pstarkcdpr

Implement missing stablehlo.fft operations

6

See issue [#22695](https://github.com/iree-org/iree/issues/22695). This change does the following: - Causes a compile error when the fft length has more than 1 dimension (this was never supported but previously gave the...

Getting "op exceeded stack allocation limit" from linalg_ext.fft

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### What happened? The `linalg_ext.fft` operation outputs 2 tensors: the real part and the imaginary part of the operation. If the tensors are large enough and one of the output...

Getting "One or more operations with large vector sizes were found" error from linalg_ext.fft

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### What happened? [rfft_repro.zip](https://github.com/user-attachments/files/23226191/rfft_repro.zip) I have a simple repro case where `linalg_ext.fft` causes the following compile error: ``` rfft_repro.mlir:25:12: error: One or more operations with large vector sizes (32768 bytes)...

Improvements to stablehlo.fft

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### Request description Currently, lowering `stablehlo.fft` has a number of issues, including: 1. Only `RFFT` is supported by the compiler, even though `FFT`, `IFFT`, and `IRFFT` are accepted by StableHLO....