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public CGenForceStackSizeTo ( |
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| nbytes | ||
| return | void | |
public override void CGenStmt(Env env, CGenState state) {
if (this.ExprOpt.IsSome) {
Int32 stack_size = state.StackSize;
this.ExprOpt.Value.CGenValue(state);
state.CGenForceStackSizeTo(stack_size);
}
}
// * 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($"How could a {expr.Type.Kind} be in a init list?");
default:
throw new InvalidProgramException();
}
state.CGenForceStackSizeTo(stack_size);
});
} // stack object
}
public override Reg CGenValue(CGenState state) {
// GCC's IA-32 calling convention
// Caller is responsible to push all arguments to the stack in reverse order.
// Each argument is at least aligned to 4 bytes - even a char would take 4 bytes.
// The return Value is stored in %eax, or %st(0), if it is a scalar.
//
// The stack would look like this after pushing all the arguments:
// +--------+
// | .... |
// +--------+
// | argn |
// +--------+
// | .... |
// +--------+
// | arg2 |
// +--------+
// | arg1 |
// +--------+ <- %esp before call
//
// Things are different with structs and unions.
// Since structs may not fit in 4 bytes, it has to be returned in memory.
// Caller allocates a chunk of memory for the struct and push the address of it as an extra argument.
// Callee returns %eax with that address.
//
// The stack would look like this after pushing all the arguments:
// +--------+
// +--> | struct | <- struct should be returned here.
// | +--------+
// | | argn |
// | +--------+
// | | .... |
// | +--------+
// | | arg2 |
// | +--------+
// | | arg1 |
// | +--------+
// +----| addr | <- %esp before call
// +--------+
//
state.NEWLINE();
state.COMMENT($"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;
}
//
// test Cond
// jz false ---+
// true_expr |
// +------- jmp finish |
// | false: <--------+
// | false_expr
// +--> finish:
//
public override Reg CGenValue(CGenState state) {
Int32 stack_size = state.StackSize;
Reg ret = this.Cond.CGenValue(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 = "BinaryComparisonOp.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);
this.TrueExpr.CGenValue(state);
state.JMP(finish_label);
state.CGenLabel(false_label);
ret = this.FalseExpr.CGenValue(state);
state.CGenLabel(finish_label);
return ret;
}
public Reg CGenExprStmt(Env env, Expr expr, CGenState state) {
Int32 stack_size = state.StackSize;
Reg ret = expr.CGenValue(state);
state.CGenForceStackSizeTo(stack_size);
return ret;
}
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);
}
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) {
// Inside a switch statement, the initializations are ignored,
// but the stack size should be changed.
List<Tuple<Env, Decln>> declns;
List<Tuple<Env, Stmt>> stmts;
var compoundStmt = this.Stmt as CompoundStmt;
if (compoundStmt == null) {
throw new NotImplementedException();
}
declns = compoundStmt.Declns;
stmts = compoundStmt.Stmts;
// Track all case values.
IReadOnlyList<Int32> values = CaseLabelsGrabber.GrabLabels(this);
// Make sure there are no duplicates.
if (values.Distinct().Count() != values.Count) {
throw new InvalidOperationException("case labels not unique.");
}
// Request labels for these values.
Dictionary<Int32, Int32> value_to_label = values.ToDictionary(value => value, value => state.RequestLabel());
Int32 label_finish = state.RequestLabel();
Int32 num_default_stmts = stmts.Count(_ => _.Item2 is DefaultStmt);
if (num_default_stmts > 1) {
throw new InvalidOperationException("duplicate defaults.");
}
Int32 label_default =
num_default_stmts == 1 ?
state.RequestLabel() :
label_finish;
Int32 saved_stack_size = state.StackSize;
Int32 stack_size =
declns.Any() ?
declns.Last().Item1.StackSize :
saved_stack_size;
// 1. Evaluate Expr.
CGenExprStmt(env, this.Expr, state);
// 2. Expand stack.
state.CGenForceStackSizeTo(stack_size);
// 3. Make the Jump list.
foreach (KeyValuePair<Int32, Int32> value_label_pair in value_to_label) {
state.CMPL(value_label_pair.Key, Reg.EAX);
state.JZ(value_label_pair.Value);
}
state.JMP(label_default);
// 4. List all the statements.
state.InSwitch(label_finish, label_default, value_to_label);
foreach (Tuple<Env, Stmt> env_stmt_pair in stmts) {
env_stmt_pair.Item2.CGenStmt(env_stmt_pair.Item1, state);
}
state.OutLabels();
// 5. finish:
state.CGenLabel(label_finish);
// 6. Restore stack size.
state.CGenForceStackSizeTo(saved_stack_size);
}
