| Issue |
115653
|
| Summary |
Bugs in patterns under `populateVectorNarrowTypeEmulationPatterns` (1D vs 2D)
|
| Labels |
mlir:vector
|
| Assignees |
|
| Reporter |
banach-space
|
All patterns in populateVectorNarrowTypeEmulationPatterns currently assume a 1-D vector load/store rather than an n-D vector load/store. This assumption is evident in ConvertVectorTransferRead, for example, [here](https://github.com/llvm/llvm-project/blob/58a17e1bbc54357385d0b89cfc5635e402c31ef6/mlir/lib/Dialect/Vector/Transforms/VectorEmulateNarrowType.cpp#L670-L676):
```cpp
auto newRead = rewriter.create<vector::TransferReadOp>(
loc, VectorType::get(numElements, newElementType), adaptor.getSource(),
getValueOrCreateConstantIndexOp(rewriter, loc, linearizedIndices),
newPadding);
auto bitCast = rewriter.create<vector::BitCastOp>(
loc, VectorType::get(numElements * scale, oldElementType), newRead);
```
Both invocations of `VectorType::get()` here generate a 1-D vector.
Attempts to use these patterns with more generic cases, such as 2-D vectors, fail. For example, trying to cast the following 2-D case to `i32`:
```mlir
func.func @vector_maskedload_2d_i8_negative(
%idx1: index,
%idx2: index,
%num_elems: index,
%passthru: vector<2x4xi8>) -> vector<2x4xi8> {
%0 = memref.alloc() : memref<3x4xi8>
%mask = vector.create_mask %num_elems, %num_elems : vector<2x4xi1>
%1 = vector.maskedload %0[%idx1, %idx2], %mask, %passthru :
memref<3x4xi8>, vector<2x4xi1>, vector<2x4xi8> into vector<2x4xi8>
return %1 : vector<2x4xi8>
}
```
leads to the following error:
```bash
error: 'vector.bitcast' op failed to verify that all of {source, result} have same rank
%1 = vector.maskedload %0[%idx1, %idx2], %mask, %passthru :
^
```
Here’s the mlir-opt invocation used:
```bash
mlir-opt --test-emulate-narrow-int="arith-compute-bitwidth=1 memref-load-bitwidth=32"
```
For further context, I’ve included a full list of reproductions as tests in this PR:
* https://github.com/llvm/llvm-project/pull/115612.
As a temporary workaround, I suggest restricting these patterns to 1-D vectors.
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