[Mlir-commits] [mlir] [mlir][affine]introduce AffineSymbol trait and use it for using gpu.threadid op in the inner loops. (PR #118478)

[Uday Bondhugula]

bondhugula wrote:

> Why does the operand of such an Op also need to be a symbol?
This is key - otherwise, you are generating SSA values that are functions of dimensional values like loop IVs and those are exactly the opposite of symbols. For eg., an `affine.apply` is a pure operation - when it takes dimensional values, it'll generate a dimensional value, not symbolic. So the pure op should have zero or more symbolic operands.

https://github.com/llvm/llvm-project/pull/118478