|
public MOVL ( |
||
| imm | ||
| dst | System.Reg | |
| return | void | |
// %eax = left, %ebx = right, stack unchanged
private void CGenPrepareIntegralOperands(CGenState state) {
// 1. Load Left to EAX.
//
// regs:
// %eax = Left
//
// stack:
// +-----+
// | ... | <- %esp
// +-----+
//
if (this.Left.CGenValue(state) != Reg.EAX) {
throw new InvalidOperationException();
}
// 2. Push Left to stack.
//
// regs:
// %eax = Left
//
// stack:
// +-----+
// | ... |
// +-----+
// | Left | <- %esp has decreased by 4
// +-----+
//
Int32 stack_size = state.CGenPushLong(Reg.EAX);
// 3. Load Right to EAX.
//
// regs:
// %eax = Right
//
// stack:
// +-----+
// | ... |
// +-----+
// | Left | <- %esp
// +-----+
//
if (this.Right.CGenValue(state) != Reg.EAX) {
throw new InvalidOperationException();
}
// 4. Move Right into EBX. Pop Left from stack, into EAX.
//
// regs:
// %eax = Left
// %ebx = Right
//
// stack:
// +-----+
// | ... | <- %esp has moved back.
// +-----+
//
state.MOVL(Reg.EAX, Reg.EBX);
state.CGenPopLong(stack_size, Reg.EAX);
}
public override Reg CGenValue(CGenState state) {
state.MOVL((Int32)this.Value, Reg.EAX);
return Reg.EAX;
}
// * function;
// * extern function;
// * static function;
// * obj;
// * obj = Init;
// * static obj;
// * static obj = Init;
// * extern obj;
// * extern obj = Init;
public void CGenDecln(Env env, CGenState state) {
if (env.IsGlobal()) {
if (this.initr.IsSome) {
Initr initr = this.initr.Value;
switch (this.scs) {
case StorageClass.AUTO:
state.GLOBL(this.name);
break;
case StorageClass.EXTERN:
throw new InvalidProgramException();
case StorageClass.STATIC:
break;
case StorageClass.TYPEDEF:
// Ignore.
return;
default:
throw new InvalidProgramException();
}
state.DATA();
state.ALIGN(ExprType.ALIGN_LONG);
state.CGenLabel(this.name);
Int32 last = 0;
initr.Iterate(this.type, (Int32 offset, Expr expr) => {
if (offset > last) {
state.ZERO(offset - last);
}
if (!expr.IsConstExpr) {
throw new InvalidOperationException("Cannot initialize with non-const expression.");
}
switch (expr.Type.Kind) {
// TODO: without const char/short, how do I initialize?
case ExprTypeKind.CHAR:
case ExprTypeKind.UCHAR:
case ExprTypeKind.SHORT:
case ExprTypeKind.USHORT:
throw new NotImplementedException();
case ExprTypeKind.LONG:
state.LONG(((ConstLong)expr).Value);
break;
case ExprTypeKind.ULONG:
state.LONG((Int32)((ConstULong)expr).Value);
break;
case ExprTypeKind.POINTER:
state.LONG((Int32)((ConstPtr)expr).Value);
break;
case ExprTypeKind.FLOAT:
byte[] float_bytes = BitConverter.GetBytes(((ConstFloat)expr).Value);
Int32 intval = BitConverter.ToInt32(float_bytes, 0);
state.LONG(intval);
break;
case ExprTypeKind.DOUBLE:
byte[] double_bytes = BitConverter.GetBytes(((ConstDouble)expr).Value);
Int32 first_int = BitConverter.ToInt32(double_bytes, 0);
Int32 second_int = BitConverter.ToInt32(double_bytes, 4);
state.LONG(first_int);
state.LONG(second_int);
break;
default:
throw new InvalidProgramException();
}
last = offset + expr.Type.SizeOf;
});
} else {
// Global without initialization.
switch (this.scs) {
case StorageClass.AUTO:
// .comm name,size,align
break;
case StorageClass.EXTERN:
break;
case StorageClass.STATIC:
// .local name
// .comm name,size,align
state.LOCAL(this.name);
break;
case StorageClass.TYPEDEF:
// Ignore.
return;
default:
throw new InvalidProgramException();
}
if (this.type.Kind != ExprTypeKind.FUNCTION) {
state.COMM(this.name, this.type.SizeOf, ExprType.ALIGN_LONG);
}
}
state.NEWLINE();
} else {
// stack object
state.CGenExpandStackTo(env.StackSize, ToString());
Int32 stack_size = env.StackSize;
// pos should be equal to stack_size, but whatever...
Int32 pos = env.Find(this.name).Value.Offset;
if (this.initr.IsNone) {
return;
}
Initr initr = this.initr.Value;
initr.Iterate(this.type, (Int32 offset, Expr expr) => {
Reg ret = expr.CGenValue(state);
switch (expr.Type.Kind) {
case ExprTypeKind.CHAR:
case ExprTypeKind.UCHAR:
state.MOVB(Reg.EAX, pos + offset, Reg.EBP);
break;
case ExprTypeKind.SHORT:
case ExprTypeKind.USHORT:
state.MOVW(Reg.EAX, pos + offset, Reg.EBP);
break;
case ExprTypeKind.DOUBLE:
state.FSTPL(pos + offset, Reg.EBP);
break;
case ExprTypeKind.FLOAT:
state.FSTPS(pos + offset, Reg.EBP);
break;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
state.MOVL(Reg.EAX, pos + offset, Reg.EBP);
break;
case ExprTypeKind.STRUCT_OR_UNION:
state.MOVL(Reg.EAX, Reg.ESI);
state.LEA(pos + offset, Reg.EBP, Reg.EDI);
state.MOVL(expr.Type.SizeOf, Reg.ECX);
state.CGenMemCpy();
break;
case ExprTypeKind.ARRAY:
case ExprTypeKind.FUNCTION:
throw new InvalidProgramException($"How could a {expr.Type.Kind} be in a init list?");
default:
throw new InvalidProgramException();
}
state.CGenForceStackSizeTo(stack_size);
});
} // stack object
}
public override sealed Reg CGenValue(CGenState state) {
// 1. Get the address of expr.
//
// regs:
// %eax = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
this.Expr.CGenAddress(state);
// 2. Push address.
//
// regs:
// %eax = &expr
//
// stack:
// +-------+
// | ..... |
// +-------+
// | &expr | <- %esp
// +-------+
//
Int32 stack_size = state.CGenPushLong(Reg.EAX);
// 3. Get current Value of expr.
//
// 1) If expr is an integral or pointer:
//
// regs:
// %eax = expr
//
// stack:
// +-------+
// | ..... |
// +-------+
// | &expr | <- %esp
// +-------+
//
//
// 2) If expr is a float:
//
// regs:
// %eax = &expr
//
// stack:
// +-------+
// | ..... |
// +-------+
// | &expr | <- %esp
// +-------+
//
// float stack:
// +-------+
// | expr | <- %st(0)
// +-------+
//
Reg ret = this.Expr.CGenValue(state);
switch (ret) {
case Reg.EAX:
// expr is an integral or pointer.
// 4. Pop address to %ecx.
//
// regs:
// %eax = expr
// %ecx = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
state.CGenPopLong(stack_size, Reg.ECX);
// 5. Cache current Value of Expr in %ebx.
//
// regs:
// %eax = expr
// %ebx = expr
// %ecx = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
state.MOVL(Reg.EAX, Reg.EBX);
// 6. Calculate the new value in %ebx or %eax and save.
// Set %eax to be the return Value.
//
// regs:
// %eax = expr or (expr +- 1)
// %ebx = (expr +- 1) or expr
// %ecx = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
switch (this.Expr.Type.Kind) {
case ExprTypeKind.CHAR:
case ExprTypeKind.UCHAR:
CalcAndSaveByte(state);
return Reg.EAX;
case ExprTypeKind.SHORT:
case ExprTypeKind.USHORT:
CalcAndSaveWord(state);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
CalcAndSaveByte(state);
return Reg.EAX;
case ExprTypeKind.POINTER:
CalcAndSavePtr(state);
return Reg.EAX;
default:
throw new InvalidProgramException();
}
case Reg.ST0:
// Expr is a float.
// 4. Pop address to %ecx.
//
// regs:
// %ecx = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
state.CGenPopLong(stack_size, Reg.ECX);
// 5. Load 1.0 to FPU stack.
//
// regs:
// %ecx = &expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
// float stack:
// +-------+
// | expr | <- %st(1)
// +-------+
// | 1.0 | <- %st(0)
// +-------+
//
state.FLD1();
// 6. Calculate the new value and save back.
// Set %st(0) to be the new or original Value.
//
// regs:
// %ecx = &Expr
//
// stack:
// +-------+
// | ..... | <- %esp
// +-------+
//
// float stack:
// +---------------------+
// | expr or (epxr +- 1) | <- %st(0)
// +---------------------+
//
switch (this.Expr.Type.Kind) {
case ExprTypeKind.FLOAT:
CalcAndSaveFloat(state);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
CalcAndSaveDouble(state);
return Reg.ST0;
default:
throw new InvalidProgramException();
}
default:
throw new InvalidProgramException();
}
}
public override void CalcAndSavePtr(CGenState state) {
state.SUBL(this.Expr.Type.SizeOf, Reg.EAX);
state.MOVL(Reg.EAX, 0, Reg.ECX);
}
public override void CalcAndSaveLong(CGenState state) {
state.SUBL(1, Reg.EAX);
state.MOVL(Reg.EAX, 0, Reg.ECX);
}
public override Reg CGenValue(CGenState state) {
Reg ret = this.Expr.CGenValue(state);
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
if (this.Expr.Type.Kind != ExprTypeKind.POINTER) {
throw new InvalidProgramException();
}
ExprType type = ((PointerType)this.Expr.Type).RefType;
switch (type.Kind) {
case ExprTypeKind.ARRAY:
case ExprTypeKind.FUNCTION:
return Reg.EAX;
case ExprTypeKind.CHAR:
state.MOVSBL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
state.MOVZBL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
state.MOVSWL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
state.MOVZWL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
state.MOVL(0, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
state.FLDS(0, Reg.EAX);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
state.FLDL(0, Reg.EAX);
return Reg.ST0;
case ExprTypeKind.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 ExprTypeKind.VOID:
default:
throw new InvalidProgramException();
}
}
public override Reg CGenValue(CGenState state) {
// %eax is the address of the struct/union
if (this.Expr.CGenValue(state) != Reg.EAX) {
throw new InvalidProgramException();
}
if (this.Expr.Type.Kind != ExprTypeKind.STRUCT_OR_UNION) {
throw new InvalidProgramException();
}
// size of the struct or union
Int32 struct_size = this.Expr.Type.SizeOf;
// offset inside the pack
Int32 attrib_offset = ((StructOrUnionType)this.Expr.Type)
.Attribs
.First(_ => _.name == this.Name)
.offset;
// can't be a function designator.
switch (this.Type.Kind) {
case ExprTypeKind.ARRAY:
case ExprTypeKind.STRUCT_OR_UNION:
state.ADDL(attrib_offset, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.CHAR:
state.MOVSBL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
state.MOVZBL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
state.MOVSWL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
state.MOVZWL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
state.MOVL(attrib_offset, Reg.EAX, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
state.FLDS(attrib_offset, Reg.EAX);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
state.FLDL(attrib_offset, Reg.EAX);
return Reg.ST0;
default:
throw new InvalidProgramException();
}
}
public override Reg CGenValue(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(this.Args.Select(_ => _.Type).ToList());
Int32 pack_size = r_pack.Item1;
IReadOnlyList<Int32> offsets = r_pack.Item2;
if (this.Type is StructOrUnionType) {
// If the function returns a struct
// Allocate space for return Value.
state.COMMENT("Allocate space for returning stack.");
state.CGenExpandStackWithAlignment(this.Type.SizeOf, this.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($"Arguments take {pack_size} bytes.");
state.CGenExpandStackBy(pack_size);
state.NEWLINE();
// Store the address as the first argument.
if (this.Type is StructOrUnionType) {
state.COMMENT("Putting extra argument for struct return address.");
state.MOVL(Reg.EAX, 0, Reg.ESP);
state.NEWLINE();
}
// This is the stack size before calling the function.
Int32 header_base = -state.StackSize;
// Push the arguments onto the stack in reverse order
for (Int32 i = this.Args.Count; i-- > 0;) {
Expr arg = this.Args[i];
Int32 pos = header_base + offsets[i];
state.COMMENT($"Argument {i} is at {pos}");
Reg ret = arg.CGenValue(state);
switch (arg.Type.Kind) {
case ExprTypeKind.ARRAY:
case ExprTypeKind.CHAR:
case ExprTypeKind.UCHAR:
case ExprTypeKind.SHORT:
case ExprTypeKind.USHORT:
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
if (ret != Reg.EAX) {
throw new InvalidProgramException();
}
state.MOVL(Reg.EAX, pos, Reg.EBP);
break;
case ExprTypeKind.DOUBLE:
if (ret != Reg.ST0) {
throw new InvalidProgramException();
}
state.FSTPL(pos, Reg.EBP);
break;
case ExprTypeKind.FLOAT:
if (ret != Reg.ST0) {
throw new InvalidProgramException();
}
state.FSTPL(pos, Reg.EBP);
break;
case ExprTypeKind.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 (this.Func.Type is FunctionType) {
this.Func.CGenAddress(state);
} else if (this.Func.Type is PointerType) {
this.Func.CGenValue(state);
} else {
throw new InvalidProgramException();
}
state.CALL("*%eax");
state.COMMENT("Function returned.");
state.NEWLINE();
if (this.Type.Kind == ExprTypeKind.FLOAT || this.Type.Kind == ExprTypeKind.DOUBLE) {
return Reg.ST0;
}
return Reg.EAX;
}
public override Reg CGenValue(CGenState state) {
Env.Entry entry = this.Env.Find(this.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 (this.Type.Kind) {
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
// %eax = offset(%ebp)
state.MOVL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
// %st(0) = offset(%ebp)
state.FLDS(offset, Reg.EBP);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
// %st(0) = offset(%ebp)
state.FLDL(offset, Reg.EBP);
return Reg.ST0;
case ExprTypeKind.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 ExprTypeKind.VOID:
throw new InvalidProgramException("How could a variable be void?");
// %eax = $0
// state.MOVL(0, Reg.EAX);
// return Reg.EAX;
case ExprTypeKind.FUNCTION:
throw new InvalidProgramException("How could a variable be a function designator?");
// %eax = function_name
// state.MOVL(name, Reg.EAX);
// return Reg.EAX;
case ExprTypeKind.CHAR:
// %eax = [char -> long](off(%ebp))
state.MOVSBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
// %eax = [uchar -> ulong](off(%ebp))
state.MOVZBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
// %eax = [short -> long](off(%ebp))
state.MOVSWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
// %eax = [ushort -> ulong](off(%ebp))
state.MOVZWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.ARRAY:
// %eax = (off(%ebp))
state.LEA(offset, Reg.EBP, Reg.EAX); // source address
return Reg.EAX;
default:
throw new InvalidOperationException($"Cannot get value of {this.Type.Kind}");
}
case Env.EntryKind.GLOBAL:
switch (this.Type.Kind) {
case ExprTypeKind.CHAR:
state.MOVSBL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
state.MOVZBL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
state.MOVSWL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
state.MOVZWL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
state.MOVL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FUNCTION:
state.MOVL("$" + this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
state.FLDS(this.Name);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
state.FLDL(this.Name);
return Reg.ST0;
case ExprTypeKind.STRUCT_OR_UNION:
state.MOVL($"${this.Name}", Reg.EAX);
return Reg.EAX;
//state.LEA(name, Reg.ESI); // source address
//state.CGenExpandStackBy(Utils.RoundUp(Type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI); // destination address
//state.MOVL(Type.SizeOf, Reg.ECX); // nbytes
//state.CGenMemCpy();
//return Reg.STACK;
case ExprTypeKind.VOID:
throw new InvalidProgramException("How could a variable be void?");
//state.MOVL(0, Reg.EAX);
//return Reg.EAX;
case ExprTypeKind.ARRAY:
state.MOVL($"${this.Name}", Reg.EAX);
return Reg.EAX;
default:
throw new InvalidProgramException("cannot get the Value of a " + this.Type.Kind);
}
case Env.EntryKind.TYPEDEF:
default:
throw new InvalidProgramException("cannot get the Value of a " + entry.Kind);
}
}
public override Reg CGenValue(CGenState state) {
// 1. %eax = &left
this.Left.CGenAddress(state);
// 2. push %eax
Int32 pos = state.CGenPushLong(Reg.EAX);
Reg ret = this.Right.CGenValue(state);
switch (this.Left.Type.Kind) {
case ExprTypeKind.CHAR:
case ExprTypeKind.UCHAR:
// pop %ebx
// now %ebx = %Left
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVB(Reg.AL, 0, Reg.EBX);
return Reg.EAX;
case ExprTypeKind.SHORT:
case ExprTypeKind.USHORT:
// pop %ebx
// now %ebx = %Left
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVW(Reg.AX, 0, Reg.EBX);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
// pop %ebx
// now %ebx = &Left
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %al
state.MOVL(Reg.EAX, 0, Reg.EBX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
// pop %ebx
// now %ebx = &Left
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %st(0)
state.FSTS(0, Reg.EBX);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
// pop %ebx
// now %ebx = &Left
state.CGenPopLong(pos, Reg.EBX);
// *%ebx = %st(0)
state.FSTL(0, Reg.EBX);
return Reg.ST0;
case ExprTypeKind.STRUCT_OR_UNION:
// pop %edi
// now %edi = &Left
state.CGenPopLong(pos, Reg.EDI);
// %esi = &Right
state.MOVL(Reg.EAX, Reg.ESI);
// %ecx = nbytes
state.MOVL(this.Left.Type.SizeOf, Reg.ECX);
state.CGenMemCpy();
// %eax = &Left
state.MOVL(Reg.EDI, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FUNCTION:
case ExprTypeKind.VOID:
case ExprTypeKind.ARRAY:
case ExprTypeKind.INCOMPLETE_ARRAY:
default:
throw new InvalidProgramException("cannot assign to a " + this.Type.Kind);
}
}
public override Reg CGenValue(CGenState state) {
Int32 label_set = state.label_idx;
state.label_idx++;
Int32 label_finish = state.label_idx;
state.label_idx++;
Reg ret = this.Left.CGenValue(state);
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
state.JNZ(label_set);
break;
case Reg.ST0:
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
state.JNZ(label_set);
break;
default:
throw new InvalidProgramException();
}
ret = this.Right.CGenValue(state);
switch (ret) {
case Reg.EAX:
state.TESTL(Reg.EAX, Reg.EAX);
state.JNZ(label_set);
break;
case Reg.ST0:
state.FLDZ();
state.FUCOMIP();
state.FSTP(Reg.ST0);
state.JNZ(label_set);
break;
default:
throw new InvalidProgramException();
}
state.MOVL(0, Reg.EAX);
state.JMP(label_finish);
state.CGenLabel(label_set);
state.MOVL(1, Reg.EAX);
state.CGenLabel(label_finish);
return Reg.EAX;
}
public override void OperateULong(CGenState state) {
state.CLTD();
state.DIVL(Reg.EBX);
state.MOVL(Reg.EDX, Reg.EAX);
}
public override void CGenStmt(Env env, CGenState state) {
ExprType ret_type = env.GetCurrentFunction().ReturnType;
Int32 stack_size = state.StackSize;
if (this.ExprOpt.IsSome) {
// Evaluate the Value.
this.ExprOpt.Value.CGenValue(state);
// If the function returns a struct, copy it to the address given by 8(%ebp).
if (this.ExprOpt.Value.Type is StructOrUnionType) {
state.MOVL(Reg.EAX, Reg.ESI);
state.MOVL(2 * ExprType.SIZEOF_POINTER, Reg.EBP, Reg.EDI);
state.MOVL(this.ExprOpt.Value.Type.SizeOf, Reg.ECX);
state.CGenMemCpy();
state.MOVL(2 * ExprType.SIZEOF_POINTER, Reg.EBP, Reg.EAX);
}
// Restore stack size.
state.CGenForceStackSizeTo(stack_size);
}
// Jump to end of the function.
state.JMP(state.ReturnLabel);
}
