NVPTX syscalls

Author: denzp

crates/core_arch/src/nvptx/mod.rs

@@ -11,6 +11,8 @@
 //! [llvm_docs]:
 //! https://llvm.org/docs/NVPTXUsage.html
 
+use core::ffi::c_void;
+
 #[allow(improper_ctypes)]
 extern "C" {
     #[link_name = "llvm.nvvm.barrier0"]
@@ -124,3 +126,88 @@ pub unsafe fn _thread_idx_z() -> i32 {
 pub unsafe fn trap() -> ! {
     crate::intrinsics::abort()
 }
+
+// Basic CUDA syscall declarations.
+extern "C" {
+    /// Print formatted output from a kernel to a host-side output stream.
+    ///
+    /// Syscall arguments:
+    /// * `status`: The status value that is returned by `vprintf`.
+    /// * `format`: A pointer to the format specifier input (uses common `printf` format).
+    /// * `valist`: A pointer to the valist input.
+    ///
+    /// ```
+    /// #[repr(C)]
+    /// struct PrintArgs(f32, f32, f32, i32);
+    ///
+    /// vprintf(
+    ///     "int(%f + %f) = int(%f) = %d\n".as_ptr(),
+    ///     transmute(&PrintArgs(a, b, a + b, (a + b) as i32)),
+    /// );
+    /// ```
+    ///
+    /// Sources:
+    /// [Programming Guide](https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#formatted-output),
+    /// [PTX Interoperability](https://docs.nvidia.com/cuda/ptx-writers-guide-to-interoperability/index.html#system-calls).
+    pub fn vprintf(format: *const u8, valist: *const c_void) -> i32;
+
+    /// Allocate memory dynamically from a fixed-size heap in global memory.
+    ///
+    /// The CUDA in-kernel `malloc()` function allocates at least `size` bytes
+    /// from the device heap and returns a pointer to the allocated memory
+    /// or `NULL` if insufficient memory exists to fulfill the request.
+    ///
+    /// The returned pointer is guaranteed to be aligned to a 16-byte boundary.
+    ///
+    /// The memory allocated by a given CUDA thread via `malloc()` remains allocated
+    /// for the lifetime of the CUDA context, or until it is explicitly released
+    /// by a call to `free()`. It can be used by any other CUDA threads
+    /// even from subsequent kernel launches.
+    ///
+    /// Sources:
+    /// [Programming Guide](https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#dynamic-global-memory-allocation-and-operations),
+    /// [PTX Interoperability](https://docs.nvidia.com/cuda/ptx-writers-guide-to-interoperability/index.html#system-calls).
+    // FIXME(denzp): assign `malloc` and `nothrow` attributes.
+    pub fn malloc(size: usize) -> *mut c_void;
+
+    /// Free previously dynamically allocated memory.
+    ///
+    /// The CUDA in-kernel `free()` function deallocates the memory pointed to by `ptr`,
+    /// which must have been returned by a previous call to `malloc()`. If `ptr` is NULL,
+    /// the call to `free()` is ignored.
+    ///
+    /// Any CUDA thread may free memory allocated by another thread, but care should be taken
+    /// to ensure that the same pointer is not freed more than once. Repeated calls to `free()`
+    /// with the same `ptr` has undefined behavior.
+    ///
+    /// Sources:
+    /// [Programming Guide](https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#dynamic-global-memory-allocation-and-operations),
+    /// [PTX Interoperability](https://docs.nvidia.com/cuda/ptx-writers-guide-to-interoperability/index.html#system-calls).
+    // FIXME(denzp): assign `nothrow` attribute.
+    pub fn free(ptr: *mut c_void);
+
+    // Internal declaration of the syscall. Exported variant has
+    // the `char_size` parameter set to `1` (single char size in bytes).
+    fn __assertfail(
+        message: *const u8,
+        file: *const u8,
+        line: u32,
+        function: *const u8,
+        char_size: usize,
+    );
+}
+
+/// Syscall to be used whenever the *assert expression produces a `false` value*.
+///
+/// Syscall arguments:
+/// * `message`: The pointer to the string that should be output.
+/// * `file`: The pointer to the file name string associated with the assert.
+/// * `line`: The line number associated with the assert.
+/// * `function`: The pointer to the function name string associated with the assert.
+///
+/// Source:
+/// [PTX Interoperability](https://docs.nvidia.com/cuda/ptx-writers-guide-to-interoperability/index.html#system-calls).
+#[inline]
+pub unsafe fn __assert_fail(message: *const u8, file: *const u8, line: u32, function: *const u8) {
+    __assertfail(message, file, line, function, 1)
+}