[Mlir-commits] [mlir] [Flang][OpenMP] Declare Target fixes for USM and declare target to (PR #200248)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Thu May 28 19:06:09 PDT 2026
https://github.com/agozillon updated https://github.com/llvm/llvm-project/pull/200248
>From a69578540e03c79894ba753e52042648bed47e72 Mon Sep 17 00:00:00 2001
From: agozillon <Andrew.Gozillon at amd.com>
Date: Thu, 28 May 2026 13:16:02 -0500
Subject: [PATCH] [Flang][OpenMP] Declare Target fixes for USM and declare
target to
Currently declare target enter would fall through the if statement even though it's a synonym of
declare target to, so fix this via adding a simpler and more readable check for link clause instead.
USM declare target to works a little differently to regular link cases, where the type is actually
converted into a pointer, rather than a global of the original typing. So, add a caveat where we
convert the type to a pointer if requires usm has been triggered. This gets the correct behaviour
in USM mode on USM devices.
---
.../OpenMP/OpenMPToLLVMIRTranslation.cpp | 45 +++++++++--------
...mptarget-declare-target-llvm-device-2.mlir | 50 +++++++++++++++++++
2 files changed, 73 insertions(+), 22 deletions(-)
create mode 100644 mlir/test/Target/LLVMIR/omptarget-declare-target-llvm-device-2.mlir
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index f0511bb4be7dd..389575c691386 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -5426,25 +5426,20 @@ getRefPtrIfDeclareTarget(Value value,
llvm::OpenMPIRBuilder *ompBuilder = moduleTranslation.getOpenMPBuilder();
if (auto gOp =
dyn_cast_or_null<LLVM::GlobalOp>(getGlobalOpFromValue(value))) {
- if (auto declareTargetGlobal =
- dyn_cast<omp::DeclareTargetInterface>(gOp.getOperation())) {
- // In this case, we must utilise the reference pointer generated by
- // the declare target operation, similar to Clang
- if ((declareTargetGlobal.getDeclareTargetCaptureClause() ==
- omp::DeclareTargetCaptureClause::link) ||
- (declareTargetGlobal.getDeclareTargetCaptureClause() ==
- omp::DeclareTargetCaptureClause::to &&
- ompBuilder->Config.hasRequiresUnifiedSharedMemory())) {
- llvm::SmallString<64> suffix = getDeclareTargetRefPtrSuffix(
- gOp, *ompBuilder, moduleTranslation.getFileSystem());
-
- if (gOp.getSymName().contains(suffix))
- return moduleTranslation.getLLVMModule()->getNamedValue(
- gOp.getSymName());
-
+ // In this case, we must utilise the reference pointer generated by
+ // the declare target operation, similar to Clang
+ if (isDeclareTargetLink(value) ||
+ (isDeclareTargetTo(value) &&
+ ompBuilder->Config.hasRequiresUnifiedSharedMemory())) {
+ llvm::SmallString<64> suffix = getDeclareTargetRefPtrSuffix(
+ gOp, *ompBuilder, moduleTranslation.getFileSystem());
+
+ if (gOp.getSymName().contains(suffix))
return moduleTranslation.getLLVMModule()->getNamedValue(
- (gOp.getSymName().str() + suffix.str()).str());
- }
+ gOp.getSymName());
+
+ return moduleTranslation.getLLVMModule()->getNamedValue(
+ (gOp.getSymName().str() + suffix.str()).str());
}
}
return nullptr;
@@ -8171,15 +8166,21 @@ convertDeclareTargetAttr(Operation *op, mlir::omp::DeclareTargetAttr attribute,
/*GlobalInitializer*/ nullptr, /*VariableLinkage*/ nullptr,
gVal->getType(), gVal);
+ bool requiresUSM = ompBuilder->Config.hasRequiresUnifiedSharedMemory();
if (ompBuilder->Config.isTargetDevice() &&
- (attribute.getCaptureClause().getValue() !=
- mlir::omp::DeclareTargetCaptureClause::to ||
- ompBuilder->Config.hasRequiresUnifiedSharedMemory())) {
+ (attribute.getCaptureClause().getValue() ==
+ mlir::omp::DeclareTargetCaptureClause::link ||
+ requiresUSM)) {
+ llvm::Type *ptrTy = gVal->getType();
+ // For USM the global type becomes a pointer handle, as opposed to the
+ // globals original type.
+ if (requiresUSM)
+ ptrTy = llvm::PointerType::get(llvmModule->getContext(), 0);
ompBuilder->getAddrOfDeclareTargetVar(
captureClause, deviceClause, isDeclaration, isExternallyVisible,
ompBuilder->getTargetEntryUniqueInfo(fileInfoCallBack, vfs),
mangledName, generatedRefs, /*OpenMPSimd*/ false, targetTriple,
- gVal->getType(), /*GlobalInitializer*/ nullptr,
+ ptrTy, /*GlobalInitializer*/ nullptr,
/*VariableLinkage*/ nullptr);
}
}
diff --git a/mlir/test/Target/LLVMIR/omptarget-declare-target-llvm-device-2.mlir b/mlir/test/Target/LLVMIR/omptarget-declare-target-llvm-device-2.mlir
new file mode 100644
index 0000000000000..6969f3030cba8
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/omptarget-declare-target-llvm-device-2.mlir
@@ -0,0 +1,50 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+// This test checks that we correctly generate ref pointers with the correct type in USM mode
+// for link and to clauses. And verifies we continue to make the correct replacement accesses
+// within the target region.
+
+module attributes {llvm.target_triple = "amdgcn-amd-amdhsa", omp.is_target_device = true, omp.requires = #omp<clause_requires unified_shared_memory>} {
+ // CHECK-DAG: @_QMtest_0Evar_to_usm_decl_tgt_ref_ptr = weak global ptr null, align 8
+ llvm.mlir.global external @_QMtest_0Evar_to_usm() {addr_space = 0 : i32, omp.declare_target = #omp.declaretarget<device_type = (any), capture_clause = (to)>} : i32 {
+ %0 = llvm.mlir.constant(1 : i32) : i32
+ llvm.return %0 : i32
+ }
+
+ // CHECK-DAG: @_QMtest_0Evar_enter_usm_decl_tgt_ref_ptr = weak global ptr null, align 8
+ llvm.mlir.global external @_QMtest_0Evar_enter_usm() {addr_space = 0 : i32, omp.declare_target = #omp.declaretarget<device_type = (any), capture_clause = (enter)>} : i32 {
+ %0 = llvm.mlir.constant(2 : i32) : i32
+ llvm.return %0 : i32
+ }
+
+ // CHECK-DAG: @_QMtest_0Evar_link_usm_decl_tgt_ref_ptr = weak global ptr null, align 8
+ llvm.mlir.global external @_QMtest_0Evar_link_usm() {addr_space = 0 : i32, omp.declare_target = #omp.declaretarget<device_type = (any), capture_clause = (link)>} : i32 {
+ %0 = llvm.mlir.constant(3 : i32) : i32
+ llvm.return %0 : i32
+ }
+
+ llvm.func @test_usm_declare_target() attributes {} {
+ %0 = llvm.mlir.addressof @_QMtest_0Evar_to_usm : !llvm.ptr
+ %1 = llvm.mlir.addressof @_QMtest_0Evar_enter_usm : !llvm.ptr
+ %2 = llvm.mlir.addressof @_QMtest_0Evar_link_usm : !llvm.ptr
+ // CHECK-DAG: %[[TO_VAR:.*]] = load ptr, ptr @_QMtest_0Evar_to_usm_decl_tgt_ref_ptr, align 8
+ // CHECK-DAG: store i32 10, ptr %[[TO_VAR]], align 4
+ // CHECK-DAG: %[[ENTER_VAR:.*]] = load ptr, ptr @_QMtest_0Evar_enter_usm_decl_tgt_ref_ptr, align 8
+ // CHECK-DAG: store i32 20, ptr %[[ENTER_VAR]], align 4
+ // CHECK-DAG: %[[LINK_VAR:.*]] = load ptr, ptr @_QMtest_0Evar_link_usm_decl_tgt_ref_ptr, align 8
+ // CHECK-DAG: store i32 30, ptr %[[LINK_VAR]], align 4
+ %map0 = omp.map.info var_ptr(%0 : !llvm.ptr, i32) map_clauses(tofrom) capture(ByRef) -> !llvm.ptr {name = ""}
+ %map1 = omp.map.info var_ptr(%1 : !llvm.ptr, i32) map_clauses(tofrom) capture(ByRef) -> !llvm.ptr {name = ""}
+ %map2 = omp.map.info var_ptr(%2 : !llvm.ptr, i32) map_clauses(tofrom) capture(ByRef) -> !llvm.ptr {name = ""}
+ omp.target map_entries(%map0 -> %arg0, %map1 -> %arg1, %map2 -> %arg2 : !llvm.ptr, !llvm.ptr, !llvm.ptr) {
+ %c10 = llvm.mlir.constant(10 : i32) : i32
+ %c20 = llvm.mlir.constant(20 : i32) : i32
+ %c30 = llvm.mlir.constant(30 : i32) : i32
+ llvm.store %c10, %arg0 : i32, !llvm.ptr
+ llvm.store %c20, %arg1 : i32, !llvm.ptr
+ llvm.store %c30, %arg2 : i32, !llvm.ptr
+ omp.terminator
+ }
+ llvm.return
+ }
+}
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