[flang-commits] [flang] e9866d5 - [flang][cuda] Fix GPULaunchKernelConversion to generate correct kernel launch parameters (#119431)

[via flang-commits]

Author: khaki3
Date: 2024-12-10T11:32:32-08:00
New Revision: e9866d5d149706eac26f45bf0cab933c51d6d1cd

URL: https://github.com/llvm/llvm-project/commit/e9866d5d149706eac26f45bf0cab933c51d6d1cd
DIFF: https://github.com/llvm/llvm-project/commit/e9866d5d149706eac26f45bf0cab933c51d6d1cd.diff

LOG: [flang][cuda] Fix GPULaunchKernelConversion to generate correct kernel launch parameters (#119431)

For the call to _FortranACUFLaunchKernel, we store the pointer to a
member of a temporary structure in a parameter array. However, when we
obtain an element pointer from the parameter array, its address is
calculated based on the type of the structure. This PR properly treats
the parameter array as an array of pointers.

Example:

```mlir
%30 = llvm.load %29 : !llvm.ptr -> i32
%31 = llvm.mlir.constant(1 : i32) : i32
%32 = llvm.alloca %31 x !llvm.struct<(i64, i64, i32, ptr)> : (i32) -> !llvm.ptr
%33 = llvm.mlir.constant(4 : i32) : i32
%34 = llvm.alloca %33 x !llvm.ptr : (i32) -> !llvm.ptr
%35 = llvm.mlir.constant(0 : i32) : i32
%36 = llvm.getelementptr %32[%35] : (!llvm.ptr, i32) -> !llvm.ptr, !llvm.struct<(i64, i64, i32, ptr)>
llvm.store %8, %36 : i64, !llvm.ptr
%37 = llvm.getelementptr %34[%35] : (!llvm.ptr, i32) -> !llvm.ptr, !llvm.struct<(i64, i64, i32, ptr)>
llvm.store %36, %37 : !llvm.ptr, !llvm.ptr
...
llvm.call @_FortranACUFLaunchKernel(%47, %8, %8, %8, %2, %8, %8, %7, %34, %48) : (!llvm.ptr, i64, i64, i64, i64, i64, i64, i32, !llvm.ptr, !llvm.ptr) -> () 
```
In this example, `%37 = llvm.getelementptr %34[%35] : (!llvm.ptr, i32)
-> !llvm.ptr, !llvm.struct<(i64, i64, i32, ptr)>` will be `%37 =
llvm.getelementptr %34[%35] : (!llvm.ptr, i32) -> !llvm.ptr, !llvm.ptr`.

Added: 
    

Modified: 
    flang/lib/Optimizer/Transforms/CUFGPUToLLVMConversion.cpp
    flang/test/Fir/CUDA/cuda-gpu-launch-func.mlir

Removed: 
    


################################################################################
diff  --git a/flang/lib/Optimizer/Transforms/CUFGPUToLLVMConversion.cpp b/flang/lib/Optimizer/Transforms/CUFGPUToLLVMConversion.cpp
index c64f35542a6e59..426cd52b7ef83e 100644
--- a/flang/lib/Optimizer/Transforms/CUFGPUToLLVMConversion.cpp
+++ b/flang/lib/Optimizer/Transforms/CUFGPUToLLVMConversion.cpp
@@ -58,7 +58,7 @@ static mlir::Value createKernelArgArray(mlir::Location loc,
         loc, ptrTy, structTy, argStruct, mlir::ArrayRef<mlir::Value>({indice}));
     rewriter.create<LLVM::StoreOp>(loc, arg, structMember);
     mlir::Value arrayMember = rewriter.create<LLVM::GEPOp>(
-        loc, ptrTy, structTy, argArray, mlir::ArrayRef<mlir::Value>({indice}));
+        loc, ptrTy, ptrTy, argArray, mlir::ArrayRef<mlir::Value>({indice}));
     rewriter.create<LLVM::StoreOp>(loc, structMember, arrayMember);
   }
   return argArray;

diff  --git a/flang/test/Fir/CUDA/cuda-gpu-launch-func.mlir b/flang/test/Fir/CUDA/cuda-gpu-launch-func.mlir
index 7fede7c6c17b78..accdeae30aa61c 100644
--- a/flang/test/Fir/CUDA/cuda-gpu-launch-func.mlir
+++ b/flang/test/Fir/CUDA/cuda-gpu-launch-func.mlir
@@ -99,9 +99,16 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<i1, dense<8> : ve
 }
 
 // CHECK-LABEL: _QMmod1Phost_sub
-
+// CHECK: %[[STRUCT:.*]] = llvm.alloca %{{.*}} x !llvm.struct<(ptr)> : (i32) -> !llvm.ptr
+// CHECK: %[[PARAMS:.*]] = llvm.alloca %{{.*}} x !llvm.ptr : (i32) -> !llvm.ptr
+// CHECK: %[[ZERO:.*]] = llvm.mlir.constant(0 : i32) : i32
+// CHECK: %[[STRUCT_PTR:.*]] = llvm.getelementptr %[[STRUCT]][%[[ZERO]]] : (!llvm.ptr, i32) -> !llvm.ptr, !llvm.struct<(ptr)>
+// CHECK: llvm.store %{{.*}}, %[[STRUCT_PTR]] : !llvm.ptr, !llvm.ptr
+// CHECK: %[[PARAM_PTR:.*]] = llvm.getelementptr %[[PARAMS]][%[[ZERO]]] : (!llvm.ptr, i32) -> !llvm.ptr, !llvm.ptr
+// CHECK: llvm.store %[[STRUCT_PTR]], %[[PARAM_PTR]] : !llvm.ptr, !llvm.ptr
 // CHECK: %[[KERNEL_PTR:.*]] = llvm.mlir.addressof @_QMmod1Psub1 : !llvm.ptr
-// CHECK: llvm.call @_FortranACUFLaunchKernel(%[[KERNEL_PTR]], {{.*}})
+// CHECK: %[[NULL:.*]] = llvm.mlir.zero : !llvm.ptr
+// CHECK: llvm.call @_FortranACUFLaunchKernel(%[[KERNEL_PTR]], {{.*}}, %[[PARAMS]], %[[NULL]])
 
 // -----