Moving to a proper build crate `bindgen_cuda`. (#1531)

* Moving to a proper build crate `bindgen_cuda`.

* Fmt.

2 files changed, 36 insertions, 241 deletions

diff --git a/candle-flash-attn/Cargo.toml b/candle-flash-attn/Cargo.toml
index 0d3af91d..d8e8da82 100644
--- a/candle-flash-attn/Cargo.toml
+++ b/candle-flash-attn/Cargo.toml
@@ -15,9 +15,9 @@ candle = { path = "../candle-core", features = ["cuda"], package = "candle-core"
 half = { version = "2.3.1", features = ["num-traits"] }
 
 [build-dependencies]
+bindgen_cuda = "0.1.1"
 anyhow = { version = "1", features = ["backtrace"] }
-num_cpus = "1.15.0"
-rayon = "1.7.0"
+
 
 [dev-dependencies]
 anyhow = { version = "1", features = ["backtrace"] }
diff --git a/candle-flash-attn/build.rs b/candle-flash-attn/build.rs
index fde3aeed..4002770b 100644
--- a/candle-flash-attn/build.rs
+++ b/candle-flash-attn/build.rs
@@ -2,44 +2,32 @@
 // The cuda build time is very long so one can set the CANDLE_FLASH_ATTN_BUILD_DIR environment
 // variable in order to cache the compiled artifacts and avoid recompiling too often.
 use anyhow::{Context, Result};
-use rayon::prelude::*;
 use std::path::PathBuf;
-use std::str::FromStr;
 
 const KERNEL_FILES: [&str; 17] = [
-    "flash_api.cu",
-    "flash_fwd_hdim128_fp16_sm80.cu",
-    "flash_fwd_hdim160_fp16_sm80.cu",
-    "flash_fwd_hdim192_fp16_sm80.cu",
-    "flash_fwd_hdim224_fp16_sm80.cu",
-    "flash_fwd_hdim256_fp16_sm80.cu",
-    "flash_fwd_hdim32_fp16_sm80.cu",
-    "flash_fwd_hdim64_fp16_sm80.cu",
-    "flash_fwd_hdim96_fp16_sm80.cu",
-    "flash_fwd_hdim128_bf16_sm80.cu",
-    "flash_fwd_hdim160_bf16_sm80.cu",
-    "flash_fwd_hdim192_bf16_sm80.cu",
-    "flash_fwd_hdim224_bf16_sm80.cu",
-    "flash_fwd_hdim256_bf16_sm80.cu",
-    "flash_fwd_hdim32_bf16_sm80.cu",
-    "flash_fwd_hdim64_bf16_sm80.cu",
-    "flash_fwd_hdim96_bf16_sm80.cu",
+    "kernels/flash_api.cu",
+    "kernels/flash_fwd_hdim128_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim160_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim192_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim224_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim256_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim32_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim64_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim96_fp16_sm80.cu",
+    "kernels/flash_fwd_hdim128_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim160_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim192_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim224_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim256_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim32_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim64_bf16_sm80.cu",
+    "kernels/flash_fwd_hdim96_bf16_sm80.cu",
 ];
 
 fn main() -> Result<()> {
-    let num_cpus = std::env::var("RAYON_NUM_THREADS").map_or_else(
-        |_| num_cpus::get_physical(),
-        |s| usize::from_str(&s).unwrap(),
-    );
-
-    rayon::ThreadPoolBuilder::new()
-        .num_threads(num_cpus)
-        .build_global()
-        .unwrap();
-
     println!("cargo:rerun-if-changed=build.rs");
     for kernel_file in KERNEL_FILES.iter() {
-        println!("cargo:rerun-if-changed=kernels/{kernel_file}");
+        println!("cargo:rerun-if-changed={kernel_file}");
     }
     println!("cargo:rerun-if-changed=kernels/flash_fwd_kernel.h");
     println!("cargo:rerun-if-changed=kernels/flash_fwd_launch_template.h");
@@ -66,223 +54,30 @@ fn main() -> Result<()> {
             ))
         }
     };
-    set_cuda_include_dir()?;
-
-    let ccbin_env = std::env::var("CANDLE_NVCC_CCBIN");
-    println!("cargo:rerun-if-env-changed=CANDLE_NVCC_CCBIN");
 
-    let compute_cap = compute_cap()?;
+    let kernels = KERNEL_FILES.iter().collect();
+    let builder = bindgen_cuda::Builder::default()
+        .kernel_paths(kernels)
+        .out_dir(build_dir.clone())
+        .arg("-std=c++17")
+        .arg("-O3")
+        .arg("-U__CUDA_NO_HALF_OPERATORS__")
+        .arg("-U__CUDA_NO_HALF_CONVERSIONS__")
+        .arg("-U__CUDA_NO_HALF2_OPERATORS__")
+        .arg("-U__CUDA_NO_BFLOAT16_CONVERSIONS__")
+        .arg("-Icutlass/include")
+        .arg("--expt-relaxed-constexpr")
+        .arg("--expt-extended-lambda")
+        .arg("--use_fast_math")
+        .arg("--verbose");
 
     let out_file = build_dir.join("libflashattention.a");
+    builder.build_lib(out_file);
 
-    let kernel_dir = PathBuf::from("kernels");
-    let cu_files: Vec<_> = KERNEL_FILES
-        .iter()
-        .map(|f| {
-            let mut obj_file = out_dir.join(f);
-            obj_file.set_extension("o");
-            (kernel_dir.join(f), obj_file)
-        })
-        .collect();
-    let out_modified: Result<_, _> = out_file.metadata().and_then(|m| m.modified());
-    let should_compile = if out_file.exists() {
-        kernel_dir
-            .read_dir()
-            .expect("kernels folder should exist")
-            .any(|entry| {
-                if let (Ok(entry), Ok(out_modified)) = (entry, &out_modified) {
-                    let in_modified = entry.metadata().unwrap().modified().unwrap();
-                    in_modified.duration_since(*out_modified).is_ok()
-                } else {
-                    true
-                }
-            })
-    } else {
-        true
-    };
-    if should_compile {
-        cu_files
-            .par_iter()
-            .map(|(cu_file, obj_file)| {
-                let mut command = std::process::Command::new("nvcc");
-                command
-                    .arg("-std=c++17")
-                    .arg("-O3")
-                    .arg("-U__CUDA_NO_HALF_OPERATORS__")
-                    .arg("-U__CUDA_NO_HALF_CONVERSIONS__")
-                    .arg("-U__CUDA_NO_HALF2_OPERATORS__")
-                    .arg("-U__CUDA_NO_BFLOAT16_CONVERSIONS__")
-                    .arg(format!("--gpu-architecture=sm_{compute_cap}"))
-                    .arg("-c")
-                    .args(["-o", obj_file.to_str().unwrap()])
-                    .args(["--default-stream", "per-thread"])
-                    .arg("-Icutlass/include")
-                    .arg("--expt-relaxed-constexpr")
-                    .arg("--expt-extended-lambda")
-                    .arg("--use_fast_math")
-                    .arg("--verbose");
-                if let Ok(ccbin_path) = &ccbin_env {
-                    command
-                        .arg("-allow-unsupported-compiler")
-                        .args(["-ccbin", ccbin_path]);
-                }
-                command.arg(cu_file);
-                let output = command
-                    .spawn()
-                    .context("failed spawning nvcc")?
-                    .wait_with_output()?;
-                if !output.status.success() {
-                    anyhow::bail!(
-                        "nvcc error while executing compiling: {:?}\n\n# stdout\n{:#}\n\n# stderr\n{:#}",
-                        &command,
-                        String::from_utf8_lossy(&output.stdout),
-                        String::from_utf8_lossy(&output.stderr)
-                    )
-                }
-                Ok(())
-            })
-            .collect::<Result<()>>()?;
-        let obj_files = cu_files.iter().map(|c| c.1.clone()).collect::<Vec<_>>();
-        let mut command = std::process::Command::new("nvcc");
-        command
-            .arg("--lib")
-            .args(["-o", out_file.to_str().unwrap()])
-            .args(obj_files);
-        let output = command
-            .spawn()
-            .context("failed spawning nvcc")?
-            .wait_with_output()?;
-        if !output.status.success() {
-            anyhow::bail!(
-                "nvcc error while linking: {:?}\n\n# stdout\n{:#}\n\n# stderr\n{:#}",
-                &command,
-                String::from_utf8_lossy(&output.stdout),
-                String::from_utf8_lossy(&output.stderr)
-            )
-        }
-    }
     println!("cargo:rustc-link-search={}", build_dir.display());
     println!("cargo:rustc-link-lib=flashattention");
     println!("cargo:rustc-link-lib=dylib=cudart");
     println!("cargo:rustc-link-lib=dylib=stdc++");
 
-    /* laurent: I tried using the cc cuda integration as below but this lead to ptaxs never
-       finishing to run for some reason. Calling nvcc manually worked fine.
-    cc::Build::new()
-        .cuda(true)
-        .include("cutlass/include")
-        .flag("--expt-relaxed-constexpr")
-        .flag("--default-stream")
-        .flag("per-thread")
-        .flag(&format!("--gpu-architecture=sm_{compute_cap}"))
-        .file("kernels/flash_fwd_hdim32_fp16_sm80.cu")
-        .compile("flashattn");
-    */
     Ok(())
 }
-
-fn set_cuda_include_dir() -> Result<()> {
-    // NOTE: copied from cudarc build.rs.
-    let env_vars = [
-        "CUDA_PATH",
-        "CUDA_ROOT",
-        "CUDA_TOOLKIT_ROOT_DIR",
-        "CUDNN_LIB",
-    ];
-    let env_vars = env_vars
-        .into_iter()
-        .map(std::env::var)
-        .filter_map(Result::ok)
-        .map(Into::<PathBuf>::into);
-
-    let roots = [
-        "/usr",
-        "/usr/local/cuda",
-        "/opt/cuda",
-        "/usr/lib/cuda",
-        "C:/Program Files/NVIDIA GPU Computing Toolkit",
-        "C:/CUDA",
-    ];
-    let roots = roots.into_iter().map(Into::<PathBuf>::into);
-    let root = env_vars
-        .chain(roots)
-        .find(|path| path.join("include").join("cuda.h").is_file())
-        .context("cannot find include/cuda.h")?;
-    println!(
-        "cargo:rustc-env=CUDA_INCLUDE_DIR={}",
-        root.join("include").display()
-    );
-    Ok(())
-}
-
-#[allow(unused)]
-fn compute_cap() -> Result<usize> {
-    println!("cargo:rerun-if-env-changed=CUDA_COMPUTE_CAP");
-
-    // Try to parse compute caps from env
-    let mut compute_cap = if let Ok(compute_cap_str) = std::env::var("CUDA_COMPUTE_CAP") {
-        println!("cargo:rustc-env=CUDA_COMPUTE_CAP={compute_cap_str}");
-        compute_cap_str
-            .parse::<usize>()
-            .context("Could not parse compute cap")?
-    } else {
-        // Use nvidia-smi to get the current compute cap
-        let out = std::process::Command::new("nvidia-smi")
-            .arg("--query-gpu=compute_cap")
-            .arg("--format=csv")
-            .output()
-            .context("`nvidia-smi` failed. Ensure that you have CUDA installed and that `nvidia-smi` is in your PATH.")?;
-        let out = std::str::from_utf8(&out.stdout).context("stdout is not a utf8 string")?;
-        let mut lines = out.lines();
-        assert_eq!(
-            lines.next().context("missing line in stdout")?,
-            "compute_cap"
-        );
-        let cap = lines
-            .next()
-            .context("missing line in stdout")?
-            .replace('.', "");
-        let cap = cap
-            .parse::<usize>()
-            .with_context(|| format!("cannot parse as int {cap}"))?;
-        println!("cargo:rustc-env=CUDA_COMPUTE_CAP={cap}");
-        cap
-    };
-
-    // Grab available GPU codes from nvcc and select the highest one
-    let (supported_nvcc_codes, max_nvcc_code) = {
-        let out = std::process::Command::new("nvcc")
-            .arg("--list-gpu-code")
-            .output()
-            .expect("`nvcc` failed. Ensure that you have CUDA installed and that `nvcc` is in your PATH.");
-        let out = std::str::from_utf8(&out.stdout).unwrap();
-
-        let out = out.lines().collect::<Vec<&str>>();
-        let mut codes = Vec::with_capacity(out.len());
-        for code in out {
-            let code = code.split('_').collect::<Vec<&str>>();
-            if !code.is_empty() && code.contains(&"sm") {
-                if let Ok(num) = code[1].parse::<usize>() {
-                    codes.push(num);
-                }
-            }
-        }
-        codes.sort();
-        let max_nvcc_code = *codes.last().context("no gpu codes parsed from nvcc")?;
-        (codes, max_nvcc_code)
-    };
-
-    // Check that nvcc supports the asked compute caps
-    if !supported_nvcc_codes.contains(&compute_cap) {
-        anyhow::bail!(
-            "nvcc cannot target gpu arch {compute_cap}. Available nvcc targets are {supported_nvcc_codes:?}."
-        );
-    }
-    if compute_cap > max_nvcc_code {
-        anyhow::bail!(
-            "CUDA compute cap {compute_cap} is higher than the highest gpu code from nvcc {max_nvcc_code}"
-        );
-    }
-
-    Ok(compute_cap)
-}