/*************************************
* Closures are implemented by taking the local variables that
* need to survive the scope of the function, and copying them
* into a gc allocated chuck of memory. That chunk, called the
* closure here, is inserted into the linked list of stack
* frames instead of the usual stack frame.
*
* buildClosure() inserts code just after the function prolog
* is complete. It allocates memory for the closure, allocates
* a local variable (sclosure) to point to it, inserts into it
* the link to the enclosing frame, and copies into it the parameters
* that are referred to in nested functions.
* In VarExp::toElem and SymOffExp::toElem, when referring to a
* variable that is in a closure, takes the offset from sclosure rather
* than from the frame pointer.
*
* getEthis() and NewExp::toElem need to use sclosure, if set, rather
* than the current frame pointer.
*/
void buildClosure(FuncDeclaration *fd, IRState *irs)
{
if (fd->needsClosure())
{
// Generate closure on the heap
// BUG: doesn't capture variadic arguments passed to this function
/* BUG: doesn't handle destructors for the local variables.
* The way to do it is to make the closure variables the fields
* of a class object:
* class Closure {
* vtbl[]
* monitor
* ptr to destructor
* sthis
* ... closure variables ...
* ~this() { call destructor }
* }
*/
//printf("FuncDeclaration::buildClosure() %s\n", toChars());
/* Generate type name for closure struct */
const char *name1 = "CLOSURE.";
const char *name2 = fd->toPrettyChars();
size_t namesize = strlen(name1)+strlen(name2)+1;
char *closname = (char *) calloc(namesize, sizeof(char));
strcat(strcat(closname, name1), name2);
/* Build type for closure */
type *Closstru = type_struct_class(closname, Target::ptrsize, 0, NULL, NULL, false, false, true);
symbol_struct_addField(Closstru->Ttag, "__chain", Type_toCtype(Type::tvoidptr), 0);
Symbol *sclosure;
sclosure = symbol_name("__closptr", SCauto, type_pointer(Closstru));
sclosure->Sflags |= SFLtrue | SFLfree;
symbol_add(sclosure);
irs->sclosure = sclosure;
unsigned offset = Target::ptrsize; // leave room for previous sthis
for (size_t i = 0; i < fd->closureVars.dim; i++)
{
VarDeclaration *v = fd->closureVars[i];
//printf("closure var %s\n", v->toChars());
assert(v->isVarDeclaration());
if (v->needsAutoDtor())
{
/* Because the value needs to survive the end of the scope!
*/
v->error("has scoped destruction, cannot build closure");
}
if (v->isargptr)
{
/* See Bugzilla 2479
* This is actually a bug, but better to produce a nice
* message at compile time rather than memory corruption at runtime
*/
v->error("cannot reference variadic arguments from closure");
}
/* Align and allocate space for v in the closure
* just like AggregateDeclaration::addField() does.
*/
unsigned memsize;
unsigned memalignsize;
structalign_t xalign;
if (v->storage_class & STClazy)
{
/* Lazy variables are really delegates,
* so give same answers that TypeDelegate would
*/
memsize = Target::ptrsize * 2;
memalignsize = memsize;
xalign = STRUCTALIGN_DEFAULT;
}
else if (ISWIN64REF(v))
{
memsize = v->type->size();
memalignsize = v->type->alignsize();
xalign = v->alignment;
}
else if (ISREF(v, NULL))
{
// reference parameters are just pointers
memsize = Target::ptrsize;
memalignsize = memsize;
xalign = STRUCTALIGN_DEFAULT;
}
else
{
memsize = v->type->size();
memalignsize = v->type->alignsize();
xalign = v->alignment;
}
AggregateDeclaration::alignmember(xalign, memalignsize, &offset);
v->offset = offset;
offset += memsize;
/* Set Sscope to closure */
Symbol *vsym = toSymbol(v);
assert(vsym->Sscope == NULL);
vsym->Sscope = sclosure;
/* Add variable as closure type member */
symbol_struct_addField(Closstru->Ttag, vsym->Sident, vsym->Stype, v->offset);
//printf("closure field %s: memalignsize: %i, offset: %i\n", vsym->Sident, memalignsize, v->offset);
/* Can't do nrvo if the variable is put in a closure, since
* what the shidden points to may no longer exist.
*/
if (fd->nrvo_can && fd->nrvo_var == v)
{
fd->nrvo_can = 0;
}
}
// offset is now the size of the closure
Closstru->Ttag->Sstruct->Sstructsize = offset;
// Allocate memory for the closure
elem *e = el_long(TYsize_t, offset);
e = el_bin(OPcall, TYnptr, el_var(getRtlsym(RTLSYM_ALLOCMEMORY)), e);
toTraceGC(irs, e, &fd->loc);
// Assign block of memory to sclosure
// sclosure = allocmemory(sz);
e = el_bin(OPeq, TYvoid, el_var(sclosure), e);
// Set the first element to sthis
// *(sclosure + 0) = sthis;
elem *ethis;
if (irs->sthis)
ethis = el_var(irs->sthis);
else
ethis = el_long(TYnptr, 0);
elem *ex = el_una(OPind, TYnptr, el_var(sclosure));
ex = el_bin(OPeq, TYnptr, ex, ethis);
e = el_combine(e, ex);
// Copy function parameters into closure
for (size_t i = 0; i < fd->closureVars.dim; i++)
{
VarDeclaration *v = fd->closureVars[i];
if (!v->isParameter())
continue;
tym_t tym = totym(v->type);
bool win64ref = ISWIN64REF(v);
if (win64ref)
{
if (v->storage_class & STClazy)
tym = TYdelegate;
}
else if (ISREF(v, NULL))
tym = TYnptr; // reference parameters are just pointers
else if (v->storage_class & STClazy)
tym = TYdelegate;
ex = el_bin(OPadd, TYnptr, el_var(sclosure), el_long(TYsize_t, v->offset));
ex = el_una(OPind, tym, ex);
elem *ev = el_var(toSymbol(v));
if (win64ref)
{
ev->Ety = TYnptr;
ev = el_una(OPind, tym, ev);
if (tybasic(ev->Ety) == TYstruct || tybasic(ev->Ety) == TYarray)
ev->ET = Type_toCtype(v->type);
}
if (tybasic(ex->Ety) == TYstruct || tybasic(ex->Ety) == TYarray)
{
::type *t = Type_toCtype(v->type);
ex->ET = t;
ex = el_bin(OPstreq, tym, ex, ev);
ex->ET = t;
}
else
ex = el_bin(OPeq, tym, ex, ev);
e = el_combine(e, ex);
}
block_appendexp(irs->blx->curblock, e);
}
}
void FuncDeclaration::buildClosure(IRState *irs)
{
if (needsClosure())
{ // Generate closure on the heap
// BUG: doesn't capture variadic arguments passed to this function
#if DMDV2
/* BUG: doesn't handle destructors for the local variables.
* The way to do it is to make the closure variables the fields
* of a class object:
* class Closure
* { vtbl[]
* monitor
* ptr to destructor
* sthis
* ... closure variables ...
* ~this() { call destructor }
* }
*/
#endif
//printf("FuncDeclaration::buildClosure()\n");
Symbol *sclosure;
sclosure = symbol_name("__closptr",SCauto,Type::tvoidptr->toCtype());
sclosure->Sflags |= SFLtrue | SFLfree;
symbol_add(sclosure);
irs->sclosure = sclosure;
unsigned offset = PTRSIZE; // leave room for previous sthis
for (size_t i = 0; i < closureVars.dim; i++)
{ VarDeclaration *v = closureVars[i];
assert(v->isVarDeclaration());
#if DMDV2
if (v->needsAutoDtor())
/* Because the value needs to survive the end of the scope!
*/
v->error("has scoped destruction, cannot build closure");
if (v->isargptr)
/* See Bugzilla 2479
* This is actually a bug, but better to produce a nice
* message at compile time rather than memory corruption at runtime
*/
v->error("cannot reference variadic arguments from closure");
#endif
/* Align and allocate space for v in the closure
* just like AggregateDeclaration::addField() does.
*/
unsigned memsize;
unsigned memalignsize;
structalign_t xalign;
#if DMDV2
if (v->storage_class & STClazy)
{
/* Lazy variables are really delegates,
* so give same answers that TypeDelegate would
*/
memsize = PTRSIZE * 2;
memalignsize = memsize;
xalign = global.structalign;
}
else if (v->isRef() || v->isOut())
{ // reference parameters are just pointers
memsize = PTRSIZE;
memalignsize = memsize;
xalign = global.structalign;
}
else
#endif
{
memsize = v->type->size();
memalignsize = v->type->alignsize();
xalign = v->alignment;
}
AggregateDeclaration::alignmember(xalign, memalignsize, &offset);
v->offset = offset;
offset += memsize;
/* Can't do nrvo if the variable is put in a closure, since
* what the shidden points to may no longer exist.
*/
if (nrvo_can && nrvo_var == v)
{
nrvo_can = 0;
}
}
// offset is now the size of the closure
// Allocate memory for the closure
elem *e;
e = el_long(TYsize_t, offset);
e = el_bin(OPcall, TYnptr, el_var(rtlsym[RTLSYM_ALLOCMEMORY]), e);
// Assign block of memory to sclosure
// sclosure = allocmemory(sz);
e = el_bin(OPeq, TYvoid, el_var(sclosure), e);
// Set the first element to sthis
// *(sclosure + 0) = sthis;
elem *ethis;
if (irs->sthis)
ethis = el_var(irs->sthis);
else
ethis = el_long(TYnptr, 0);
elem *ex = el_una(OPind, TYnptr, el_var(sclosure));
ex = el_bin(OPeq, TYnptr, ex, ethis);
e = el_combine(e, ex);
// Copy function parameters into closure
for (size_t i = 0; i < closureVars.dim; i++)
{ VarDeclaration *v = closureVars[i];
if (!v->isParameter())
continue;
tym_t tym = v->type->totym();
if (
#if !SARRAYVALUE
v->type->toBasetype()->ty == Tsarray ||
#endif
v->isOut() || v->isRef())
tym = TYnptr; // reference parameters are just pointers
#if DMDV2
else if (v->storage_class & STClazy)
tym = TYdelegate;
#endif
ex = el_bin(OPadd, TYnptr, el_var(sclosure), el_long(TYsize_t, v->offset));
ex = el_una(OPind, tym, ex);
if (tybasic(ex->Ety) == TYstruct || tybasic(ex->Ety) == TYarray)
{
::type *t = v->type->toCtype();
ex->ET = t;
ex = el_bin(OPstreq, tym, ex, el_var(v->toSymbol()));
ex->ET = t;
}
else
ex = el_bin(OPeq, tym, ex, el_var(v->toSymbol()));
e = el_combine(e, ex);
}
block_appendexp(irs->blx->curblock, e);
}
}