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* fixed returning small but "non-simple" records on ARM platforms that use

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the old APCS calling convention (such as iOS): they are returned by
    reference

git-svn-id: trunk@20665 -
This commit is contained in:
Jonas Maebe 2012-03-29 20:54:51 +00:00
parent 8525a30d9f
commit 2a8f624eb0
1 changed files with 67 additions and 2 deletions
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69
compiler/arm/cpupara.pas
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@ -55,7 +55,7 @@ unit cpupara;
uses
verbose,systems,cutils,
rgobj,
defutil,symsym;
defutil,symsym,symtable;
function tarmparamanager.get_volatile_registers_int(calloption : tproccalloption):tcpuregisterset;
@ -202,10 +202,75 @@ unit cpupara;
function tarmparamanager.ret_in_param(def : tdef;calloption : tproccalloption) : boolean;
var
i: longint;
sym: tsym;
fpufield: boolean;
begin
case def.typ of
recorddef:
result:=def.size>4;
begin
result:=def.size>4;
if not result and
(target_info.abi in [abi_default,abi_armeb]) then
begin
{ in case of the old ARM abi (APCS), a struct is returned in
a register only if it is simple. And what is a (non-)simple
struct:
"A non-simple type is any non-floating-point type of size
greater than one word (including structures containing only
floating-point fields), and certain single-word structured
types."
(-- ARM APCS documentation)
So only floating point types or more than one word ->
definitely non-simple (more than one word is already
checked above). This includes unions/variant records with
overlaid floating point and integer fields.
Smaller than one word struct types are simple if they are
"integer-like", and:
"A structure is termed integer-like if its size is less than
or equal to one word, and the offset of each of its
addressable subfields is zero."
(-- ARM APCS documentation)
An "addressable subfield" is a field of which you can take
the address, which in practive means any non-bitfield.
In Pascal, there is no way to express the difference that
you can have in C between "char" and "int :8". In this
context, we use the fake distinction that a type defined
inside the record itself (such as "a: 0..255;") indicates
a bitpacked field while a field using a different type
(such as "a: byte;") is not.
}
for i:=0 to trecorddef(def).symtable.SymList.count-1 do
begin
sym:=tsym(trecorddef(def).symtable.SymList[i]);
if sym.typ<>fieldvarsym then
continue;
{ bitfield -> ignore }
if (trecordsymtable(trecorddef(def).symtable).usefieldalignment=bit_alignment) and
(tfieldvarsym(sym).vardef.typ in [orddef,enumdef]) and
(tfieldvarsym(sym).vardef.owner.defowner=def) then
continue;
{ all other fields must be at offset zero }
if tfieldvarsym(sym).fieldoffset<>0 then
begin
result:=true;
exit;
end;
{ floating point field -> also by reference }
if tfieldvarsym(sym).vardef.typ=floatdef then
begin
result:=true;
exit;
end;
end;
end;
end;
procvardef:
if not tprocvardef(def).is_addressonly then
result:=true