[clang] [OpenMP][CIR] Implement 'parallel's 'proc_bind' clause lowering (PR #172501)

[Erich Keane via cfe-commits]

https://github.com/erichkeane created https://github.com/llvm/llvm-project/pull/172501

This patch implements the 'first' clause for OMP, which is the 'proc_bind' clause. This clause takes one of a handful of values and just passes it onto the OMP dialect.

The 'default' value for this isn't present in the OMP dialect, however the classic-codegen doesn't generate the library call when this value is passed, so this is effectively a 'no-op'.

>From fe6afb5e9ba004f6e7010fd292ad3c22365b3cc3 Mon Sep 17 00:00:00 2001
From: erichkeane <ekeane at nvidia.com>
Date: Fri, 12 Dec 2025 10:42:27 -0800
Subject: [PATCH] [OpenMP][CIR] Implement 'parallel's 'proc_bind' clause
 lowering

This patch implements the 'first' clause for OMP, which is the
'proc_bind' clause. This clause takes one of a handful of values and
just passes it onto the OMP dialect.

The 'default' value for this isn't present in the OMP dialect, however
the classic-codegen doesn't generate the library call when this value is
passed, so this is effectively a 'no-op'.
---
 clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp | 32 ++++++++++++++++++++
 clang/test/CIR/CodeGenOpenMP/parallel.c      | 28 +++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
index f73c0c4000d7e..8c1c3323b37f1 100644
--- a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
@@ -34,6 +34,38 @@ class OpenMPClauseCIREmitter final
                      clause->getClauseKind());
   }
 
+  void VisitOMPProcBindClause(const OMPProcBindClause *clause) {
+    if constexpr (std::is_same_v<OpTy, mlir::omp::ParallelOp>) {
+      mlir::omp::ClauseProcBindKind kind;
+      switch (clause->getProcBindKind()) {
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_master:
+        kind = mlir::omp::ClauseProcBindKind::Master;
+        break;
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_close:
+        kind = mlir::omp::ClauseProcBindKind::Close;
+        break;
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_spread:
+        kind = mlir::omp::ClauseProcBindKind::Spread;
+        break;
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_primary:
+        kind = mlir::omp::ClauseProcBindKind::Primary;
+        break;
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_default:
+        // 'default' in the classic-codegen does no runtime call/doesn't
+        // really do anything. So this is a no-op, and thus shouldn't change
+        // the IR.
+        return;
+      case llvm::omp::ProcBindKind::OMP_PROC_BIND_unknown:
+        llvm_unreachable("unknown proc-bind kind");
+      }
+      operation.setProcBindKind(kind);
+    } else {
+      cgf.cgm.errorNYI(
+          clause->getBeginLoc(),
+          "OMPProcBindClause unimplemented on this directive kind");
+    }
+  }
+
   void emitClauses(ArrayRef<const OMPClause *> clauses) {
     for (const auto *c : clauses)
       this->Visit(c);
diff --git a/clang/test/CIR/CodeGenOpenMP/parallel.c b/clang/test/CIR/CodeGenOpenMP/parallel.c
index 84095bd994fac..a2bfc8f4ce82e 100644
--- a/clang/test/CIR/CodeGenOpenMP/parallel.c
+++ b/clang/test/CIR/CodeGenOpenMP/parallel.c
@@ -48,3 +48,31 @@ void parallel_with_operations() {
   // CHECK-NEXT: omp.terminator
   // CHECK-NEXT: }
 }
+void proc_bind_parallel() {
+  // CHECK: cir.func{{.*}}@proc_bind_parallel
+#pragma omp parallel proc_bind(master)
+  {}
+  // CHECK-NEXT: omp.parallel proc_bind(master) {
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+#pragma omp parallel proc_bind(close)
+  {}
+  // CHECK-NEXT: omp.parallel proc_bind(close) {
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+#pragma omp parallel proc_bind(spread)
+  {}
+  // CHECK-NEXT: omp.parallel proc_bind(spread) {
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+#pragma omp parallel proc_bind(primary)
+  {}
+  // CHECK-NEXT: omp.parallel proc_bind(primary) {
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+#pragma omp parallel proc_bind(default)
+  {}
+  // CHECK-NEXT: omp.parallel {
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+}