I am trying to define a library in Ada (built on GNAT specifically) for x86 ISA extensions. (This question is specific to AVX/AVX2).

Here is some example code below:

-- 256-bit Vector of Single Precision Floating Point Numbers
type Vector_256_Float_32 is array (0 .. 7) of IEEE_Float_32 with
  Alignment => 32, Size => 256, Object_Size => 256;
pragma Machine_Attribute (Vector_256_Float_32, "vector_type");
pragma Machine_Attribute (Vector_256_Float_32, "may_alias");

-- 256-bit Vector of 32-bit Signed Integers
type Vector_256_Integer_32 is array (0 .. 7) of Integer_32 with
  Alignment => 32, Size => 256, Object_Size => 256;
pragma Machine_Attribute (Vector_256_Integer_32, "vector_type");
pragma Machine_Attribute (Vector_256_Integer_32, "may_alias");

-- 256-bit Vector of 32-bit Unsigned Integers
type Vector_256_Unsigned_32 is array (0 .. 7) of Unsigned_32 with
  Alignment => 32, Size => 256, Object_Size => 256;
pragma Machine_Attribute (Vector_256_Unsigned_32, "vector_type");
pragma Machine_Attribute (Vector_256_Unsigned_32, "may_alias");

function vblendvps
  (Left, Right, Mask : Vector_256_Float_32)
   return Vector_256_Float_32 with
  Inline_Always => True, Convention => Intrinsic, Import => True,
  External_Name => "__builtin_ia32_blendvps256";

For the sake of education, I want to know how to do this in assembly.

I have tried to define the vblendvps function using the Asm function from System.Machine_Code. However, as I am not knowledgeable about assembly programming, I am struggling to find resources on how to do this.

This is what I have so far:

with System.Machine_Code; use System.Machine_Code;

function vblendvps
(Left, Right, Mask : Vector_256_Float_32)
return Vector_256_Float_32
is
result : Vector_256_Float_32;
begin
Asm
(Template => "vblendvps %3, %0, %1, %2",
 Outputs  => Vector_256_Float_32'Asm_Output ("=g", result),
 Inputs   =>
   (Vector_256_Float_32'Asm_Input ("g", Left),
    Vector_256_Float_32'Asm_Input ("g", Right),
    Vector_256_Unsigned_32'Asm_Input ("g", Mask)));
return result;
end vblendvps;

When compiling the complete code, I get

Error: too many memory references for `vblendvps'

I believe this means that I need to move the arguments from memory to registers, but I am not sure. If there are some helpful references that explain every instruction, I would greatly appreciate that. (I had quite some trouble looking up the arguments to vblendvps).

My understanding is that the instruction is of the form (from ymm registers in my case)

vblendvps RESULT, LEFT, RIGHT, MASK

Please let me know how I would do this. Even if it is not in Ada, I'm sure I can figure out how to translate it.