HIP: fix ordering in 2d plan

AMReX-Codes · Nov 8, 2024 · cc2b616 · cc2b616
1 parent 5749b03
commit cc2b616
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/Src/FFT/AMReX_FFT_Helper.H b/Src/FFT/AMReX_FFT_Helper.H
@@ -188,9 +188,10 @@ struct Plan
         int len[2] = {};
         if (rank == 1) {
             len[0] = box.length(0);
+            len[1] = box.length(0); // Not used except for HIP. Yes it's `(0)`.
         } else {
-            len[0] = box.length(1);
-            len[1] = box.length(0);
+            len[0] = box.length(1); // Most FFT libraries assume row-major ordering
+            len[1] = box.length(0); // except for rocfft
         }
         int nr = (rank == 1) ? len[0] : len[0]*len[1];
         n = nr;
@@ -221,7 +222,8 @@ struct Plan
 #elif defined(AMREX_USE_HIP)
 
         auto prec = std::is_same_v<float,T> ? rocfft_precision_single : rocfft_precision_double;
-        const std::size_t length[2] = {std::size_t(len[0]), std::size_t(len[1])};
+	// switch to column-major ordering
+        std::size_t length[2] = {std::size_t(len[1]), std::size_t(len[0])};
         if constexpr (D == Direction::forward) {
             AMREX_ROCFFT_SAFE_CALL
                 (rocfft_plan_create(&plan, rocfft_placement_notinplace,