public void CGenPrepareWord(Env env, CGenState state) {
// 1. Load lhs to EAX.
//
// regs:
// %eax = lhs
//
// stack:
// +-----+
// | ... | <- %esp
// +-----+
//
if (lhs.CGenValue(env, state) != Reg.EAX) {
throw new InvalidOperationException();
}
// 2. Push lhs to stack.
//
// regs:
// %eax = lhs
//
// stack:
// +-----+
// | ... |
// +-----+
// | lhs | <- %esp has decreased by 4
// +-----+
//
Int32 stack_size = state.CGenPushLong(Reg.EAX);
// 3. Load rhs to EAX.
//
// regs:
// %eax = rhs
//
// stack:
// +-----+
// | ... |
// +-----+
// | lhs | <- %esp
// +-----+
//
if (rhs.CGenValue(env, state) != Reg.EAX) {
throw new InvalidOperationException();
}
// 4. Move rhs into EBX. Pop lhs from stack, into EAX.
//
// regs:
// %eax = lhs
// %ebx = rhs
//
// stack:
// +-----+
// | ... | <- %esp has moved back.
// +-----+
//
state.MOVL(Reg.EAX, Reg.EBX);
state.CGenPopLong(stack_size, Reg.EAX);
}
public override Reg CGenValue(Env env, CGenState state)
{
Reg ret = expr.CGenValue(env, state);
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
state.NOT(Reg.EAX);
return Reg.EAX;
}
public void CGenTest(Env env, Reg ret, CGenState state) {
// test cond
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
break;
case Reg.ST0:
/// Compare expr with 0.0
/// < see cref = "BinaryArithmeticComp.OperateFloat(CGenState)" />
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
break;
default:
throw new InvalidProgramException();
}
}
public void CGenDecln(Env env, CGenState state) {
// .text
// [.globl <func>]
// <func>:
// pushl %ebp
// movl %esp, %ebp
//
state.TEXT();
Env.Entry entry = env.Find(name).Value;
state.COMMENT(ToString());
switch (entry.kind) {
case Env.EntryKind.GLOBAL:
switch (scs) {
case Decln.SCS.AUTO:
case Decln.SCS.EXTERN:
state.GLOBL(name);
break;
case Decln.SCS.STATIC:
// static definition
break;
default:
throw new InvalidOperationException();
}
break;
default:
throw new InvalidOperationException();
}
state.CGenFuncStart(name);
state.InFunction(GotoLabelsGrabber.GrabLabels(this.stmt));
stmt.CGenStmt(env, state);
state.CGenLabel(state.ReturnLabel);
state.OutFunction();
// leave
// ret
state.LEAVE();
state.RET();
state.NEWLINE();
}
public override Reg CGenValue(Env env, CGenState state) {
Reg ret = this.expr.CGenValue(env, state);
switch (this.kind) {
case Kind.DOUBLE_TO_FLOAT:
case Kind.FLOAT_TO_DOUBLE:
case Kind.PRESERVE_INT16:
case Kind.PRESERVE_INT8:
case Kind.NOP:
return ret;
case Kind.DOUBLE_TO_INT32:
case Kind.FLOAT_TO_INT32:
state.CGenConvertFloatToLong();
return Reg.EAX;
case Kind.INT32_TO_DOUBLE:
case Kind.INT32_TO_FLOAT:
state.CGenConvertLongToFloat();
return Reg.ST0;
case Kind.INT16_TO_INT32:
state.MOVSWL(Reg.AX, Reg.EAX);
return ret;
case Kind.INT8_TO_INT16:
case Kind.INT8_TO_INT32:
state.MOVSBL(Reg.AL, Reg.EAX);
return ret;
case Kind.UINT16_TO_UINT32:
state.MOVZWL(Reg.AX, Reg.EAX);
return ret;
case Kind.UINT8_TO_UINT16:
case Kind.UINT8_TO_UINT32:
state.MOVZBL(Reg.AL, Reg.EAX);
return ret;
default:
throw new InvalidProgramException();
}
}
public override Reg CGenValue(Env env, CGenState state)
{
Reg ret = expr.CGenValue(env, state);
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
if (expr.type.kind != ExprType.Kind.POINTER) {
throw new InvalidProgramException();
}
ExprType type = ((TPointer)expr.type).ref_t;
switch (type.kind) {
case ExprType.Kind.ARRAY:
case ExprType.Kind.FUNCTION:
return Reg.EAX;
case ExprType.Kind.CHAR:
state.MOVSBL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.UCHAR:
state.MOVZBL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.SHORT:
state.MOVSWL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.USHORT:
state.MOVZWL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
state.MOVL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FLOAT:
state.FLDS(0, Reg.EAX);
return Reg.ST0;
case ExprType.Kind.DOUBLE:
state.FLDL(0, Reg.EAX);
return Reg.ST0;
case ExprType.Kind.STRUCT_OR_UNION:
//// %esi = src address
//state.MOVL(Reg.EAX, Reg.ESI);
//// %edi = dst address
//state.CGenExpandStackBy(Utils.RoundUp(type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI);
//// %ecx = nbytes
//state.MOVL(type.SizeOf, Reg.ECX);
//state.CGenMemCpy();
//return Reg.STACK;
return Reg.EAX;
case ExprType.Kind.VOID:
default:
throw new InvalidProgramException();
}
}
public override void CGenAddress(Env env, CGenState state)
{
Reg ret = expr.CGenValue(env, state);
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
}
public override void CGenStmt(Env env, CGenState state) {
Reg ret = CGenExprStmt(env, cond, state);
CGenTest(env, ret, state);
Int32 false_label = state.RequestLabel();
Int32 finish_label = state.RequestLabel();
state.JZ(false_label);
true_stmt.CGenStmt(env, state);
state.JMP(finish_label);
state.CGenLabel(false_label);
false_stmt.CGenStmt(env, state);
state.CGenLabel(finish_label);
}
public override Reg CGenValue(Env env, CGenState state)
{
Env.Entry entry = env.Find(name).Value;
Int32 offset = entry.offset;
//if (entry.kind == Env.EntryKind.STACK) {
// offset = -offset;
//}
switch (entry.kind) {
case Env.EntryKind.ENUM:
// 1. If the variable is an enum constant,
// return the value in %eax.
state.MOVL(offset, Reg.EAX);
return Reg.EAX;
case Env.EntryKind.FRAME:
case Env.EntryKind.STACK:
// 2. If the variable is a function argument or a local variable,
// the address would be offset(%ebp).
switch (type.kind) {
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
// %eax = offset(%ebp)
state.MOVL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FLOAT:
// %st(0) = offset(%ebp)
state.FLDS(offset, Reg.EBP);
return Reg.ST0;
case ExprType.Kind.DOUBLE:
// %st(0) = offset(%ebp)
state.FLDL(offset, Reg.EBP);
return Reg.ST0;
case ExprType.Kind.STRUCT_OR_UNION:
// %eax = address
state.LEA(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
//state.LEA(offset, Reg.EBP, Reg.ESI); // source address
//state.CGenExpandStackBy(Utils.RoundUp(type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI); // destination address
//state.MOVL(type.SizeOf, Reg.ECX); // nbytes
//state.CGenMemCpy();
//return Reg.STACK;
case ExprType.Kind.VOID:
throw new InvalidProgramException("How could a variable be void?");
// %eax = $0
// state.MOVL(0, Reg.EAX);
// return Reg.EAX;
case ExprType.Kind.FUNCTION:
throw new InvalidProgramException("How could a variable be a function designator?");
// %eax = function_name
// state.MOVL(name, Reg.EAX);
// return Reg.EAX;
case ExprType.Kind.CHAR:
// %eax = [char -> long](off(%ebp))
state.MOVSBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.UCHAR:
// %eax = [uchar -> ulong](off(%ebp))
state.MOVZBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.SHORT:
// %eax = [short -> long](off(%ebp))
state.MOVSWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.USHORT:
// %eax = [ushort -> ulong](off(%ebp))
state.MOVZWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.ARRAY:
// %eax = (off(%ebp))
state.LEA(offset, Reg.EBP, Reg.EAX); // source address
return Reg.EAX;
default:
throw new InvalidOperationException($"Cannot get value of {type.kind}");
}
case Env.EntryKind.GLOBAL:
switch (type.kind) {
case ExprType.Kind.CHAR:
state.MOVSBL(name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.UCHAR:
state.MOVZBL(name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.SHORT:
state.MOVSWL(name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.USHORT:
state.MOVZWL(name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
state.MOVL(name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FUNCTION:
state.MOVL("$" + name, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FLOAT:
state.FLDS(name);
return Reg.ST0;
case ExprType.Kind.DOUBLE:
state.FLDL(name);
return Reg.ST0;
case ExprType.Kind.STRUCT_OR_UNION:
state.MOVL($"${name}", Reg.EAX);
return Reg.EAX;
//state.LEA(name, Reg.ESI); // source address
//state.CGenExpandStackBy(Utils.RoundUp(type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI); // destination address
//state.MOVL(type.SizeOf, Reg.ECX); // nbytes
//state.CGenMemCpy();
//return Reg.STACK;
case ExprType.Kind.VOID:
throw new InvalidProgramException("How could a variable be void?");
//state.MOVL(0, Reg.EAX);
//return Reg.EAX;
case ExprType.Kind.ARRAY:
state.MOVL($"${name}", Reg.EAX);
return Reg.EAX;
default:
throw new InvalidProgramException("cannot get the value of a " + type.kind.ToString());
}
case Env.EntryKind.TYPEDEF:
default:
throw new InvalidProgramException("cannot get the value of a " + entry.kind.ToString());
}
}
public Variable(ExprType type, String name, Env env)
: base(type)
{
this.name = name;
this.Env = env;
}
public override Reg CGenValue(Env env, CGenState state)
{
// GCC's IA-32 calling convention
// Caller is responsible to push all arguments to the stack in reverse order.
// Each argument is at least aligned to 4 bytes - even a char would take 4 bytes.
// The return value is stored in %eax, or %st(0), if it is a scalar.
//
// The stack would look like this after pushing all the arguments:
// +--------+
// | .... |
// +--------+
// | argn |
// +--------+
// | .... |
// +--------+
// | arg2 |
// +--------+
// | arg1 |
// +--------+ <- %esp before call
//
// Things are different with structs and unions.
// Since structs may not fit in 4 bytes, it has to be returned in memory.
// Caller allocates a chunk of memory for the struct and push the address of it as an extra argument.
// Callee returns %eax with that address.
//
// The stack would look like this after pushing all the arguments:
// +--------+
// +--> | struct | <- struct should be returned here.
// | +--------+
// | | argn |
// | +--------+
// | | .... |
// | +--------+
// | | arg2 |
// | +--------+
// | | arg1 |
// | +--------+
// +----| addr | <- %esp before call
// +--------+
//
state.NEWLINE();
state.COMMENT($"Before pushing the arguments, stack size = {state.StackSize}.");
var r_pack = Utils.PackArguments(args.Select(_ => _.type).ToList());
Int32 pack_size = r_pack.Item1;
IReadOnlyList<Int32> offsets = r_pack.Item2;
if (type is TStructOrUnion) {
// If the function returns a struct
// Allocate space for return value.
state.COMMENT("Allocate space for returning stack.");
state.CGenExpandStackWithAlignment(type.SizeOf, type.Alignment);
// Temporarily store the address in %eax.
state.MOVL(Reg.ESP, Reg.EAX);
// add an extra argument and move all other arguments upwards.
pack_size += ExprType.SIZEOF_POINTER;
offsets = offsets.Select(_ => _ + ExprType.SIZEOF_POINTER).ToList();
}
// Allocate space for arguments.
// If returning struct, the extra pointer is included.
state.COMMENT($"Arguments take {pack_size} bytes.");
state.CGenExpandStackBy(pack_size);
state.NEWLINE();
// Store the address as the first argument.
if (type is TStructOrUnion) {
state.COMMENT("Putting extra argument for struct return address.");
state.MOVL(Reg.EAX, 0, Reg.ESP);
state.NEWLINE();
}
// This is the stack size before calling the function.
Int32 header_base = -state.StackSize;
// Push the arguments onto the stack in reverse order
for (Int32 i = args.Count; i-- > 0;) {
Expr arg = args[i];
Int32 pos = header_base + offsets[i];
state.COMMENT($"Argument {i} is at {pos}");
Reg ret = arg.CGenValue(env, state);
switch (arg.type.kind) {
case ExprType.Kind.ARRAY:
case ExprType.Kind.CHAR:
case ExprType.Kind.UCHAR:
case ExprType.Kind.SHORT:
case ExprType.Kind.USHORT:
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
state.MOVL(Reg.EAX, pos, Reg.EBP);
break;
case ExprType.Kind.DOUBLE:
if (ret != Reg.ST0) {
throw new InvalidProgramException();
}
state.FSTPL(pos, Reg.EBP);
break;
case ExprType.Kind.FLOAT:
if (ret != Reg.ST0) {
throw new InvalidProgramException();
}
state.FSTPL(pos, Reg.EBP);
break;
case ExprType.Kind.STRUCT_OR_UNION:
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
state.MOVL(Reg.EAX, Reg.ESI);
state.LEA(pos, Reg.EBP, Reg.EDI);
state.MOVL(arg.type.SizeOf, Reg.ECX);
state.CGenMemCpy();
break;
default:
throw new InvalidProgramException();
}
state.NEWLINE();
}
// When evaluating arguments, the stack might be changed.
// We must restore the stack.
state.CGenForceStackSizeTo(-header_base);
// Get function address
if (func.type is TFunction) {
func.CGenAddress(env, state);
} else if (func.type is TPointer) {
func.CGenValue(env, state);
} else {
throw new InvalidProgramException();
}
state.CALL("*%eax");
state.COMMENT("Function returned.");
state.NEWLINE();
if (type.kind == ExprType.Kind.FLOAT || type.kind == ExprType.Kind.DOUBLE) {
return Reg.ST0;
} else {
return Reg.EAX;
}
}
public abstract Reg CGenValue(Env env, CGenState state);
// MakeCast
// ========
// input: expr, type
// output: TypeCast
// converts expr to type
//
public static Expr MakeCast(Expr expr, ExprType type, Env env) {
// if two types are equal, return expr
if (EqualType(expr.type, type)) {
return expr;
}
// from pointer
if (expr.type.kind == ExprType.Kind.POINTER) {
return FromPointer(expr, type, env);
}
// to pointer
if (type.kind == ExprType.Kind.POINTER) {
return ToPointer(expr, type, env);
}
switch (expr.type.kind) {
// from signed integral
case ExprType.Kind.CHAR:
case ExprType.Kind.SHORT:
case ExprType.Kind.LONG:
return SignedIntegralToArith(expr, type);
// from unsigned integral
case ExprType.Kind.UCHAR:
case ExprType.Kind.USHORT:
case ExprType.Kind.ULONG:
return UnsignedIntegralToArith(expr, type);
// from float
case ExprType.Kind.FLOAT:
case ExprType.Kind.DOUBLE:
return FloatToArith(expr, type);
case ExprType.Kind.VOID:
case ExprType.Kind.POINTER:
case ExprType.Kind.FUNCTION:
case ExprType.Kind.ARRAY:
case ExprType.Kind.INCOMPLETE_ARRAY:
case ExprType.Kind.STRUCT_OR_UNION:
default:
throw new InvalidOperationException("Error: expression type not supported for casting from.");
}
}
/// <summary>
/// From:
/// pointer, integral
/// To:
/// pointer
/// </summary>
public static Expr ToPointer(Expr expr, ExprType type, Env env) {
ExprType.Kind from = expr.type.kind;
ExprType.Kind to = type.kind;
if (to != ExprType.Kind.POINTER) {
throw new InvalidOperationException("Error: expected casting to pointer.");
}
if (from == ExprType.Kind.POINTER) {
if (expr.IsConstExpr) {
return new ConstPtr(((ConstPtr)expr).value, type, env);
} else {
return new TypeCast(Kind.NOP, expr, type, env);
}
}
if (expr.type.IsIntegral) {
// if we are casting from an integral
// whatever integral -> ulong
switch (expr.type.kind) {
case ExprType.Kind.CHAR:
case ExprType.Kind.SHORT:
case ExprType.Kind.LONG:
expr = SignedIntegralToArith(expr, new TULong(type.is_const, type.is_volatile));
break;
case ExprType.Kind.UCHAR:
case ExprType.Kind.USHORT:
case ExprType.Kind.ULONG:
expr = UnsignedIntegralToArith(expr, new TULong(type.is_const, type.is_volatile));
break;
default:
break;
}
// ulong -> pointer
if (expr.IsConstExpr) {
return new ConstPtr(((ConstULong)expr).value, type, env);
} else {
return new TypeCast(Kind.NOP, expr, type, env);
}
} else if (expr.type is TFunction) {
if (!expr.type.EqualType((type as TPointer).ref_t)) {
throw new InvalidOperationException("Casting from an incompatible function.");
}
// TODO: only allow compatible type?
return new TypeCast(Kind.NOP, expr, type, env);
} else if (expr.type is TArray) {
// TODO: allow any pointer type to cast to?
return new TypeCast(Kind.NOP, expr, type, env);
}
throw new InvalidOperationException("Error: casting from an unsupported type to pointer.");
}
/// <summary>
/// From:
/// pointer
/// To:
/// pointer, integral
/// </summary>
public static Expr FromPointer(Expr expr, ExprType type, Env env) {
ExprType.Kind from = expr.type.kind;
ExprType.Kind to = type.kind;
if (from != ExprType.Kind.POINTER) {
throw new InvalidOperationException("Expected a pointer.");
}
// if we are casting to another pointer, do a nop
if (to == ExprType.Kind.POINTER) {
if (expr.IsConstExpr) {
return new ConstPtr(((ConstPtr)expr).value, type, env);
} else {
return new TypeCast(Kind.NOP, expr, type, env);
}
}
// if we are casting to an integral
if (type.IsIntegral) {
// pointer -> ulong -> whatever integral
if (expr.IsConstExpr) {
expr = new ConstULong(((ConstPtr)expr).value, env);
} else {
expr = new TypeCast(Kind.NOP, expr, new TULong(type.is_const, type.is_volatile), env);
}
return MakeCast(expr, type, env);
}
throw new InvalidOperationException("Casting from a pointer to an unsupported type.");
}
public TypeCast(Kind kind, Expr expr, ExprType type, Env env)
: base(type) {
this.expr = expr;
this.kind = kind;
this.Env = env;
}
public override void CGenStmt(Env env, CGenState state) {
state.CGenLabel(state.GotoLabel(this.label));
state.CGenForceStackSizeTo(state.StackSize);
this.stmt.CGenStmt(env, state);
}
public override void CGenStmt(Env env, CGenState state) {
Int32 label = state.GotoLabel(this.label);
state.JMP(label);
}
public virtual void CGenAddress(Env env, CGenState state)
{
throw new NotImplementedException();
}
public override Reg CGenValue(Env env, CGenState state)
{
Reg reg = Reg.EAX;
foreach (Expr expr in exprs) {
reg = expr.CGenValue(env, state);
}
return reg;
}
public virtual void CGenPush(Env env, CGenState state)
{
Reg ret = CGenValue(env, state);
switch (type.kind) {
case ExprType.Kind.CHAR:
case ExprType.Kind.UCHAR:
case ExprType.Kind.SHORT:
case ExprType.Kind.USHORT:
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
// Integral
if (ret != Reg.EAX) {
throw new InvalidProgramException("Integral values should be returned to %eax");
}
state.CGenPushLong(Reg.EAX);
break;
case ExprType.Kind.FLOAT:
// Float
if (ret != Reg.ST0) {
throw new InvalidProgramException("Floats should be returned to %st(0)");
}
state.CGenExpandStackBy4Bytes();
state.FSTS(0, Reg.ESP);
break;
case ExprType.Kind.DOUBLE:
// Double
if (ret != Reg.ST0) {
throw new InvalidProgramException("Doubles should be returned to %st(0)");
}
state.CGenExpandStackBy8Bytes();
state.FSTL(0, Reg.ESP);
break;
case ExprType.Kind.ARRAY:
case ExprType.Kind.FUNCTION:
case ExprType.Kind.POINTER:
// Pointer
if (ret != Reg.EAX) {
throw new InvalidProgramException("Pointer values should be returned to %eax");
}
state.CGenPushLong(Reg.EAX);
break;
case ExprType.Kind.INCOMPLETE_ARRAY:
case ExprType.Kind.VOID:
throw new InvalidProgramException(type.kind.ToString() + " can't be pushed onto the stack");
case ExprType.Kind.STRUCT_OR_UNION:
throw new NotImplementedException();
}
}
public override void CGenAddress(Env env, CGenState state)
{
if (expr.type.kind != ExprType.Kind.STRUCT_OR_UNION) {
throw new InvalidProgramException();
}
// %eax = address of struct or union
expr.CGenAddress(env, state);
// offset inside the pack
Int32 offset = ((TStructOrUnion)expr.type)
.Attribs
.First(_ => _.name == name)
.offset;
state.ADDL(offset, Reg.EAX);
}
public override void CGenAddress(Env env, CGenState state)
{
throw new Exception("Error: cannot get the address of a function call.");
}
public override void CGenStmt(Env env, CGenState state) {
Int32 label = state.CaseLabel(value);
state.CGenLabel(label);
stmt.CGenStmt(env, state);
}
public override Reg CGenValue(Env env, CGenState state)
{
expr.CGenAddress(env, state);
return Reg.EAX;
}
//
// test cond
// jz false ---+
// true_expr |
// +------- jmp finish |
// | false: <--------+
// | false_expr
// +--> finish:
//
public override Reg CGenValue(Env env, CGenState state)
{
Int32 stack_size = state.StackSize;
Reg ret = cond.CGenValue(env, state);
state.CGenForceStackSizeTo(stack_size);
// test cond
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
break;
case Reg.ST0:
/// Compare expr with 0.0
/// < see cref = "BinaryArithmeticComp.OperateFloat(CGenState)" />
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
break;
default:
throw new InvalidProgramException();
}
Int32 false_label = state.RequestLabel();
Int32 finish_label = state.RequestLabel();
state.JZ(false_label);
true_expr.CGenValue(env, state);
state.JMP(finish_label);
state.CGenLabel(false_label);
ret = false_expr.CGenValue(env, state);
state.CGenLabel(finish_label);
return ret;
}
public override void CGenAddress(Env env, CGenState state)
{
Env.Entry entry = env.Find(name).Value;
Int32 offset = entry.offset;
switch (entry.kind) {
case Env.EntryKind.FRAME:
case Env.EntryKind.STACK:
state.LEA(offset, Reg.EBP, Reg.EAX);
return;
case Env.EntryKind.GLOBAL:
state.LEA(name, Reg.EAX);
return;
case Env.EntryKind.ENUM:
case Env.EntryKind.TYPEDEF:
default:
throw new InvalidProgramException("cannot get the address of " + entry.kind);
}
}
public override Reg CGenValue(Env env, CGenState state)
{
// 1. %eax = &lhs
lvalue.CGenAddress(env, state);
// 2. push %eax
Int32 pos = state.CGenPushLong(Reg.EAX);
Reg ret = rvalue.CGenValue(env, state);
switch (lvalue.type.kind) {
case ExprType.Kind.CHAR:
case ExprType.Kind.UCHAR:
// pop %ebx
// now %ebx = %lhs
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVB(Reg.AL, 0, Reg.EBX);
return Reg.EAX;
case ExprType.Kind.SHORT:
case ExprType.Kind.USHORT:
// pop %ebx
// now %ebx = %lhs
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVW(Reg.AX, 0, Reg.EBX);
return Reg.EAX;
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
// pop %ebx
// now %ebx = &lhs
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVL(Reg.EAX, 0, Reg.EBX);
return Reg.EAX;
case ExprType.Kind.FLOAT:
// pop %ebx
// now %ebx = &lhs
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %st(0)
state.FSTS(0, Reg.EBX);
return Reg.ST0;
case ExprType.Kind.DOUBLE:
// pop %ebx
// now %ebx = &lhs
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %st(0)
state.FSTL(0, Reg.EBX);
return Reg.ST0;
case ExprType.Kind.STRUCT_OR_UNION:
// pop %edi
// now %edi = &lhs
state.CGenPopLong(pos, Reg.EDI);
// %esi = &rhs
state.MOVL(Reg.EAX, Reg.ESI);
// %ecx = nbytes
state.MOVL(lvalue.type.SizeOf, Reg.ECX);
state.CGenMemCpy();
// %eax = &lhs
state.MOVL(Reg.EDI, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FUNCTION:
case ExprType.Kind.VOID:
case ExprType.Kind.ARRAY:
case ExprType.Kind.INCOMPLETE_ARRAY:
default:
throw new InvalidProgramException("cannot assign to a " + type.kind.ToString());
}
}
public override Reg CGenValue(Env env, CGenState state)
{
// %eax is the address of the struct/union
if (expr.CGenValue(env, state) != Reg.EAX) {
throw new InvalidProgramException();
}
if (expr.type.kind != ExprType.Kind.STRUCT_OR_UNION) {
throw new InvalidProgramException();
}
// size of the struct or union
Int32 struct_size = expr.type.SizeOf;
// offset inside the pack
Int32 attrib_offset = ((TStructOrUnion)expr.type)
.Attribs
.First(_ => _.name == name)
.offset;
// can't be a function designator.
switch (type.kind) {
case ExprType.Kind.ARRAY:
case ExprType.Kind.STRUCT_OR_UNION:
state.ADDL(attrib_offset, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.CHAR:
state.MOVSBL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.UCHAR:
state.MOVZBL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.SHORT:
state.MOVSWL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.USHORT:
state.MOVZWL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.LONG:
case ExprType.Kind.ULONG:
case ExprType.Kind.POINTER:
state.MOVL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprType.Kind.FLOAT:
state.FLDS(attrib_offset, Reg.EAX);
return Reg.ST0;
case ExprType.Kind.DOUBLE:
state.FLDL(attrib_offset, Reg.EAX);
return Reg.ST0;
default:
throw new InvalidProgramException();
}
}
public override void CGenStmt(Env env, CGenState state) {
Int32 label = state.DefaultLabel;
state.CGenLabel(label);
stmt.CGenStmt(env, state);
}
