[flang-commits] [flang] [flang][cuda] Correct the number of blocks when setting the grid to `*` (PR #121000)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-runtime

Author: None (khaki3)

<details>
<summary>Changes</summary>

We set the `gridX` argument of `_FortranACUFLaunchKernel` to `-1` when `*` is passed to the grid parameter. We store it in one of `dim3` members. However, `dim3` members are unsigned, so positive-value checks we use later, such as `gridDim.x > 0`, are invalid. This PR utilizes the original gird-size arguments to compute the number of blocks.

---
Full diff: https://github.com/llvm/llvm-project/pull/121000.diff


1 Files Affected:

- (modified) flang/runtime/CUDA/kernel.cpp (+6-6) 


``````````diff
diff --git a/flang/runtime/CUDA/kernel.cpp b/flang/runtime/CUDA/kernel.cpp
index 88cdf3cf426229..bdc04ccb17672b 100644
--- a/flang/runtime/CUDA/kernel.cpp
+++ b/flang/runtime/CUDA/kernel.cpp
@@ -48,13 +48,13 @@ void RTDEF(CUFLaunchKernel)(const void *kernel, intptr_t gridX, intptr_t gridY,
       maxBlocks = multiProcCount * maxBlocks;
     }
     if (maxBlocks > 0) {
-      if (gridDim.x > 0) {
+      if (gridX > 0) {
         maxBlocks = maxBlocks / gridDim.x;
       }
-      if (gridDim.y > 0) {
+      if (gridY > 0) {
         maxBlocks = maxBlocks / gridDim.y;
       }
-      if (gridDim.z > 0) {
+      if (gridZ > 0) {
         maxBlocks = maxBlocks / gridDim.z;
       }
       if (maxBlocks < 1) {
@@ -113,13 +113,13 @@ void RTDEF(CUFLaunchClusterKernel)(const void *kernel, intptr_t clusterX,
       maxBlocks = multiProcCount * maxBlocks;
     }
     if (maxBlocks > 0) {
-      if (config.gridDim.x > 0) {
+      if (gridX > 0) {
         maxBlocks = maxBlocks / config.gridDim.x;
       }
-      if (config.gridDim.y > 0) {
+      if (gridY > 0) {
         maxBlocks = maxBlocks / config.gridDim.y;
       }
-      if (config.gridDim.z > 0) {
+      if (gridZ > 0) {
         maxBlocks = maxBlocks / config.gridDim.z;
       }
       if (maxBlocks < 1) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/121000