unsigned Test (unsigned Label, int Invert)
/* Evaluate a boolean test expression and jump depending on the result of
** the test and on Invert. The function returns one of the TESTEXPR_xx codes
** defined above. If the jump is always true, a warning is output.
*/
{
ExprDesc Expr;
unsigned Result;
/* Read a boolean expression */
BoolExpr (hie0, &Expr);
/* Check for a constant expression */
if (ED_IsConstAbs (&Expr)) {
/* Result is constant, so we know the outcome */
Result = (Expr.IVal != 0);
/* Constant rvalue */
if (!Invert && Expr.IVal == 0) {
g_jump (Label);
Warning ("Unreachable code");
} else if (Invert && Expr.IVal != 0) {
g_jump (Label);
}
} else {
/* Result is unknown */
Result = TESTEXPR_UNKNOWN;
/* If the expr hasn't set condition codes, set the force-test flag */
if (!ED_IsTested (&Expr)) {
ED_MarkForTest (&Expr);
}
/* Load the value into the primary register */
LoadExpr (CF_FORCECHAR, &Expr);
/* Generate the jump */
if (Invert) {
g_truejump (CF_NONE, Label);
} else {
g_falsejump (CF_NONE, Label);
}
}
/* Return the result */
return Result;
}
static void ContinueStatement (void)
/* Handle the 'continue' statement */
{
LoopDesc* L;
/* Skip the continue */
NextToken ();
/* Get the current loop descriptor */
L = CurrentLoop ();
if (L) {
/* Search for a loop that has a continue label. */
do {
if (L->ContinueLabel) {
break;
}
L = L->Next;
} while (L);
}
/* Did we find it? */
if (L == 0) {
Error ("`continue' statement not within a loop");
return;
}
/* Correct the stackpointer if needed */
g_space (StackPtr - L->StackPtr);
/* Jump to next loop iteration */
g_jump (L->ContinueLabel);
}
static void WhileStatement (void)
/* Handle the 'while' statement */
{
int PendingToken;
CodeMark CondCodeStart; /* Start of condition evaluation code */
CodeMark CondCodeEnd; /* End of condition evaluation code */
CodeMark Here; /* "Here" location of code */
/* Get the loop control labels */
unsigned LoopLabel = GetLocalLabel ();
unsigned BreakLabel = GetLocalLabel ();
unsigned CondLabel = GetLocalLabel ();
/* Skip the while token */
NextToken ();
/* Add the loop to the loop stack. In case of a while loop, the condition
** label is used for continue statements.
*/
AddLoop (BreakLabel, CondLabel);
/* We will move the code that evaluates the while condition to the end of
** the loop, so generate a jump here.
*/
g_jump (CondLabel);
/* Remember the current position */
GetCodePos (&CondCodeStart);
/* Emit the code position label */
g_defcodelabel (CondLabel);
/* Test the loop condition */
TestInParens (LoopLabel, 1);
/* Remember the end of the condition evaluation code */
GetCodePos (&CondCodeEnd);
/* Define the head label */
g_defcodelabel (LoopLabel);
/* Loop body */
Statement (&PendingToken);
/* Move the test code here */
GetCodePos (&Here);
MoveCode (&CondCodeStart, &CondCodeEnd, &Here);
/* Exit label */
g_defcodelabel (BreakLabel);
/* Eat remaining tokens that were delayed because of line info
** correctness
*/
SkipPending (PendingToken);
/* Remove the loop from the loop stack */
DelLoop ();
}
static int IfStatement (void)
/* Handle an 'if' statement */
{
unsigned Label1;
unsigned TestResult;
int GotBreak;
/* Skip the if */
NextToken ();
/* Generate a jump label and parse the condition */
Label1 = GetLocalLabel ();
TestResult = TestInParens (Label1, 0);
/* Parse the if body */
GotBreak = Statement (0);
/* Else clause present? */
if (CurTok.Tok != TOK_ELSE) {
g_defcodelabel (Label1);
/* Since there's no else clause, we're not sure, if the a break
** statement is really executed.
*/
return 0;
} else {
/* Generate a jump around the else branch */
unsigned Label2 = GetLocalLabel ();
g_jump (Label2);
/* Skip the else */
NextToken ();
/* If the if expression was always true, the code in the else branch
** is never executed. Output a warning if this is the case.
*/
if (TestResult == TESTEXPR_TRUE) {
Warning ("Unreachable code");
}
/* Define the target for the first test */
g_defcodelabel (Label1);
/* Total break only if both branches had a break. */
GotBreak &= Statement (0);
/* Generate the label for the else clause */
g_defcodelabel (Label2);
/* Done */
return GotBreak;
}
}
static void WhileStatement (void)
/* Handle the 'while' statement */
{
int PendingToken;
/* Get the loop control labels */
unsigned LoopLabel = GetLocalLabel ();
unsigned BreakLabel = GetLocalLabel ();
/* Skip the while token */
NextToken ();
/* Add the loop to the loop stack. In case of a while loop, the loop head
* label is used for continue statements.
*/
AddLoop (BreakLabel, LoopLabel);
/* Define the head label */
g_defcodelabel (LoopLabel);
/* Test the loop condition */
TestInParens (BreakLabel, 0);
/* Loop body */
Statement (&PendingToken);
/* Jump back to loop top */
g_jump (LoopLabel);
/* Exit label */
g_defcodelabel (BreakLabel);
/* Eat remaining tokens that were delayed because of line info
* correctness
*/
SkipPending (PendingToken);
/* Remove the loop from the loop stack */
DelLoop ();
}
static void ReturnStatement (void)
/* Handle the 'return' statement */
{
ExprDesc Expr;
NextToken ();
if (CurTok.Tok != TOK_SEMI) {
/* Evaluate the return expression */
hie0 (&Expr);
/* If we return something in a void function, print an error and
** ignore the value. Otherwise convert the value to the type of the
** return.
*/
if (F_HasVoidReturn (CurrentFunc)) {
Error ("Returning a value in function with return type void");
} else {
/* Convert the return value to the type of the function result */
TypeConversion (&Expr, F_GetReturnType (CurrentFunc));
/* Load the value into the primary */
LoadExpr (CF_NONE, &Expr);
}
} else if (!F_HasVoidReturn (CurrentFunc) && !F_HasOldStyleIntRet (CurrentFunc)) {
Error ("Function `%s' must return a value", F_GetFuncName (CurrentFunc));
}
/* Mark the function as having a return statement */
F_ReturnFound (CurrentFunc);
/* Cleanup the stack in case we're inside a block with locals */
g_space (StackPtr - F_GetTopLevelSP (CurrentFunc));
/* Output a jump to the function exit code */
g_jump (F_GetRetLab (CurrentFunc));
}
static void BreakStatement (void)
/* Handle the 'break' statement */
{
LoopDesc* L;
/* Skip the break */
NextToken ();
/* Get the current loop descriptor */
L = CurrentLoop ();
/* Check if we are inside a loop */
if (L == 0) {
/* Error: No current loop */
Error ("`break' statement not within loop or switch");
return;
}
/* Correct the stack pointer if needed */
g_space (StackPtr - L->StackPtr);
/* Jump to the exit label of the loop */
g_jump (L->BreakLabel);
}
void SwitchStatement (void)
/* Handle a switch statement for chars with a cmp cascade for the selector */
{
ExprDesc SwitchExpr; /* Switch statement expression */
CodeMark CaseCodeStart; /* Start of code marker */
CodeMark SwitchCodeStart;/* Start of switch code */
CodeMark SwitchCodeEnd; /* End of switch code */
unsigned ExitLabel; /* Exit label */
unsigned SwitchCodeLabel;/* Label for the switch code */
int HaveBreak = 0; /* True if the last statement had a break */
int RCurlyBrace; /* True if last token is right curly brace */
SwitchCtrl* OldSwitch; /* Pointer to old switch control data */
SwitchCtrl SwitchData; /* New switch data */
/* Eat the "switch" token */
NextToken ();
/* Read the switch expression and load it into the primary. It must have
* integer type.
*/
ConsumeLParen ();
Expression0 (&SwitchExpr);
if (!IsClassInt (SwitchExpr.Type)) {
Error ("Switch quantity is not an integer");
/* To avoid any compiler errors, make the expression a valid int */
ED_MakeConstAbsInt (&SwitchExpr, 1);
}
ConsumeRParen ();
/* Add a jump to the switch code. This jump is usually unnecessary,
* because the switch code will moved up just behind the switch
* expression. However, in rare cases, there's a label at the end of
* the switch expression. This label will not get moved, so the code
* jumps around the switch code, and after moving the switch code,
* things look really weird. If we add a jump here, we will never have
* a label attached to the current code position, and the jump itself
* will get removed by the optimizer if it is unnecessary.
*/
SwitchCodeLabel = GetLocalLabel ();
g_jump (SwitchCodeLabel);
/* Remember the current code position. We will move the switch code
* to this position later.
*/
GetCodePos (&CaseCodeStart);
/* Setup the control structure, save the old and activate the new one */
SwitchData.Nodes = NewCollection ();
SwitchData.ExprType = UnqualifiedType (SwitchExpr.Type[0].C);
SwitchData.Depth = SizeOf (SwitchExpr.Type);
SwitchData.DefaultLabel = 0;
OldSwitch = Switch;
Switch = &SwitchData;
/* Get the exit label for the switch statement */
ExitLabel = GetLocalLabel ();
/* Create a loop so we may use break. */
AddLoop (ExitLabel, 0);
/* Make sure a curly brace follows */
if (CurTok.Tok != TOK_LCURLY) {
Error ("`{' expected");
}
/* Parse the following statement, which will actually be a compound
* statement because of the curly brace at the current input position
*/
HaveBreak = Statement (&RCurlyBrace);
/* Check if we had any labels */
if (CollCount (SwitchData.Nodes) == 0 && SwitchData.DefaultLabel == 0) {
Warning ("No case labels");
}
/* If the last statement did not have a break, we may have an open
* label (maybe from an if or similar). Emitting code and then moving
* this code to the top will also move the label to the top which is
* wrong. So if the last statement did not have a break (which would
* carry the label), add a jump to the exit. If it is useless, the
* optimizer will remove it later.
*/
if (!HaveBreak) {
g_jump (ExitLabel);
}
/* Remember the current position */
GetCodePos (&SwitchCodeStart);
/* Output the switch code label */
g_defcodelabel (SwitchCodeLabel);
/* Generate code */
if (SwitchData.DefaultLabel == 0) {
/* No default label, use switch exit */
SwitchData.DefaultLabel = ExitLabel;
}
g_switch (SwitchData.Nodes, SwitchData.DefaultLabel, SwitchData.Depth);
/* Move the code to the front */
GetCodePos (&SwitchCodeEnd);
MoveCode (&SwitchCodeStart, &SwitchCodeEnd, &CaseCodeStart);
/* Define the exit label */
g_defcodelabel (ExitLabel);
/* Exit the loop */
DelLoop ();
/* Switch back to the enclosing switch statement if any */
Switch = OldSwitch;
/* Free the case value tree */
FreeCaseNodeColl (SwitchData.Nodes);
/* If the case statement was (correctly) terminated by a closing curly
* brace, skip it now.
*/
if (RCurlyBrace) {
NextToken ();
}
}
static void ForStatement (void)
/* Handle a 'for' statement */
{
ExprDesc lval1;
ExprDesc lval3;
int HaveIncExpr;
CodeMark IncExprStart;
CodeMark IncExprEnd;
int PendingToken;
/* Get several local labels needed later */
unsigned TestLabel = GetLocalLabel ();
unsigned BreakLabel = GetLocalLabel ();
unsigned IncLabel = GetLocalLabel ();
unsigned BodyLabel = GetLocalLabel ();
/* Skip the FOR token */
NextToken ();
/* Add the loop to the loop stack. A continue jumps to the start of the
** the increment condition.
*/
AddLoop (BreakLabel, IncLabel);
/* Skip the opening paren */
ConsumeLParen ();
/* Parse the initializer expression */
if (CurTok.Tok != TOK_SEMI) {
Expression0 (&lval1);
}
ConsumeSemi ();
/* Label for the test expressions */
g_defcodelabel (TestLabel);
/* Parse the test expression */
if (CurTok.Tok != TOK_SEMI) {
Test (BodyLabel, 1);
g_jump (BreakLabel);
} else {
g_jump (BodyLabel);
}
ConsumeSemi ();
/* Remember the start of the increment expression */
GetCodePos (&IncExprStart);
/* Label for the increment expression */
g_defcodelabel (IncLabel);
/* Parse the increment expression */
HaveIncExpr = (CurTok.Tok != TOK_RPAREN);
if (HaveIncExpr) {
Expression0 (&lval3);
}
/* Jump to the test */
g_jump (TestLabel);
/* Remember the end of the increment expression */
GetCodePos (&IncExprEnd);
/* Skip the closing paren */
ConsumeRParen ();
/* Loop body */
g_defcodelabel (BodyLabel);
Statement (&PendingToken);
/* If we had an increment expression, move the code to the bottom of
** the loop. In this case we don't need to jump there at the end of
** the loop body.
*/
if (HaveIncExpr) {
CodeMark Here;
GetCodePos (&Here);
MoveCode (&IncExprStart, &IncExprEnd, &Here);
} else {
/* Jump back to the increment expression */
g_jump (IncLabel);
}
/* Skip a pending token if we have one */
SkipPending (PendingToken);
/* Declare the break label */
g_defcodelabel (BreakLabel);
/* Remove the loop from the loop stack */
DelLoop ();
}
