Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 03/01/2016 11:43 AM, Michael Matz wrote: Hi, On Mon, 29 Feb 2016, Jason Merrill wrote: Also this insistence that all of "trivially copyable" is already quite nicely specified in the C++ ABI is still not really relevant because C++ _is not the only language out there_. I'm not sure how

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Mon, 29 Feb 2016, Jason Merrill wrote: > > Also this insistence that all of "trivially copyable" is already quite > > nicely specified in the C++ ABI is still not really relevant because > > C++ _is not the only language out there_. I'm not sure how often I > > have to repeat this

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Fri, 26 Feb 2016, H.J. Lu wrote: > >> It is clear to me now. Let's go with > >> > >> --- > >> An empty type is a type where it and all of its subobjects (recursively) > >> are of class, structure, union, or array type. No memory slot nor > >> register should be used to pass or return an

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 23, 2016 at 5:14 PM, Richard Smith wrote: > On Tue, Feb 23, 2016 at 8:28 AM, H.J. Lu wrote: >> On Tue, Feb 23, 2016 at 8:15 AM, Michael Matz wrote: >>> Hi, >>> >>> On Tue, 23 Feb 2016, H.J. Lu wrote: >>> I thought

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 23, 2016 at 8:28 AM, H.J. Lu wrote: > On Tue, Feb 23, 2016 at 8:15 AM, Michael Matz wrote: >> Hi, >> >> On Tue, 23 Feb 2016, H.J. Lu wrote: >> >>> I thought >>> >>> --- >>> An empty type is a type where it and all of its subobjects (recursively) >>>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 23, 2016 at 8:15 AM, Michael Matz wrote: > Hi, > > On Tue, 23 Feb 2016, H.J. Lu wrote: > >> I thought >> >> --- >> An empty type is a type where it and all of its subobjects (recursively) >> are of class, structure, union, or array type. >> --- >> >> excluded >> >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 23, 2016 at 7:30 AM, Michael Matz wrote: > Hi, > > On Tue, 23 Feb 2016, H.J. Lu wrote: > >> > --- >> > An empty type is a type where it and all of its subobjects (recursively) >> > are of class, structure, union, or array type. No memory slot nor >> > register should be

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Tue, 23 Feb 2016, H.J. Lu wrote: > > --- > > An empty type is a type where it and all of its subobjects (recursively) > > are of class, structure, union, or array type. No memory slot nor > > register should be used to pass or return an object of empty type that's > > trivially copyable.

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 22, 2016 at 4:50 AM, Michael Matz wrote: > Hi, > > On Sat, 20 Feb 2016, Richard Smith wrote: > >> > An empty type is a type where it and all of its subobjects >> > (recursively) are of class, structure, union, or array type. >> > >> > doesn't cover "trivially-copyable".

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Sat, 20 Feb 2016, Richard Smith wrote: > > An empty type is a type where it and all of its subobjects > > (recursively) are of class, structure, union, or array type. > > > > doesn't cover "trivially-copyable". > > That's correct. Whether a type is trivially copyable is unrelated to >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Fri, 19 Feb 2016, Richard Smith wrote: > >> > The trivially copyable is gone again. Why is it not necessary? > >> > >> The C++ ABI doesn't defer to the C psABI for types that aren't > >> trivially-copyable. See > >> http://mentorembedded.github.io/cxx-abi/abi.html#normal-call > > > >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sat, Feb 20, 2016 at 10:48 PM, Richard Smith wrote: > On 20 Feb 2016 10:01 p.m., "H.J. Lu" wrote: >> >> On Sat, Feb 20, 2016 at 9:47 PM, Richard Smith >> wrote: >> > On 20 Feb 2016 6:54 p.m., "H.J. Lu"

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 20 Feb 2016 10:01 p.m., "H.J. Lu" wrote: > > On Sat, Feb 20, 2016 at 9:47 PM, Richard Smith wrote: > > On 20 Feb 2016 6:54 p.m., "H.J. Lu" wrote: > >> > >> On Sat, Feb 20, 2016 at 4:57 PM, Matthijs van Duin > >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sat, Feb 20, 2016 at 9:47 PM, Richard Smith wrote: > On 20 Feb 2016 6:54 p.m., "H.J. Lu" wrote: >> >> On Sat, Feb 20, 2016 at 4:57 PM, Matthijs van Duin >> wrote: >> > On 20 February 2016 at 23:35, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 20 Feb 2016 6:54 p.m., "H.J. Lu" wrote: > > On Sat, Feb 20, 2016 at 4:57 PM, Matthijs van Duin > wrote: > > On 20 February 2016 at 23:35, H.J. Lu wrote: > >> Can a compiler tell if a copy constructor or destructor is

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sat, 20 Feb 2016, H.J. Lu wrote: On Fri, Feb 19, 2016 at 1:07 PM, Richard Smith wrote: On Fri, Feb 19, 2016 at 5:35 AM, Michael Matz wrote: Hi, On Thu, 18 Feb 2016, Richard Smith wrote: An empty type is a type where it and all of its subobjects

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 20 February 2016 at 23:35, H.J. Lu wrote: > Can a compiler tell if a copy constructor or destructor is trivial > from the class declaration without function body? Yes, the mere presence of the declaration suffices to render it non-trivial (unless explicitly declared "=

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sat, Feb 20, 2016 at 11:40 AM, Matthijs van Duin wrote: > On 20 February 2016 at 20:34, H.J. Lu wrote: >> Is there a class, which meets the above definition, with a member function >> which can't be passed without a memory slot or a register? >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 20 February 2016 at 20:34, H.J. Lu wrote: > Is there a class, which meets the above definition, with a member function > which can't be passed without a memory slot or a register? The EmptyInt class in my first post in this thread. It has no non-static data members, has

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sat, Feb 20, 2016 at 10:50 AM, Matthijs van Duin wrote: > On 20 February 2016 at 18:55, H.J. Lu wrote: >> struct dummy0 >> { >> }; >> >> struct dummy >> { >> dummy0 d[20]; >> >> dummy0 * foo (int i); >> }; >> >> dummy0 * >> dummy::foo (int

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 20 February 2016 at 18:55, H.J. Lu wrote: > struct dummy0 > { > }; > > struct dummy > { > dummy0 d[20]; > > dummy0 * foo (int i); > }; > > dummy0 * > dummy::foo (int i) > { > return [i]; > } > > dummy0 * > bar (dummy d, int i) > { > return d.foo (i); > } 1. This

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Fri, Feb 19, 2016 at 1:07 PM, Richard Smith wrote: > On Fri, Feb 19, 2016 at 5:35 AM, Michael Matz wrote: >> Hi, >> >> On Thu, 18 Feb 2016, Richard Smith wrote: >> >>> >> An empty type is a type where it and all of its subobjects >>> >> (recursively) are

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Fri, Feb 19, 2016 at 5:35 AM, Michael Matz wrote: > Hi, > > On Thu, 18 Feb 2016, Richard Smith wrote: > >> >> An empty type is a type where it and all of its subobjects >> >> (recursively) are of class, structure, union, or array type. No >> >> memory slot nor register should be

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Fri, Feb 19, 2016 at 11:03 AM, Matthijs van Duin wrote: > On 19 February 2016 at 14:35, Michael Matz wrote: >> struct S { >> S() {something();} >> }; >> >> would be an empty type, and that's not what we want. > > Why not? The default constructor is

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 19 February 2016 at 14:35, Michael Matz wrote: > struct S { > S() {something();} > }; > > would be an empty type, and that's not what we want. Why not? The default constructor is never invoked as part of passing such an object around. Its copy constructor is a nop and requires

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 19 February 2016 at 16:27, H.J. Lu wrote: > We want to include static member functions and exclude non-static member > functions. > There's no reason to disallow non-static member functions in general; they have no impact on being trivially copyable or not, only the

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Fri, Feb 19, 2016 at 5:35 AM, Michael Matz wrote: > Hi, > > On Thu, 18 Feb 2016, Richard Smith wrote: > >> >> An empty type is a type where it and all of its subobjects >> >> (recursively) are of class, structure, union, or array type. No >> >> memory slot nor register should be

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Thu, 18 Feb 2016, H.J. Lu wrote: > >> An empty type is a type where it and all of its subobjects > >> (recursively) are of class, structure, union, or array type. No > >> memory slot nor register should be used to pass or return an object > >> of empty type. > > > > The trivially

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Thu, 18 Feb 2016, Richard Smith wrote: > >> An empty type is a type where it and all of its subobjects > >> (recursively) are of class, structure, union, or array type. No > >> memory slot nor register should be used to pass or return an object > >> of empty type. > > > > The

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 18, 2016 at 6:35 AM, Michael Matz wrote: > Hi, > > On Tue, 16 Feb 2016, H.J. Lu wrote: > >> Here is the new definition: >> >> An empty type is a type where it and all of its subobjects (recursively) >> are of class, structure, union, or array type. No memory slot nor >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 18, 2016 at 6:35 AM, Michael Matz wrote: > Hi, > > On Tue, 16 Feb 2016, H.J. Lu wrote: > >> Here is the new definition: >> >> An empty type is a type where it and all of its subobjects (recursively) >> are of class, structure, union, or array type. No memory slot nor >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Tue, 16 Feb 2016, H.J. Lu wrote: > Here is the new definition: > > An empty type is a type where it and all of its subobjects (recursively) > are of class, structure, union, or array type. No memory slot nor > register should be used to pass or return an object of empty type. The

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 3:36 PM, Richard Smith wrote: > On Tue, Feb 16, 2016 at 1:48 PM, H.J. Lu wrote: >> On Tue, Feb 16, 2016 at 1:45 PM, Richard Smith wrote: >>> On Tue, Feb 16, 2016 at 1:21 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 1:45 PM, Richard Smith wrote: > On Tue, Feb 16, 2016 at 1:21 PM, H.J. Lu wrote: >> On Tue, Feb 16, 2016 at 1:15 PM, Richard Smith wrote: >>> On Tue, Feb 16, 2016 at 1:10 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 1:15 PM, Richard Smith wrote: > On Tue, Feb 16, 2016 at 1:10 PM, H.J. Lu wrote: >> On Tue, Feb 16, 2016 at 1:02 PM, Richard Smith wrote: >>> On Tue, Feb 16, 2016 at 12:25 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 1:10 PM, H.J. Lu wrote: > On Tue, Feb 16, 2016 at 1:02 PM, Richard Smith wrote: >> On Tue, Feb 16, 2016 at 12:25 PM, H.J. Lu wrote: >>> On Tue, Feb 16, 2016 at 12:22 PM, Richard Smith

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 1:02 PM, Richard Smith wrote: > On Tue, Feb 16, 2016 at 12:25 PM, H.J. Lu wrote: >> On Tue, Feb 16, 2016 at 12:22 PM, Richard Smith >> wrote: >>> On Tue, Feb 16, 2016 at 10:24 AM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 12:25 PM, H.J. Lu wrote: > On Tue, Feb 16, 2016 at 12:22 PM, Richard Smith wrote: >> On Tue, Feb 16, 2016 at 10:24 AM, H.J. Lu wrote: >>> >>> On Fri, Feb 12, 2016 at 11:39 AM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 12:22 PM, Richard Smith wrote: > On Tue, Feb 16, 2016 at 10:24 AM, H.J. Lu wrote: >> >> On Fri, Feb 12, 2016 at 11:39 AM, H.J. Lu wrote: >> > On Fri, Feb 12, 2016 at 6:58 AM, Matthijs van Duin >> >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 16, 2016 at 10:24 AM, H.J. Lu wrote: > > On Fri, Feb 12, 2016 at 11:39 AM, H.J. Lu wrote: > > On Fri, Feb 12, 2016 at 6:58 AM, Matthijs van Duin > > wrote: > >> On 11 February 2016 at 16:31, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Fri, Feb 12, 2016 at 11:39 AM, H.J. Lu wrote: > On Fri, Feb 12, 2016 at 6:58 AM, Matthijs van Duin > wrote: >> On 11 February 2016 at 16:31, H.J. Lu wrote: >>> struct A { >>> static void foo (void) (); >>> static int xxx;

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 11 February 2016 at 16:31, H.J. Lu wrote: > struct A { > static void foo (void) (); > static int xxx; > }; What about it? It's an empty struct. (And it declares a function and a variable in the namespace of A, which however do not have any relevant impact here.)

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 11, 2016 at 2:47 AM, Matthijs van Duin wrote: > On 8 February 2016 at 22:40, H.J. Lu wrote: >> "empty type". An empty type is either an array of empty types or a >> class type where every member is of empty type. > > Note that the term

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 11, 2016 at 6:30 AM, Michael Matz wrote: > Hi, > > On Thu, 11 Feb 2016, Jonathan Wakely wrote: > >> On 11 February 2016 at 12:40, Matthijs van Duin wrote: >> > You never define "POD for the purposes of layout", and I can only >> > interpret it as being equivalent to

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Thu, 11 Feb 2016, H.J. Lu wrote: > Any suggestions on new wording, something like > > 1. "class type". A class type is a structure, union or C++ class. > 2. "empty type". An empty type is a type where it and all of its > subobjects are of class or array type. > > Does it cover >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Hi, On Thu, 11 Feb 2016, Jonathan Wakely wrote: > On 11 February 2016 at 12:40, Matthijs van Duin wrote: > > You never define "POD for the purposes of layout", and I can only > > interpret it as being equivalent to "standard-layout". > > As Richard pointed out, it's defined in the C++ ABI.

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 11, 2016 at 4:40 AM, Matthijs van Duin wrote: > On 11 February 2016 at 11:53, H.J. Lu wrote: >> Since this isn't Plain Old Data (POD) for the purposes of layout, it >> isn't covered by my proposal for psABI. I leave this to C++ ABI. >

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 11 February 2016 at 12:40, Matthijs van Duin wrote: > You never define "POD for the purposes of layout", and I can only > interpret it as being equivalent to "standard-layout". As Richard pointed out, it's defined in the C++ ABI. ___ cfe-commits

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 22:40, H.J. Lu wrote: > "empty type". An empty type is either an array of empty types or a > class type where every member is of empty type. Note that the term "empty type" is commonly used in type theory to denote a (or the) type with no values. The

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 11 February 2016 at 11:53, H.J. Lu wrote: > Since this isn't Plain Old Data (POD) for the purposes of layout, it > isn't covered by my proposal for psABI. I leave this to C++ ABI. You never define "POD for the purposes of layout", and I can only interpret it as being

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 11 February 2016 at 15:00, H.J. Lu wrote: > I intentionally exclude C++ specific features in my propose. Yet you use a definition from the Itanium C++ ABI which itself depends on multiple definitions in a particular version of the C++ standard, which depend on C++

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 11, 2016 at 6:18 AM, Matthijs van Duin wrote: > On 11 February 2016 at 15:00, H.J. Lu wrote: >> I intentionally exclude C++ specific features in my propose. > > Yet you use a definition from the Itanium C++ ABI which itself depends > on

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 11 February 2016 at 13:58, H.J. Lu wrote: > "POD for the purpose of layout" is defined in the Itanium C++ ABI here: > > http://mentorembedded.github.io/cxx-abi/abi.html#definitions Sorry, I overlooked that. I still stand by my viewpoint however that triviality of copying

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Thu, Feb 11, 2016 at 6:54 AM, Michael Matz wrote: > Hi, > > On Thu, 11 Feb 2016, H.J. Lu wrote: > >> Any suggestions on new wording, something like >> >> 1. "class type". A class type is a structure, union or C++ class. >> 2. "empty type". An empty type is a type where it and

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

To avoid depending again on precise wording of definitions in C++ standard it may be worth being explicit about the requirement to be trivially copyable *and* destructible, since although the former implies the latter in the C++ standard this is not obvious from the terminology (although you also

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Tue, Feb 9, 2016 at 6:45 AM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 3:28 PM, Richard Smith wrote: >> On Mon, Feb 8, 2016 at 3:01 PM, H.J. Lu wrote: >>> On Mon, Feb 8, 2016 at 2:58 PM, Richard Smith

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 8:15 AM, Jonathan Wakely wrote: > On 8 February 2016 at 16:05, H.J. Lu wrote: >> My understanding is >> >> A type that is standard-layout means that it orders and packs its >> members in a way that is compatible with C. >> >> What is the corresponding

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 7:02 AM, Jonathan Wakely wrote: > On 8 February 2016 at 13:54, H.J. Lu wrote: >> On Sun, Feb 7, 2016 at 12:52 PM, H.J. Lu wrote: >> >> The standard-layout POD is well defined: >> >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 16:05, H.J. Lu wrote: > My understanding is > > A type that is standard-layout means that it orders and packs its > members in a way that is compatible with C. > > What is the corresponding compatible type in C? An empty structure, such as struct A. One of the requirements

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 7:59 AM, Jonathan Wakely wrote: > On 8 February 2016 at 15:42, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 7:02 AM, Jonathan Wakely >> wrote: >>> On 8 February 2016 at 13:54, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 15:42, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 7:02 AM, Jonathan Wakely wrote: >> On 8 February 2016 at 13:54, H.J. Lu wrote: >>> On Sun, Feb 7, 2016 at 12:52 PM, H.J. Lu wrote: >>> >>>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 13:54, H.J. Lu wrote: > On Sun, Feb 7, 2016 at 12:52 PM, H.J. Lu wrote: > > The standard-layout POD is well defined: > > https://en.wikipedia.org/wiki/C%2B%2B11#Modification_to_the_definition_of_plain_old_data > > Here is the

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sun, Feb 7, 2016 at 12:52 PM, H.J. Lu wrote: > On Sun, Feb 7, 2016 at 12:48 PM, Florian Weimer wrote: >> * H. J. Lu: >> I tested GCC 5.3.1 and Clang 3.5.0. GCC Clang s0 non-emptynon-empty s1 non-empty

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 7:59 AM, Jonathan Wakely wrote: >>> A type is a standard-layout type, or it isn't. >> >> How about "An empty record is standard-layout Plain Old Data (POD) >> type and ..."? > > That's redundant, all POD types are standard-layout types. > Apparently,

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 18:26, Jonathan Wakely wrote: > On 8 February 2016 at 17:58, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 7:59 AM, Jonathan Wakely >> wrote: > A type is a standard-layout type, or it isn't. How about "An empty record

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 18:31, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 10:30 AM, Jonathan Wakely > wrote: >> On 8 February 2016 at 18:26, Jonathan Wakely wrote: >>> On 8 February 2016 at 17:58, H.J. Lu wrote: On Mon, Feb 8,

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 17:58, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 7:59 AM, Jonathan Wakely wrote: A type is a standard-layout type, or it isn't. >>> >>> How about "An empty record is standard-layout Plain Old Data (POD) >>> type and ..."? >> >> That's redundant, all

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 10:30 AM, Jonathan Wakely wrote: > On 8 February 2016 at 18:26, Jonathan Wakely wrote: >> On 8 February 2016 at 17:58, H.J. Lu wrote: >>> On Mon, Feb 8, 2016 at 7:59 AM, Jonathan Wakely >>> wrote:

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 10:46 AM, Jonathan Wakely wrote: > On 8 February 2016 at 18:31, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 10:30 AM, Jonathan Wakely >> wrote: >>> On 8 February 2016 at 18:26, Jonathan Wakely

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On 8 February 2016 at 19:23, Richard Smith wrote: > "POD for the purpose of layout" is defined in the Itanium C++ ABI here: > > http://mentorembedded.github.io/cxx-abi/abi.html#definitions Thanks. So there's no problem using "POD for the purposes of layout", and the change to "POD for the

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 11:33 AM, Jonathan Wakely wrote: > On 8 February 2016 at 19:23, Richard Smith wrote: >> "POD for the purpose of layout" is defined in the Itanium C++ ABI here: >> >> http://mentorembedded.github.io/cxx-abi/abi.html#definitions > > Thanks. So there's

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 12:05 PM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 11:33 AM, Jonathan Wakely > wrote: > > On 8 February 2016 at 19:23, Richard Smith wrote: > >> "POD for the purpose of layout" is defined in the Itanium C++ ABI here: > >> > >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 12:38 PM, Richard Smith wrote: > On Mon, Feb 8, 2016 at 12:05 PM, H.J. Lu wrote: >> >> On Mon, Feb 8, 2016 at 11:33 AM, Jonathan Wakely >> wrote: >> > On 8 February 2016 at 19:23, Richard Smith wrote: >>

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 10:46 AM, Jonathan Wakely via cfe-commits < cfe-commits@lists.llvm.org> wrote: > On 8 February 2016 at 18:31, H.J. Lu wrote: > > On Mon, Feb 8, 2016 at 10:30 AM, Jonathan Wakely > wrote: > >> On 8 February 2016 at 18:26,

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:42 PM, Richard Smith wrote: > Do we really need an 'empty type' special case? > > The x86_64 psABI already seems clear that empty types with size <= 16 > are not passed at all. Following the algorithm in section 3.2.3, each > eightbyte is classified

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:46 PM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 2:35 PM, Richard Smith wrote: >> On Mon, Feb 8, 2016 at 1:40 PM, H.J. Lu wrote: >>> >>> On Mon, Feb 8, 2016 at 12:38 PM, Richard Smith

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:49 PM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 2:42 PM, Richard Smith wrote: >> Do we really need an 'empty type' special case? >> >> The x86_64 psABI already seems clear that empty types with size <= 16 >> are not passed at

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:51 PM, Richard Smith wrote: > On Mon, Feb 8, 2016 at 2:46 PM, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 2:35 PM, Richard Smith wrote: >>> On Mon, Feb 8, 2016 at 1:40 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:54 PM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 2:51 PM, Richard Smith wrote: >> On Mon, Feb 8, 2016 at 2:46 PM, H.J. Lu wrote: >>> On Mon, Feb 8, 2016 at 2:35 PM, Richard Smith

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:35 PM, Richard Smith wrote: > On Mon, Feb 8, 2016 at 1:40 PM, H.J. Lu wrote: >> >> On Mon, Feb 8, 2016 at 12:38 PM, Richard Smith wrote: >> > On Mon, Feb 8, 2016 at 12:05 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:58 PM, Richard Smith wrote: > On Mon, Feb 8, 2016 at 2:54 PM, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 2:51 PM, Richard Smith wrote: >>> On Mon, Feb 8, 2016 at 2:46 PM, H.J. Lu

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 1:40 PM, H.J. Lu wrote: > > On Mon, Feb 8, 2016 at 12:38 PM, Richard Smith wrote: > > On Mon, Feb 8, 2016 at 12:05 PM, H.J. Lu wrote: > >> > >> On Mon, Feb 8, 2016 at 11:33 AM, Jonathan Wakely

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Do we really need an 'empty type' special case? The x86_64 psABI already seems clear that empty types with size <= 16 are not passed at all. Following the algorithm in section 3.2.3, each eightbyte is classified as NO_CLASS, and thus is not passed. So the proposed change would only affect the

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 2:55 PM, Richard Smith wrote: > On Mon, Feb 8, 2016 at 2:49 PM, H.J. Lu wrote: >> On Mon, Feb 8, 2016 at 2:42 PM, Richard Smith wrote: >>> Do we really need an 'empty type' special case? >>> >>> The x86_64

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Mon, Feb 8, 2016 at 3:01 PM, H.J. Lu wrote: > On Mon, Feb 8, 2016 at 2:58 PM, Richard Smith wrote: >> On Mon, Feb 8, 2016 at 2:54 PM, H.J. Lu wrote: >>> On Mon, Feb 8, 2016 at 2:51 PM, Richard Smith

RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

Empty struct value is passed differently in C and C++ on Intel386 and x86-64. Different compilers use different calling conventions on the same platform: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60336 The same compiler behaves different on different platforms:

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sun, Feb 7, 2016 at 11:36 AM, H.J. Lu wrote: > On Sun, Feb 7, 2016 at 11:31 AM, Florian Weimer wrote: >> * H. J. Lu: >> >>> I am proposing to update Intel386, x86-64 and IA MCU psABIs to specify >>> how to pass/return empty struct: >>> >>> 1.

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

* H. J. Lu: >> I tested GCC 5.3.1 and Clang 3.5.0. >> >> GCC Clang >> s0 non-emptynon-empty >> s1 non-emptyempty >> s2 non-emptyempty >> s3 emptyempty >> s4 emptyempty >> s5 non-emptyempty >> >> I believe s3, s4, s5 are non-empty according

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

* H. J. Lu: >> Any syntactical array argument (at the C level) is should be passed as >> a pointer. The language appears to change that. > > I didn't use aggregate so that array is excluded here. > >> For 2., static members and non-data members do not count. > > They do count here. That is why

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sun, Feb 7, 2016 at 12:08 PM, Florian Weimer wrote: > * H. J. Lu: > >>> Any syntactical array argument (at the C level) is should be passed as >>> a pointer. The language appears to change that. >> >> I didn't use aggregate so that array is excluded here. >> >>> For 2.,

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sun, Feb 7, 2016 at 12:48 PM, Florian Weimer wrote: > * H. J. Lu: > >>> I tested GCC 5.3.1 and Clang 3.5.0. >>> >>> GCC Clang >>> s0 non-emptynon-empty >>> s1 non-emptyempty >>> s2 non-emptyempty >>> s3 emptyempty >>> s4 empty

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

On Sun, Feb 7, 2016 at 11:31 AM, Florian Weimer wrote: > * H. J. Lu: > >> I am proposing to update Intel386, x86-64 and IA MCU psABIs to specify >> how to pass/return empty struct: >> >> 1. "collection". A collection is a structure, union or C++ class. >> 2. "empty

Re: RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

* H. J. Lu: > I am proposing to update Intel386, x86-64 and IA MCU psABIs to specify > how to pass/return empty struct: > > 1. "collection". A collection is a structure, union or C++ class. > 2. "empty collection". An empty collection is: >a. A collection without member. Or >b. A