| Issue |
134291
|
| Summary |
[mlir] -remove-dead-values generates invalid MLIR for affine.for with iter_args, which executes only once.
|
| Labels |
mlir
|
| Assignees |
|
| Reporter |
yyong120
|
To reproduce: `mlir-opt -remove-dead-values test.mlir`
`test.mlir`:
```
func.func @test_affine_for() {
%c1_i32 = arith.constant 1 : i32
%alloca = memref.alloca() : memref<16xi32>
%0 = affine.for %arg0 = 0 to 16 step 64 iter_args(%arg1 = %c1_i32) -> (i32) {
%1 = arith.addi %arg1, %c1_i32 : i32
memref.store %1, %alloca[%arg0] : memref<16xi32>
affine.yield %1 : i32
}
return
}
```
The generated `result.mlir`:
```
func.func @test_for() {
%c1_i32 = arith.constant 1 : i32
%alloca = memref.alloca() : memref<16xi32>
affine.for %arg0 = 0 to 16 step 64 iter_args(%arg1 = %c1_i32) -> () {
%0 = arith.addi %arg1, %c1_i32 : i32
memref.store %0, %alloca[%arg0] : memref<16xi32>
affine.yield
}
return
}
```
Run `mlir-opt --verify-diagnostics result.mlir`, the error is
```
result_1.mlir:4:5: error: unexpected error: custom op 'affine.for' mismatch between the number of loop-carried values and results
affine.for %arg0 = 0 to 16 step 64 iter_args(%arg1 = %c1_i32) -> () {
^
```
This issue happens when an `affine.for` only executes once. Since the loop-carried arguments (`iter_args`) will not be updated, remove-dead-values pass will remove the return values of `affine.yield`. However, `iter_args` are still left in the for loop, which leads to an invalid mlir.
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