Backend refactoring. (#1966)

* Backend refactoring.

* Metal tweaks.

* Move the cudnn module.

candle-core/src/cuda_backend/cudnn.rs

@@ -0,0 +1,123 @@
+use crate::WithDType;
+use cudarc;
+use cudarc::cudnn::safe::{Conv2dForward, Cudnn};
+use cudarc::driver::{CudaSlice, CudaView, DeviceRepr, ValidAsZeroBits};
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::sync::Arc;
+
+// The cudnn handles are stored per thread here rather than on the CudaDevice as they are neither
+// send nor sync.
+thread_local! {
+    static CUDNN: RefCell<HashMap<crate::cuda_backend::DeviceId, Arc<Cudnn>>> = HashMap::new().into();
+}
+
+impl From<cudarc::cudnn::CudnnError> for crate::Error {
+    fn from(err: cudarc::cudnn::CudnnError) -> Self {
+        crate::Error::wrap(err)
+    }
+}
+
+impl From<cudarc::driver::DriverError> for crate::Error {
+    fn from(err: cudarc::driver::DriverError) -> Self {
+        crate::Error::wrap(err)
+    }
+}
+
+pub(crate) fn launch_conv2d<
+    T: DeviceRepr + WithDType + ValidAsZeroBits + cudarc::cudnn::CudnnDataType,
+>(
+    src: &CudaView<T>,
+    src_l: &crate::Layout,
+    filter: &CudaView<T>,
+    dst: &mut CudaSlice<T>,
+    params: &crate::conv::ParamsConv2D,
+    dev: &crate::cuda_backend::CudaDevice,
+) -> crate::Result<()> {
+    use crate::conv::CudnnFwdAlgo as CandleAlgo;
+    use cudarc::cudnn::sys::cudnnConvolutionFwdAlgo_t as A;
+
+    let device_id = dev.id();
+    let cudnn = CUDNN.with(|cudnn| {
+        if let Some(cudnn) = cudnn.borrow().get(&device_id) {
+            return Ok(cudnn.clone());
+        }
+        let c = Cudnn::new(dev.cuda_device());
+        if let Ok(c) = &c {
+            cudnn.borrow_mut().insert(device_id, c.clone());
+        }
+        c
+    })?;
+    let conv = cudnn.create_conv2d::<T>(
+        /* pad */ [params.padding as i32, params.padding as i32],
+        /* stride */ [params.stride as i32, params.stride as i32],
+        /* dilation */ [params.dilation as i32, params.dilation as i32],
+        cudarc::cudnn::sys::cudnnConvolutionMode_t::CUDNN_CROSS_CORRELATION,
+    )?;
+    let x_shape = [
+        params.b_size as i32,
+        params.c_in as i32,
+        params.i_h as i32,
+        params.i_w as i32,
+    ];
+    // Note that `src` already starts at the proper offset.
+    let x = if src_l.is_contiguous() {
+        cudnn.create_4d_tensor(
+            cudarc::cudnn::sys::cudnnTensorFormat_t::CUDNN_TENSOR_NCHW,
+            x_shape,
+        )?
+    } else {
+        let s = src_l.stride();
+        cudnn.create_4d_tensor_ex(
+            x_shape,
+            [s[0] as i32, s[1] as i32, s[2] as i32, s[3] as i32],
+        )?
+    };
+    let w = cudnn.create_4d_filter(
+        cudarc::cudnn::sys::cudnnTensorFormat_t::CUDNN_TENSOR_NCHW,
+        [
+            params.c_out as i32,
+            params.c_in as i32,
+            params.k_h as i32,
+            params.k_w as i32,
+        ],
+    )?;
+    let (w_out, h_out) = (params.out_w() as i32, params.out_h() as i32);
+    let y = cudnn.create_4d_tensor(
+        cudarc::cudnn::sys::cudnnTensorFormat_t::CUDNN_TENSOR_NCHW,
+        [params.b_size as i32, params.c_out as i32, h_out, w_out],
+    )?;
+    let conv2d = Conv2dForward {
+        conv: &conv,
+        x: &x,
+        w: &w,
+        y: &y,
+    };
+    let alg = match params.cudnn_fwd_algo {
+        None => conv2d.pick_algorithm()?,
+        Some(CandleAlgo::ImplicitGemm) => A::CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_GEMM,
+        Some(CandleAlgo::ImplicitPrecompGemm) => {
+            A::CUDNN_CONVOLUTION_FWD_ALGO_IMPLICIT_PRECOMP_GEMM
+        }
+        Some(CandleAlgo::Gemm) => A::CUDNN_CONVOLUTION_FWD_ALGO_GEMM,
+        Some(CandleAlgo::Direct) => A::CUDNN_CONVOLUTION_FWD_ALGO_DIRECT,
+        Some(CandleAlgo::Fft) => A::CUDNN_CONVOLUTION_FWD_ALGO_FFT,
+        Some(CandleAlgo::FftTiling) => A::CUDNN_CONVOLUTION_FWD_ALGO_FFT_TILING,
+        Some(CandleAlgo::Winograd) => A::CUDNN_CONVOLUTION_FWD_ALGO_WINOGRAD,
+        Some(CandleAlgo::WinogradNonFused) => A::CUDNN_CONVOLUTION_FWD_ALGO_WINOGRAD_NONFUSED,
+        Some(CandleAlgo::Count) => A::CUDNN_CONVOLUTION_FWD_ALGO_COUNT,
+    };
+    let workspace_size = conv2d.get_workspace_size(alg)?;
+    let mut workspace = dev.cuda_device().alloc_zeros::<u8>(workspace_size)?;
+    unsafe {
+        conv2d.launch::<CudaSlice<u8>, _, _, _>(
+            alg,
+            Some(&mut workspace),
+            (T::one(), T::zero()),
+            src,
+            filter,
+            dst,
+        )?;
+    }
+    Ok(())
+}