Files
xtrain/crates/xtrain-cuda/build.rs
Gahow Wang 7fb1a29057 ops: embedding/reshape/transpose/split-merge-heads fwd+bwd
Phase T5 structural ops on top of the T4 set, needed to assemble the
tiny transformer:
- embedding: gather rows by I32 ids (CUDA kernel) / scatter-add backward
  (atomic, so repeated ids accumulate). csrc/ops/model.cu + ffi.
- reshape: contiguous metadata-only view (Tensor::reshape), no kernel.
- transpose_3d01: [a,b,c]->[b,a,c] for the multi-head layout (kernel).
- autograd nodes: embedding/reshape/transpose_3d01/transpose_2d, plus
  split_heads (->Vec<Var>) / merge_heads for per-head attention.
- tape: Var::zero_grad + set_value so a hand-written GD step can update
  params and clear grads between steps.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-15 16:05:09 +08:00

46 lines
1.6 KiB
Rust

use std::env;
use std::path::Path;
use std::process::Command;
fn main() {
println!("cargo:rustc-check-cfg=cfg(no_cuda)");
println!("cargo:rerun-if-changed=../../csrc/");
let cuda_path = env::var("CUDA_HOME")
.or_else(|_| env::var("CUDA_PATH"))
.unwrap_or_else(|_| "/usr/local/cuda".to_string());
// Locally there is no nvcc / GPU. Detect that and skip the CUDA build so
// `cargo check`/`cargo build` of host-side Rust still works. The `no_cuda`
// cfg makes the FFI bindings + smoke test compile (but not run) without nvcc.
if !nvcc_available(&cuda_path) {
println!("cargo:warning=nvcc not found — skipping CUDA compilation (host-only build).");
println!("cargo:rustc-cfg=no_cuda");
return;
}
println!("cargo:rustc-link-search=native={cuda_path}/lib64");
println!("cargo:rustc-link-lib=dylib=cudart");
println!("cargo:rustc-link-lib=dylib=cuda");
// cuBLAS is used only as a correctness reference for the hand-written GEMM.
println!("cargo:rustc-link-lib=dylib=cublas");
cc::Build::new()
.cuda(true)
.cudart("shared")
.flag("-gencode=arch=compute_120,code=sm_120")
.file("../../csrc/test/vecadd.cu")
.file("../../csrc/ops/elementwise.cu")
.file("../../csrc/ops/gemm.cu")
.file("../../csrc/ops/nn.cu")
.file("../../csrc/ops/model.cu")
.compile("xtrain_cuda_kernels");
}
fn nvcc_available(cuda_path: &str) -> bool {
if Command::new("nvcc").arg("--version").output().is_ok() {
return true;
}
Path::new(&format!("{cuda_path}/bin/nvcc")).exists()
}