[all-commits] [llvm/llvm-project] 3092b7: [mlir][vector] Refactor WarpOpScfForOp to support ...

[Charitha Saumya via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3092b765ba0b2d20bd716944dda86ea8e4ad12e3
      https://github.com/llvm/llvm-project/commit/3092b765ba0b2d20bd716944dda86ea8e4ad12e3
  Author: Charitha Saumya <136391709+charithaintc at users.noreply.github.com>
  Date:   2025-07-11 (Fri, 11 Jul 2025)

  Changed paths:
    M mlir/lib/Dialect/Vector/Transforms/VectorDistribute.cpp
    M mlir/lib/Dialect/XeGPU/Transforms/XeGPUSubgroupDistribute.cpp
    M mlir/test/Dialect/Vector/vector-warp-distribute.mlir

  Log Message:
  -----------
  [mlir][vector] Refactor WarpOpScfForOp to support unused or swapped forOp results. (#147620)

Current implementation generates incorrect code or crashes in the
following valid cases.

1. At least one of the for op results are not yielded by the warpOp.
Example:
```
%0 = gpu.warp_execute_on_lane_0(%arg0)[32] -> (vector<4xf32>) {
    ....
    %3:2 = scf.for %arg3 = %c0 to %c128 step %c1 iter_args(%arg4 = %ini, %arg5 = %ini1) -> (vector<128xf32>, vector<128xf32>) {
      
      %1  = ...
      %acc = ....
      scf.yield %acc, %1 : vector<128xf32>, vector<128xf32>
    }
    gpu.yield %3#0 : vector<128xf32> // %3#1 is not used but can not be removed as dead code (loop carried).
  }
  "some_use"(%0) : (vector<4xf32>) -> ()
  return
```
2. Enclosing warpOp yields the forOp results in different order compared
to the forOp results.
Example:
```
  %0:3 = gpu.warp_execute_on_lane_0(%arg0)[32] -> (vector<4xf32>, vector<4xf32>, vector<8xf32>) {
    ....
    %3:3 = scf.for %arg3 = %c0 to %c128 step %c1 iter_args(%arg4 = %ini1, %arg5 = %ini2, %arg6 = %ini3) -> (vector<256xf32>, vector<128xf32>, vector<128xf32>) {
      .....
      scf.yield %acc1, %acc2, %acc3 : vector<256xf32>, vector<128xf32>, vector<128xf32>
    }
    gpu.yield %3#2, %3#1, %3#0 : vector<128xf32>, vector<128xf32>, vector<256xf32> // swapped order
  }
  "some_use_1"(%0#0) : (vector<4xf32>) -> ()
  "some_use_2"(%0#1) : (vector<4xf32>) -> ()
  "some_use_3"(%0#2) : (vector<8xf32>) -> ()

```



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