Change the ASR representation of ArrayConstant

[certik]

Currently ArrayConstant contains a list of individual constants, like RealConstant.

Instead, it should contain a type (that includes kind) of the element, shape, and then a pointer to contiguous data. This will be fast, and automatically enforce all the things we care about:

• That ArrayConstant only contains constants
• That all constants it contains have the same type and kind
• That it doesn't point to any other node by a mistake

[Pranavchiku]

I am not exactly sure of how ASR definition shall look like, if you can post it, it will be really helpful.

[certik]

Maybe something like this:

--- a/src/libasr/ASR.asdl
+++ b/src/libasr/ASR.asdl
@@ -139,7 +139,7 @@ expr
     | Var(symbol v)
     | FunctionParam(int param_number, ttype type, expr? value)
     | ArrayConstructor(expr* args, ttype type, expr? value, arraystorage storage_format)
-    | ArrayConstant(expr* args, ttype type, arraystorage storage_format)
+    | ArrayConstant(ttype type, int* data, arraystorage storage_format)
     | ArrayItem(expr v, array_index* args, ttype type, arraystorage storage_format, expr? value)
     | ArraySection(expr v, array_index* args, ttype type, expr? value)
     | ArraySize(expr v, expr? dim, ttype type, expr? value)

This should generate n_data and m_data pointer. Although we might not support int*. So maybe we need to introduce a new intrinsic type in asdl for this.

At the C++ side, it should be length and pointer to data. Maybe we can use ArrayConstant(ttype type, string data, arraystorage storage_format), which might work, as I think strings are represented by a length and a pointer to data, which is exactly what we need here. We can have 0 in there, but I think it might work.

[certik]

Once this works, we can then do: #3203 (comment)

[certik]

@Pranavchiku I forgot about this issue: I think now is a good time to get this fixed. Let's wrap up stdlib, and then fix this.

[Pranavchiku]

Yes, perfect.

[Pranavchiku]

I have a small question ( maybe things are not clear to me yet ), how can we represent ASR::expr_t** args using char* ( string )?

[certik]

Are you asking how to implement ArrayConstant for an array of strings?

[Pranavchiku]

I think I have it, char* data = (char *) args; will do the trick, where ASR::expr_t** args