[flang-commits] [flang] [flang][cuda] Add interface and lower barrier_init (PR #162929)

[Valentin Clement バレンタイン クレメン via flang-commits]

https://github.com/clementval created https://github.com/llvm/llvm-project/pull/162929

Add interface for `barrier_init` and lower it to the NVVM Op. 

https://github.com/clementval/llvm-project/pull/new/cuf_barrier_init

>From bc1ee80eb8abe784f42e59497202bd43ca154bb6 Mon Sep 17 00:00:00 2001
From: Valentin Clement <clementval at gmail.com>
Date: Fri, 10 Oct 2025 14:50:27 -0700
Subject: [PATCH] [flang][cuda] Add interface and lower barrier_init

---
 .../flang/Optimizer/Builder/IntrinsicCall.h   |  1 +
 flang/lib/Optimizer/Builder/IntrinsicCall.cpp | 20 +++++++++++++++++++
 flang/module/cudadevice.f90                   |  7 +++++++
 flang/test/Lower/CUDA/cuda-device-proc.cuf    | 15 ++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
index 320f913858956..695221cbcb42c 100644
--- a/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
+++ b/flang/include/flang/Optimizer/Builder/IntrinsicCall.h
@@ -208,6 +208,7 @@ struct IntrinsicLibrary {
   fir::ExtendedValue genAssociated(mlir::Type,
                                    llvm::ArrayRef<fir::ExtendedValue>);
   mlir::Value genAtand(mlir::Type, llvm::ArrayRef<mlir::Value>);
+  void genBarrierInit(llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genBesselJn(mlir::Type,
                                  llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genBesselYn(mlir::Type,
diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
index de7694ffd468c..2c21868295528 100644
--- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
@@ -346,6 +346,10 @@ static constexpr IntrinsicHandler handlers[]{
      &I::genVoteSync<mlir::NVVM::VoteSyncKind::ballot>,
      {{{"mask", asValue}, {"pred", asValue}}},
      /*isElemental=*/false},
+    {"barrier_init",
+     &I::genBarrierInit,
+     {{{"barrier", asAddr}, {"count", asValue}}},
+     /*isElemental=*/false},
     {"bessel_jn",
      &I::genBesselJn,
      {{{"n1", asValue}, {"n2", asValue}, {"x", asValue}}},
@@ -3176,6 +3180,22 @@ IntrinsicLibrary::genAssociated(mlir::Type resultType,
   return fir::runtime::genAssociated(builder, loc, pointerBox, targetBox);
 }
 
+// BARRIER_INIT (CUDA)
+void IntrinsicLibrary::genBarrierInit(llvm::ArrayRef<fir::ExtendedValue> args) {
+  assert(args.size() == 2);
+  auto llvmPtr = fir::ConvertOp::create(
+      builder, loc, mlir::LLVM::LLVMPointerType::get(builder.getContext()),
+      fir::getBase(args[0]));
+  auto addrCast = mlir::LLVM::AddrSpaceCastOp::create(
+      builder, loc,
+      mlir::LLVM::LLVMPointerType::get(
+          builder.getContext(),
+          static_cast<unsigned>(mlir::NVVM::NVVMMemorySpace::Shared)),
+      llvmPtr);
+  mlir::NVVM::MBarrierInitSharedOp::create(builder, loc, addrCast,
+                                           fir::getBase(args[1]), {});
+}
+
 // BESSEL_JN
 fir::ExtendedValue
 IntrinsicLibrary::genBesselJn(mlir::Type resultType,
diff --git a/flang/module/cudadevice.f90 b/flang/module/cudadevice.f90
index 1598c64db2cb5..4f552dcf08372 100644
--- a/flang/module/cudadevice.f90
+++ b/flang/module/cudadevice.f90
@@ -1987,6 +1987,13 @@ attributes(device,host) logical function on_device() bind(c)
     end function
   end interface
 
+  interface 
+    attributes(device) subroutine barrier_init(barrier, count)
+      integer(8) :: barrier
+      integer(4) :: count
+    end subroutine
+  end interface
+
 contains
 
   attributes(device) subroutine syncthreads()
diff --git a/flang/test/Lower/CUDA/cuda-device-proc.cuf b/flang/test/Lower/CUDA/cuda-device-proc.cuf
index 5e1f6b66d1d53..1f825436cf416 100644
--- a/flang/test/Lower/CUDA/cuda-device-proc.cuf
+++ b/flang/test/Lower/CUDA/cuda-device-proc.cuf
@@ -417,3 +417,18 @@ end subroutine
 ! CHECK-DAG: func.func private @__ldcs_r8x2_(!fir.ref<!fir.array<2xf64>>, !fir.ref<!fir.array<2xf64>>)
 ! CHECK-DAG: func.func private @__ldlu_r8x2_(!fir.ref<!fir.array<2xf64>>, !fir.ref<!fir.array<2xf64>>)
 ! CHECK-DAG: func.func private @__ldcv_r8x2_(!fir.ref<!fir.array<2xf64>>, !fir.ref<!fir.array<2xf64>>)
+
+attributes(global) subroutine test_barrier()
+  integer(8), shared :: barrier
+  call barrier_init(barrier, 256)
+end subroutine
+
+
+! CHECK-LABEL: func.func @_QPtest_barrier()
+    
+! CHECK: %[[SHARED:.*]] = cuf.shared_memory i64 {bindc_name = "barrier", uniq_name = "_QFtest_barrierEbarrier"} -> !fir.ref<i64>
+! CHECK: %[[DECL_SHARED:.*]]:2 = hlfir.declare %[[SHARED]] {data_attr = #cuf.cuda<shared>, uniq_name = "_QFtest_barrierEbarrier"} : (!fir.ref<i64>) -> (!fir.ref<i64>, !fir.ref<i64>)
+! CHECK: %[[COUNT:.*]] = arith.constant 256 : i32
+! CHECK: %[[LLVM_PTR:.*]] = fir.convert %[[DECL_SHARED]]#0 : (!fir.ref<i64>) -> !llvm.ptr
+! CHECK: %[[SHARED_PTR:.*]] = llvm.addrspacecast %[[LLVM_PTR]] : !llvm.ptr to !llvm.ptr<3>
+! CHECK: nvvm.mbarrier.init.shared %[[SHARED_PTR]], %[[COUNT]] : !llvm.ptr<3>, i32