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The FFT app doesn't actually work for 1D ffts #9449

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Merged
mcourteaux merged 1 commit into from
Sep 15, 2026
+5 −6
Merged

The FFT app doesn't actually work for 1D ffts #9449

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1 change: 1 addition & 0 deletions apps/fft/fft.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1064,6 +1064,7 @@ namespace {

// Compute a factorization of N suitable for use in the FFT.
vector<int> radix_factor(int N) {
assert(N > 0);
// Some special cases to optimize.
switch (N) {
case 16:
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10 changes: 4 additions & 6 deletions apps/fft/fft_generator.cpp
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Expand Up @@ -63,11 +63,9 @@ class FFTGenerator : public Halide::Generator<FFTGenerator> {
GeneratorParam<FFTNumberType> output_number_type{"output_number_type",
FFTNumberType::Real, fft_number_type_enum_map()};

// Size of first dimension, required to be greater than zero.
GeneratorParam<int32_t> size0{"size0", 1};
// Size of second dimension, may be zero for 1D FFT.
GeneratorParam<int32_t> size1{"size1", 0};
// TODO(zalman): Add support for 3D and maybe 4D FFTs
// Size of dimensions, required to be greater than one
GeneratorParam<int32_t> size0{"size0", 2};
GeneratorParam<int32_t> size1{"size1", 2};

// The input buffer. Must be separate from the output.
// Only Float(32) is supported.
Expand All @@ -85,7 +83,7 @@ class FFTGenerator : public Halide::Generator<FFTGenerator> {
Output<Buffer<float, 3>> output{"output"};

void generate() {
_halide_user_assert(size0 > 0) << "FFT must be at least 1D\n";
_halide_user_assert(size0 > 1 && size1 > 1) << "Both dimensions must be at least size 2\n";

Fft2dDesc desc;

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