[Mlir-commits] [mlir] 13cd881 - [mlir][OpenMP] - Honor dependencies in code-generation of the if clause in `omp.task` correctly (#90891)

[llvmlistbot at llvm.org]

Author: Pranav Bhandarkar
Date: 2024-05-13T08:54:23-05:00
New Revision: 13cd88108f00fc97bcd1e4eb7cc9e4e388928677

URL: https://github.com/llvm/llvm-project/commit/13cd88108f00fc97bcd1e4eb7cc9e4e388928677
DIFF: https://github.com/llvm/llvm-project/commit/13cd88108f00fc97bcd1e4eb7cc9e4e388928677.diff

LOG: [mlir][OpenMP] - Honor dependencies in code-generation of the if clause in `omp.task` correctly (#90891)

This patch fixes the code generation of the if clause, specifically when the
condition evaluates to false and when the task directive has the depend
clause on it. When the if clause of a task construct evaluates to false,
then the task is an undeferred task. This undeferred task still has to
honor dependencies. Previously, the OpenMPIRbuilder didn't honor
dependencies. This patch fixes that.

Fixes https://github.com/llvm/llvm-project/issues/90869

Added: 
    mlir/test/Target/LLVMIR/omptask_if_false.mlir

Modified: 
    llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index 42ea20919a5e1..391a4947877a6 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -1870,6 +1870,9 @@ OpenMPIRBuilder::createTask(const LocationDescription &Loc,
     //    call @__kmpc_omp_task(...)
     //    br label %exit
     //  else:
+    //    ;; Wait for resolution of dependencies, if any, before
+    //    ;; beginning the task
+    //    call @__kmpc_omp_wait_deps(...)
     //    call @__kmpc_omp_task_begin_if0(...)
     //    call @outlined_fn(...)
     //    call @__kmpc_omp_task_complete_if0(...)
@@ -1887,6 +1890,16 @@ OpenMPIRBuilder::createTask(const LocationDescription &Loc,
       SplitBlockAndInsertIfThenElse(IfCondition, IfTerminator, &ThenTI,
                                     &ElseTI);
       Builder.SetInsertPoint(ElseTI);
+
+      if (Dependencies.size()) {
+        Function *TaskWaitFn =
+            getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_wait_deps);
+        Builder.CreateCall(
+            TaskWaitFn,
+            {Ident, ThreadID, Builder.getInt32(Dependencies.size()), DepArray,
+             ConstantInt::get(Builder.getInt32Ty(), 0),
+             ConstantPointerNull::get(PointerType::getUnqual(M.getContext()))});
+      }
       Function *TaskBeginFn =
           getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task_begin_if0);
       Function *TaskCompleteFn =

diff  --git a/mlir/test/Target/LLVMIR/omptask_if_false.mlir b/mlir/test/Target/LLVMIR/omptask_if_false.mlir
new file mode 100644
index 0000000000000..c6014a76add6d
--- /dev/null
+++ b/mlir/test/Target/LLVMIR/omptask_if_false.mlir
@@ -0,0 +1,17 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+llvm.func @foo_(%arg0: !llvm.ptr {fir.bindc_name = "n"}, %arg1: !llvm.ptr {fir.bindc_name = "r"}) attributes {fir.internal_name = "_QPfoo"} {
+  %0 = llvm.mlir.constant(false) : i1
+  omp.task if(%0) depend(taskdependin -> %arg0 : !llvm.ptr) {
+    %1 = llvm.load %arg0 : !llvm.ptr -> i32
+    llvm.store %1, %arg1 : i32, !llvm.ptr
+    omp.terminator
+  }
+  llvm.return
+}
+
+// CHECK: call void @__kmpc_omp_wait_deps
+// CHECK-NEXT: call void @__kmpc_omp_task_begin_if0
+// CHECK-NEXT: call void @foo_..omp_par
+// CHECK-NEXT: call void @__kmpc_omp_task_complete_if0
+