/**
* 翻译break 语句
* A break statement terminates the execution of associated
* switch or loop.
*
* break is translated into:
* goto switch or loop's nextBB
* nextBB:
* ...
*/
static void TranslateBreakStatement (AstStatement stmt)
{
AstBreakStatement brkStmt = AsBreak(stmt);
if (brkStmt->target->kind == NK_SwitchStatement) {
/* switch 在跳转 */
GenerateJump (AsSwitch(brkStmt->target)->nextBB);
} else {
/* loop 跳转 */
GenerateJump (AsLoop(brkStmt->target)->nextBB);
}
StartBBlock (CreateBBlock ());
}
/**
* 翻译do 语句
*
* do stmt while (expr) is translated into:
* loopBB:
* stmt
* contBB:
* if (expr) goto loopBB
* nextBB:
* ...
*/
static void TranslateDoStatement (AstStatement stmt)
{
AstLoopStatement doStmt = AsLoop(stmt);
doStmt->loopBB = CreateBBlock ();
doStmt->contBB = CreateBBlock ();
doStmt->nextBB = CreateBBlock ();
/* do 语句先执行循环体 */
StartBBlock (doStmt->loopBB);
TranslateStatement (doStmt->stmt);
/* 判断条件,分支 */
StartBBlock (doStmt->contBB);
TranslateBranch (doStmt->expr, doStmt->loopBB, doStmt->nextBB);
StartBBlock (doStmt->nextBB);
}
/**
* 翻译while 语句
*
* while (expr) stmt is translated into:
* goto contBB
* loopBB:
* stmt
* contBB:
* if (expr) goto loopBB
* nextBB:
* ...
*/
static void TranslateWhileStatement (AstStatement stmt)
{
AstLoopStatement whileStmt = AsLoop(stmt);
/* 循环体基本块 */
whileStmt->loopBB = CreateBBlock ();
/* 继续判断条件 */
whileStmt->contBB = CreateBBlock ();
/* 循环结束后基本块 */
whileStmt->nextBB = CreateBBlock ();
/* 条件 */
GenerateJump (whileStmt->contBB);
/* 循环体 */
StartBBlock (whileStmt->loopBB);
TranslateStatement (whileStmt->stmt);
/* 判断条件,分支 */
StartBBlock (whileStmt->contBB);
TranslateBranch (whileStmt->expr, whileStmt->loopBB, whileStmt->nextBB);
StartBBlock (whileStmt->nextBB);
}
static void DumpStatement(AstStatement stmt, int pos)
{
switch (stmt->kind)
{
case NK_ExpressionStatement:
DumpExpression(AsExpr(stmt)->expr, pos);
break;
case NK_LabelStatement:
fprintf(ASTFile, "(label %s:\n", AsLabel(stmt)->id);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsLabel(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-label)");
break;
case NK_CaseStatement:
fprintf(ASTFile, "(case ");
DumpExpression(AsCase(stmt)->expr, pos + 7);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsCase(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-case)");
break;
case NK_DefaultStatement:
fprintf(ASTFile, "(default ");
DumpStatement(AsDef(stmt)->stmt, pos + 10);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-default)");
break;
case NK_IfStatement:
fprintf(ASTFile, "(if ");
DumpExpression(AsIf(stmt)->expr, pos + 5);
LeftAlign(ASTFile, pos + 2);
fprintf(ASTFile, "(then ");
LeftAlign(ASTFile, pos + 4);
DumpStatement(AsIf(stmt)->thenStmt, pos + 4);
LeftAlign(ASTFile, pos + 2);
fprintf(ASTFile, "end-then)");
if (AsIf(stmt)->elseStmt != NULL)
{
LeftAlign(ASTFile, pos + 2);
fprintf(ASTFile, "(else ");
LeftAlign(ASTFile, pos + 4);
DumpStatement(AsIf(stmt)->elseStmt, pos + 4);
LeftAlign(ASTFile, pos + 2);
fprintf(ASTFile, "end-else)");
}
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-if)");
break;
case NK_SwitchStatement:
fprintf(ASTFile, "(switch ");
DumpExpression(AsSwitch(stmt)->expr, pos + 9);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsSwitch(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-switch)");
break;
case NK_WhileStatement:
fprintf(ASTFile, "(while ");
DumpExpression(AsLoop(stmt)->expr, pos + 8);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsLoop(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-while)");
break;
case NK_DoStatement:
fprintf(ASTFile, "(do ");
DumpExpression(AsLoop(stmt)->expr, pos + 5);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsLoop(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, ")");
break;
case NK_ForStatement:
fprintf(ASTFile, "(for ");
DumpExpression(AsFor(stmt)->initExpr, pos + 6);
LeftAlign(ASTFile, pos + 6);
DumpExpression(AsFor(stmt)->expr, pos + 6);
LeftAlign(ASTFile, pos + 6);
DumpExpression(AsFor(stmt)->incrExpr, pos + 6);
LeftAlign(ASTFile, pos + 2);
DumpStatement(AsFor(stmt)->stmt, pos + 2);
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "end-for)");
break;
case NK_GotoStatement:
fprintf(ASTFile, "(goto %s)", AsGoto(stmt)->id);
break;
case NK_ContinueStatement:
fprintf(ASTFile, "(continue)");
break;
case NK_BreakStatement:
fprintf(ASTFile, "(break)");
break;
case NK_ReturnStatement:
fprintf(ASTFile, "(ret ");
DumpExpression(AsRet(stmt)->expr, pos + 5);
fprintf(ASTFile, ")");
break;
case NK_CompoundStatement:
{
AstNode p = ((AstCompoundStatement)stmt)->stmts;
fprintf(ASTFile, "{");
while (p != NULL)
{
LeftAlign(ASTFile, pos + 2);
DumpStatement((AstStatement)p, pos + 2);
if (p->next != NULL)
fprintf(ASTFile, "\n");
p = p->next;
}
LeftAlign(ASTFile, pos);
fprintf(ASTFile, "}");
break;
}
default:
assert(0);
}
}
