Extracting the int value of a function argument

MLIR
1

My function entry looks like this (%arg0: i32, %arg1: memref<?xi32>)

Block &entryBlock = func.getBody().front();
Value firstArg = entryBlock.getArgument(0);

I want to get the int value of %arg0 and create a memory space for it.
MemRefType inputMemType = MemRefType::get({size}, firstArgType);
But size needs to be an int value and I have no way of extracting the int value of %arg0.

2

I always fail with this approach. My functions never have a body. I first have to create a block and then I can walk over the arguments.

  mlir::Block *entryBlock = builder.createBlock(
      &fun.getBody(), {}, parameterTypes, parameterLocation);

  entryBlock->getArguments();
3

I am very confused by what you’re trying to achieve right now: you’re trying to build a memref type with a compile time constant size for the dimension, but at the same time you’re trying to get it from the function argument which is a dynamic value. Something is inconsistent here.
What you may want is a dynamic memref (the size is not known at compile time):

  auto dynamicBufferType =
      MemRefType::get(ShapedType::kDynamic, firstArgType);
4

Yes, the size of the memref is not known before compiling. I want to create a memref whose size is determined by the function parameter（%arg0）.

  auto dynamicBufferType =
      MemRefType::get(ShapedType::kDynamic, firstArgType);

A dynamic memref does not seem to be able to be related to the function parameter.

5

This would be based on the operation you use to create the memref, not the type, e.g. if you use memref.alloc it would look something like memref.alloc(%arg0) : memref<?xi32>

6

This isn’t gonna be encoded in the type system: the type system does not support directly dependent types (I think this is what you’re looking for here?)

However as @troggo mentioned, you can allocate a memref with the function argument as size, the type itself will erase this size information though.