Hi!
I'd like to do this myself but I have to dig into clang only for this wich takes some
time therefore I'd like to ask if someone is already is working on it (or wants to do it 
:
for c, the cast operator is extended to vectors (opencl):
(int)(1)
(int4)(1, 2, 3, 4)
for c++ the same could be done:
int(1)
int4(1, 2, 3, 4)
I use this variant since it can be emulated with c++ classes when no vector
extensions are available.
Will it be supported in the near future?
-Jochen
This is already supported with -faltivec, you can enable the LangOptions flag to get this.
-Chris
Hi!
This is already supported with -faltivec, you can enable the LangOptions flag to get this.
Unfortunately I didn't get it to work.
I have langOptions.AltiVec = 1; and I tried
typedef __vector float float4;
and
typedef float __attribute__((ext_vector_type(4))) float4;
I get this error:
testc.cpp:51:23:{51:14-51:33}: error: function-style cast to a builtin type can
only take one argument
float4 b = float4(1, 2, 3, 4);
- Jochen
This works for me:
$ cat t.c
void foo() {
vector float x;
x = (vector float)(1,2,3,4);
}
$ clang -cc1 t.c -fsyntax-only -faltivec
This works for me:
$ cat t.c
void foo() {
vector float x;
x = (vector float)(1,2,3,4);
}
$ clang -cc1 t.c -fsyntax-only -faltivec
Yes I know that this works. It's the c-like extension of the
cast operator to vectors, but in contrast I'd like to have
a c++-like extension of the function style cast:
int(1)
int4(1, 2, 3, 4)
-Jochen
Do other compilers support this syntax? (e.g., GCC)?
- Doug
int(1)
int4(1, 2, 3, 4)
Do other compilers support this syntax? (e.g., GCC)?
Cg, glsl and hlsl support it.
- Jochen
We do not aim to implement those languages in clang.
-Chris
Cg, glsl and hlsl support it.
We do not aim to implement those languages in clang.
I do not expect this, but will a patch for only the function style constructors
be accepted into mainline?
I think it's a natural extension of c++ syntax to vectors.
-Jochen
If you're okay with accepting it only in C++, I think it's a reasonable extension.
John.
In my opinion, there is no reason to do this. If you want C++ syntax to do this, define your_float4 as a struct with a constructor. There is already too much needless diversity in vector initialization, and C++'0x may add a whole new world of pain here.
-Chris
If you're okay with accepting it only in C++, I think it's a reasonable extension.
of course only in c++ mode (like int(1) also only works in c++ mode)
- Jochen
In my opinion, there is no reason to do this. If you want C++ syntax to do this, define your_float4 as a struct with a constructor. There is already too much needless diversity in vector initialization, and C++'0x may add a whole new world of pain here.
Then I can keep my current implementation that does not use vectors and use an auto-vectorization
pass. By the way what is the current state of the art on this topic?
But maybe I add the function style constructor to my local copy since not having it raises other
questions like default-initialization:
struct Foo
{
Foo() : x(), y() {}
int x;
int4 y;
};
If I get it working I will ask again
- Jochen
Hi!
just to capture the current state of c++ style vector support I made a little test:
struct Foo
{
Foo(int) : x() {} // works
Foo(float f) : x(f) {} // works
Foo(float4 x) : x(x) {} // works
Foo() : x(1, 2, 3, 4) {} // error: excess elements in scalar initializer
float4 bar1() {return float4();} // works
float4 bar2() {return float4(f);} // works
float4 bar3() {return float4(x);} // works
float4 bar4() {return float4(1, 2, 3, 4);} // error: function-style cast to a builtin type can only take one argument
float f;
float4 x;
};
I only checked if the statements compile.
-Jochen
Looks right to me!
-Chris
while being allowed to write float4(1,2,3,4) would be deluxe-support that
I know from graphics-centric compilers I found another way: e.g.
float4 makeFloat4(float a, float b, float c, float d){return (float4)(a, b, c, d);}
this can look the same from the outside if no vector support is available and
float4 is a struct with no constructors.
-Jochen
Hi!
while playing with vectors I get this error for int. it works for float:
typedef int __attribute__((ext_vector_type(4))) int4;
int4 foo = (int4)(1, 2, 3, 4);
testc.cpp:72:13:{72:13-72:19}: error: C-style cast from scalar 'int' to vector
'int4' of different size
int4 foo = (int4)(1, 2, 3, 4);
-Jochen