(Op0Reg, Op0Val->getType()));","",[Ops,cShort],[IMPLICIT_USE],[["NullReg","EAX","ESP"]]>;
// def RET_Op_Int : TargInstrSet<retrn,"promote32(X86::EAX, ValueRecord(Op0Reg, Op0Val->getType()));","",[Ops,cInt],[IMPLICIT_USE],[["NullReg","EAX","ESP"]]>;
// def RET_Op_FP : TargInstrSet<retrn,"","",[Ops,cFP],[FpSETRESULT,IMPLICIT_USE],[["NullReg","Op0Reg"],["NullReg","STO","ESP"]]>;
// def RET_Op_Long : TargInstrSet<retrn,"","",[Ops,cLong],[MOVrr32,MOVrr32,IMPLICIT_USE],[["EAX","Op0Reg"],["EDX","Op0Reg+1"],["NullReg","EAX","EDX","ESP"]]>;
// def BR_Uncond : TargInstrSet<branch,"","",[Uncond],[FP_REG_KILL,JMP],[["NullReg"],["NullReg","I.getSuccessor(0);"]]>;
// def BR_Cond_S_EQ :
// def BR_Cond_S_NE
// def BR_Cond_S_B
// def BR_Cond_S_AE
// def BR_Cond_S_A
// def BR_Cond_S_BE
// def BR_Cond_U_EQ
// def BR_Cond_U_NE
// def BR_Cond_U_LT
// def BR_Cond_U_GE
// def BR_Cond_U_GT
// def BR_Cond_U_LE
// def BR_Cond_U_S
// def BR_Cond_U_NS
// def CALL_Byte
// def CALL_Short
// def CALL_Int
// def CALL_Long
// def CALL_FP
def AND_Byte : TargInstrSet<logic_and,"","",[cByte],[ANDrr8],[["DestReg","Op0Reg","Op1Reg"]]>;
def AND_Short : TargInstrSet<logic_and,"","",[cShort],[ANDrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
def AND_Int : TargInstrSet<logic_and,"","",[cInt],[ANDrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
def AND_Long : TargInstrSet<logic_and,"","",[cLong],[ANDrr32,ANDrr32],[["DestReg","Op0Reg","Op1Reg"],["DestReg+1","Op0Reg+1","Op1Reg+1"]]>;
def OR_Byte : TargInstrSet<logic_or,"","",[cByte],[ORrr8],[["DestReg","Op0Reg","Op1Reg"]]>;
def OR_Short : TargInstrSet<logic_or,"","",[cShort],[ORrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
def OR_Int : TargInstrSet<logic_or,"","",[cInt],[ORrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
def OR_Long : TargInstrSet<logic_or,"","",[cLong],[ORrr32,ORrr32],[["DestReg","Op0Reg","Op1Reg"],["DestReg+1","Op0Reg+1","Op1Reg+1"]]>;
def XOR_NegOne_Byte : TargInstrSet<logic_xor,"","",[NegOne,cByte],[NOTr8],[["DestReg","Op0Reg"]]>;
def XOR_NegOne_Short: TargInstrSet<logic_xor,"","",[NegOne,cShort],[NOTr16],[["DestReg","Op0Reg"]]>;
def XOR_NegOne_Int : TargInstrSet<logic_xor,"","",[NegOne,cInt],[NOTr32],[["DestReg","Op0Reg"]]>;
//def XOR_NegOne_Long : // not supported (treat as regular long XOR)
def XOR_Other_Byte : TargInstrSet<logic_xor,"","",[Other,cByte],[XORrr8],[["DestReg","Op0Reg","Op1Reg"]]>;
def XOR_Other_Short : TargInstrSet<logic_xor,"","",[Other,cByte],[XORrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
def XOR_Other_Int : TargInstrSet<logic_xor,"","",[Other,cByte],[XORrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
def XOR_Other_Long : TargInstrSet<logic_xor,"","",[Other,cLong],[XORrr32,XORrr32],[["DestReg","Op0Reg","Op1Reg"],["DestReg+1","Op0Reg+1","Op1Reg+1"]]>;
// // TODO support for arbitrary values as operand arguments
// // or make ConstantInt versions as well-known variables
// // ConstantInt, unsigned Val
// def MUL_ConstTwo_Byte : TargInstrSet<mul,"ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1)); unsigned Val = (unsigned)CI->getRawValue(); unsigned Shift = ExactLog2(Val);","",[ConstTwo,cByte],[SHLir32],[["DestReg","Op0Reg","Shift-1"]]>;
// def MUL_ConstTwo_Short : TargInstrSet<mul,"ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1)); unsigned Val = (unsigned)CI->getRawValue(); unsigned Shift = ExactLog2(Val);","",[ConstTwo,cShort],[SHLir32],[["DestReg","Op0Reg","Shift-1"]]>;
// def MUL_ConstTwo_Int : TargInstrSet<mul,"ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1)); unsigned Val = (unsigned)CI->getRawValue(); unsigned Shift = ExactLog2(Val);","",[ConstTwo,cInt],[SHLir32],[["DestReg","Op0Reg","Shift-1"]]>;
// def MUL_ConstNotTwo_Byte : TargInstrSet<mul,"","",[ConstNotTwo,cByte],[CreateRegByte,MOVir8,MOVrr8,MULr8,MOVrr8],[["tmpReg"],["tmpReg","ConstRHS"],["AL","Op0Reg"],["NullReg","Op1Reg"],["DestReg","AL"]]>; //TODO fixme, define ConstRHS
// def MUL_ConstNotTwo_Short : TargInstrSet<mul,"","",[ConstNotTwo,cShort],[IMULri16],[["DestReg","Op0Reg","Val"]]>;
// def MUL_ConstNotTwo_Int : TargInstrSet<mul,"","",[ConstNotTwo,cInt],[IMULri32],[["DestReg","Op0Reg","Val"]]>;
// //def MUL_ConstNotTwo_Long :
// //def MUL_ConstNotTwo_FP :
// def MUL_Reg_Byte : TargInstrSet<mul,"","",[Reg,cByte],[MOVrr8,MULr8,MOVrr8],[["AL","Op0Reg"],["NullReg","Op1Reg"],["DestReg","AL"]]>;
// def MUL_Reg_Short : TargInstrSet<mul,"","",[Reg,cShort],[IMULrr16],[["DestReg","Op0Reg","Op1Reg"]]>;
// def MUL_Reg_Int : TargInstrSet<mul,"","",[Reg,cInt],[IMULrr32],[["DestReg","Op0Reg","Op1Reg"]]>;
// //def MUL_Reg_Long : // not supported (assert)
// def MUL_Reg_FP : TargInstrSet<mul,"","",[Reg,cFP],[FpMUL],[["DestReg","Op0Reg","Op1Reg"]]>;
// def STO_Byte
// def STO_Short
// def STO_Int
// def STO_FP
// def STO_Long
// DIVREM
// CAST
// PHI
// LOAD ARGS TO VIRTUAL REGS
// COPY CONSTANT
//TODO
// handling various operand options
// allowing for arbitrary code or operand arguments
// generate skeletons for selector function
//