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#include "stdafx.h"
#include "Return.h"
#include "Function.h"
#include "Cast.h"
#include "Compiler/Exception.h"
namespace storm {
namespace bs {
Return::Return(SrcPos pos, Block *block) : Expr(pos), retInfo(findReturn(pos, block)) {
retInfo->checkResult(pos, block->scope, null);
}
Return::Return(SrcPos pos, Block *block, Expr *expr) : Expr(pos), retInfo(findReturn(pos, block)) {
this->expr = retInfo->checkResult(pos, block->scope, expr);
}
ExprResult Return::result() {
return noReturn();
}
void Return::code(CodeGen *state, CodeResult *r) {
if (retInfo->type == Value())
voidCode(state);
else
valueCode(state);
}
void Return::voidCode(CodeGen *state) {
using namespace code;
if (retInfo->inlineResult) {
*state->l << jmpBlock(retInfo->inlineLabel, retInfo->inlineBlock);
} else {
*state->l << fnRet();
}
}
void Return::valueCode(CodeGen *state) {
using namespace code;
if (retInfo->inlineResult) {
// Note: We need 'split', otherwise we will activate the same variable multiple times.
// It is the caller's responsibility to activate the result if required.
expr->code(state, retInfo->inlineResult->split(state));
*state->l << jmpBlock(retInfo->inlineLabel, retInfo->inlineBlock);
} else {
// If we can get the result as a reference, do that as we avoid a copy. The exception
// is built-in types, as we can copy them cheaply.
Value type = retInfo->type;
if (!type.isPrimitive() && expr->result().type().ref)
type = retInfo->type.asRef();
CodeResult *r = new (this) CodeResult(type, state->block);
expr->code(state, r);
if (type.ref)
*state->l << fnRetRef(r->location(state));
else
state->returnValue(r->location(state));
}
}
ReturnInfo *Return::findReturn(SrcPos pos, Block *block) {
BlockLookup *lookup = block->lookup;
while (lookup) {
Block *block = lookup->block;
if (ReturnPoint *root = as<ReturnPoint>(block))
return root->info;
if (FnBody *body = as<FnBody>(block))
return body->info;
lookup = as<BlockLookup>(lookup->parent());
}
throw new (this) SyntaxError(pos, S("A return statement is not located inside a function."));
}
void Return::toS(StrBuf *to) const {
*to << S("return");
if (expr)
*to << S(" ") << expr;
}
ReturnInfo::ReturnInfo(Value type) : type(type) {}
MAYBE(Expr *) ReturnInfo::checkResult(SrcPos pos, Scope scope, Expr *expr) {
if (!expr) {
if (this->type != Value())
throw new (this) SyntaxError(pos, TO_S(this, S("Trying to return void from a function that returns ") << type));
} else {
if (this->type == Value())
throw new (this) SyntaxError(pos, S("Trying to return a value from a function that returns void."));
expr = expectCastTo(expr, type, scope);
}
return expr;
}
ReturnPoint::ReturnPoint(SrcPos pos, Scope scope, Value type) : Block(pos, scope) {
info = new (this) ReturnInfo(type);
}
ReturnPoint::ReturnPoint(SrcPos pos, Block *parent, Value type) : Block(pos, parent) {
info = new (this) ReturnInfo(type);
}
ReturnPoint::ReturnPoint(SrcPos pos, Scope scope, ReturnInfo *info) : Block(pos, scope), info(info) {}
ReturnPoint::ReturnPoint(SrcPos pos, Block *parent, ReturnInfo *info) : Block(pos, parent), info(info) {}
ExprResult ReturnPoint::result() {
return info->type;
}
void ReturnPoint::body(Expr *e) {
bodyExpr = expectCastTo(e, info->type, scope);
}
void ReturnPoint::blockCode(CodeGen *state, CodeResult *to, code::Block newBlock) {
info->inlineResult = to;
info->inlineLabel = state->l->label();
info->inlineBlock = newBlock;
*state->l << begin(newBlock);
CodeGen *subState = state->child(newBlock);
if (bodyExpr) {
// Note: Avoid duplicate activation by asking this block to not activate the variable.
bodyExpr->code(subState, to->split(state));
}
*state->l << end(newBlock);
*state->l << info->inlineLabel;
// We need to ensure that the result was created.
to->created(state);
}
void ReturnPoint::toS(StrBuf *to) const {
*to << S("<capture return of: ") << info->type << S("> {\n");
to->indent();
if (bodyExpr) {
*to << bodyExpr;
}
to->dedent();
*to << S("\n}");
}
}
}
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