llvm dev - Aug 2007 - [LLVMdev] Adding custom operation intrinsic for ASIP architectures.

Hi,

I was talking with aKor in #llvm how we could implement custom operation 
support for our ASIP architecture. We came into solution that the best 
way would be to write new custom operation intrinsic and optimization 
pass for raising certain type of function calls to those intrinsics 
(similar to raising mallocs).

Basically our custom operation are like calls, with operand name and 
multiple inputs and outputs. e.g. C code:
__llvm__custom_op_add(a,b,c) would be raised to customop add(i32 %tmp1, 
i32 %tmp24 , i32 %tmp25). Those "__llvm__custom_op_" prefixed function
will not have function body, but pure declarations in C code level.

Comments are welcome, especially if there anyone else, that needs this 
kind of functionality or if people has already implemented something 
similar.

Mikael Lepistö

On Tuesday 31 July 2007 06:58, Mikael Lepistö wrote:
> I was talking with aKor in #llvm how we could implement custom operation
> support for our ASIP architecture. We came into solution that the best
> way would be to write new custom operation intrinsic and optimization
> pass for raising certain type of function calls to those intrinsics
> (similar to raising mallocs).
>
> Basically our custom operation are like calls, with operand name and
> multiple inputs and outputs. e.g. C code:
> __llvm__custom_op_add(a,b,c) would be raised to customop add(i32 %tmp1,
> i32 %tmp24 , i32 %tmp25). Those "__llvm__custom_op_" prefixed
function
> will not have function body, but pure declarations in C code level.
Yes, this is very useful.  Can we somehow integrate this into tblgen so that
targets can declare intrinsics they are interested in capturing and map them
to machine instruction sequences?  I think a lot of architectures have need
for stuff like this and I would hate for a solution that only addresses those
needs in a piecemeal fashion.

                                                -Dave

On Tue, 31 Jul 2007, [ISO-8859-1] Mikael Lepist� wrote:
> I was talking with aKor in #llvm how we could implement custom operation
> support for our ASIP architecture. We came into solution that the best
> way would be to write new custom operation intrinsic and optimization
> pass for raising certain type of function calls to those intrinsics
> (similar to raising mallocs).
>
> Basically our custom operation are like calls, with operand name and
> multiple inputs and outputs. e.g. C code:
> __llvm__custom_op_add(a,b,c) would be raised to customop add(i32 %tmp1,
> i32 %tmp24 , i32 %tmp25). Those "__llvm__custom_op_" prefixed
function
> will not have function body, but pure declarations in C code level.
>
> Comments are welcome, especially if there anyone else, that needs this
> kind of functionality or if people has already implemented something
> similar.
Sure, this works.  This is exactly the idea of the builtin functions in 
GCC.  For example, in SSE, the __builtin_ia32_movntps function does a 
nontemporal store.

To answer David's question, we already have direct support for this in 
tblgen, for example, include/llvm/IntrinsicsX86.td contains:

let TargetPrefix = "x86" in {  // All intrinsics start with
"llvm.x86.".
   def int_x86_sse_movnt_ps :
GCCBuiltin<"__builtin_ia32_movntps">,
               Intrinsic<[llvm_void_ty, llvm_ptr_ty,
                          llvm_v4f32_ty], [IntrWriteMem]>;
}

and lib/Target/X86/X86InstrSSE.td contains:

def MOVNTPSmr : PSI<0x2B, MRMDestMem, (outs), (ins i128mem:$dst, VR128:$src),
                     "movntps {$src, $dst|$dst, $src}",
                     [(int_x86_sse_movnt_ps addr:$dst, VR128:$src)]>;

There is corresponding code in llvm-gcc to tell GCC how to handle this 
builtin.  Is this what you're looking for?

-Chris

-- 
http://nondot.org/sabre/
http://llvm.org/

Chris Lattner wrote:
> On Tue, 31 Jul 2007, [ISO-8859-1] Mikael Lepist� wrote:
>> I was talking with aKor in #llvm how we could implement custom
operation
>> support for our ASIP architecture. We came into solution that the best
>> way would be to write new custom operation intrinsic and optimization
>> pass for raising certain type of function calls to those intrinsics
>> (similar to raising mallocs).
>>
>> Basically our custom operation are like calls, with operand name and
>> multiple inputs and outputs. e.g. C code:
>> __llvm__custom_op_add(a,b,c) would be raised to customop add(i32 %tmp1,
>> i32 %tmp24 , i32 %tmp25). Those "__llvm__custom_op_" prefixed
function
>> will not have function body, but pure declarations in C code level.
>>
>> Comments are welcome, especially if there anyone else, that needs this
>> kind of functionality or if people has already implemented something
>> similar.
>
> Sure, this works. This is exactly the idea of the builtin functions in 
> GCC. For example, in SSE, the __builtin_ia32_movntps function does a 
> nontemporal store.
>
> To answer David's question, we already have direct support for this in 
> tblgen, for example, include/llvm/IntrinsicsX86.td contains:
>
> let TargetPrefix = "x86" in { // All intrinsics start with
"llvm.x86.".
> def int_x86_sse_movnt_ps :
GCCBuiltin<"__builtin_ia32_movntps">,
> Intrinsic<[llvm_void_ty, llvm_ptr_ty,
> llvm_v4f32_ty], [IntrWriteMem]>;
> }
>
> and lib/Target/X86/X86InstrSSE.td contains:
>
> def MOVNTPSmr : PSI<0x2B, MRMDestMem, (outs), (ins i128mem:$dst, 
> VR128:$src),
> "movntps {$src, $dst|$dst, $src}",
> [(int_x86_sse_movnt_ps addr:$dst, VR128:$src)]>;
>
> There is corresponding code in llvm-gcc to tell GCC how to handle this 
> builtin. Is this what you're looking for?
>
Yes this is more or less, what we are looking for, except we need 
variable arguments for out intrinsic. I assume that it can be achieved 
by using llvm_vararg_ty as a argument type?

Is there need to make changes to llvm-gcc for supporting new GCCBuiltin 
types that I define or are all of them automatically converted to 
intrinsics on gcc side?

Mikael Lepistö