Fix offset calculation in kernel launch

1 files changed, 10 insertions, 8 deletions

diff --git a/zluda/src/impl/function.rs b/zluda/src/impl/function.rs
index 4f2006c..638d08a 100644
--- a/zluda/src/impl/function.rs
+++ b/zluda/src/impl/function.rs
@@ -110,23 +110,24 @@ pub fn launch_kernel(
             match (buffer_size, buffer_ptr) {
                 (Some(buffer_size), Some(buffer_ptr)) => {
                     let sum_of_kernel_argument_sizes =
-                        func.arg_size.iter().fold(0, |offset, size_of_arg| {
-                            size_of_arg + round_up_to_multiple(offset, *size_of_arg)
-                        });
+                        func.arg_size
+                            .iter()
+                            .fold(0, |sum_of_arg_sizes, size_of_arg| {
+                                sum_of_arg_sizes + align_to_usize(*size_of_arg)
+                            });
                     if buffer_size != sum_of_kernel_argument_sizes {
                         return Err(CUresult::CUDA_ERROR_INVALID_VALUE);
                     }
                     let mut offset = 0;
                     for (i, arg_size) in func.arg_size.iter().enumerate() {
-                        let buffer_offset = round_up_to_multiple(offset, *arg_size);
                         unsafe {
                             func.base.set_arg_raw(
                                 i as u32,
                                 *arg_size,
-                                buffer_ptr.add(buffer_offset) as *const _,
+                                buffer_ptr.add(offset) as *const _,
                             )?
                         };
-                        offset = buffer_offset + *arg_size;
+                        offset += align_to_usize(*arg_size);
                     }
                 }
                 _ => return Err(CUresult::CUDA_ERROR_INVALID_VALUE),
@@ -159,8 +160,9 @@ pub fn launch_kernel(
     })?
 }
 
-fn round_up_to_multiple(x: usize, multiple: usize) -> usize {
-    ((x + multiple - 1) / multiple) * multiple
+fn align_to_usize(value: usize) -> usize {
+    let multiple = std::mem::size_of::<usize>();
+    ((value + multiple - 1) / multiple) * multiple
 }
 
 pub(crate) fn get_attribute(