[clang] [CIR][OpenMP] Implement lowering for the 'if' clause for 'parallel' d… (PR #204999)

[Pedro da Rosa Pinheiro via cfe-commits]

https://github.com/pedropiin updated https://github.com/llvm/llvm-project/pull/204999

>From 19547508da4845163cbc76ddc23aad6c7edadd07 Mon Sep 17 00:00:00 2001
From: pedropiin <pedarosa04 at gmail.com>
Date: Sun, 21 Jun 2026 15:12:26 -0300
Subject: [PATCH] [CIR][OpenMP] Implement lowering for the 'if' clause for
 'parallel' directive

---
 clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp | 23 ++++++++++++++++++++
 clang/lib/CIR/CodeGen/CIRGenOpenMPClause.h   |  2 ++
 clang/lib/CIR/CodeGen/CIRGenStmtOpenMP.cpp   |  5 +++--
 clang/test/CIR/CodeGenOpenMP/parallel.c      | 22 +++++++++++++++++++
 4 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
index 16ac4440660b5..8155e4697e32d 100644
--- a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.cpp
@@ -93,6 +93,29 @@ bool OpenMPClauseEmitter::emitProcBind(
   return false;
 }
 
+bool OpenMPClauseEmitter::emitIf(mlir::omp::IfClauseOps &result) const {
+  for (const OMPClause *clause : clauses) {
+    const auto *ic = dyn_cast<OMPIfClause>(clause);
+    if (!ic)
+      continue;
+
+    Expr *ifCondition = ic->getCondition();
+    mlir::Value ifBoolValue = cgf.evaluateExprAsBool(ifCondition); // !cir.bool
+
+    mlir::Type uIntType = builder.getUIntNTy(1);
+    mlir::Value ifUIntValue =
+        builder.createBoolToInt(ifBoolValue, uIntType); // u1
+
+    mlir::Type intType = builder.getI1Type();
+    mlir::Value ifExpr =
+        builder.createBuiltinIntCast(ifUIntValue, intType); // i1
+
+    result.ifExpr = ifExpr;
+    return true;
+  }
+  return false;
+}
+
 bool OpenMPClauseEmitter::emitMap(
     mlir::omp::MapClauseOps &result,
     llvm::SmallVectorImpl<const VarDecl *> *mapSyms) const {
diff --git a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.h b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.h
index 54c7366b1d769..ee048296f1946 100644
--- a/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.h
+++ b/clang/lib/CIR/CodeGen/CIRGenOpenMPClause.h
@@ -42,6 +42,8 @@ class OpenMPClauseEmitter {
 
   bool emitProcBind(mlir::omp::ProcBindClauseOps &result) const;
 
+  bool emitIf(mlir::omp::IfClauseOps &result) const;
+
   /// Emit map clauses. The optional \p mapSyms parameter collects the
   /// VarDecls corresponding to each map operand.
   bool emitMap(mlir::omp::MapClauseOps &result,
diff --git a/clang/lib/CIR/CodeGen/CIRGenStmtOpenMP.cpp b/clang/lib/CIR/CodeGen/CIRGenStmtOpenMP.cpp
index 17a1fb8090f5c..4766891dc5b70 100644
--- a/clang/lib/CIR/CodeGen/CIRGenStmtOpenMP.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenStmtOpenMP.cpp
@@ -39,10 +39,11 @@ CIRGenFunction::emitOMPParallelDirective(const OMPParallelDirective &s) {
   mlir::omp::ParallelOperands clauseOps;
   OpenMPClauseEmitter ce(*this, getCIRGenModule(), builder, begin, s.clauses());
   ce.emitProcBind(clauseOps);
-  ce.emitNYI</*supported=*/OMPProcBindClause>(
+  ce.emitIf(clauseOps);
+  ce.emitNYI</*supported=*/OMPProcBindClause, OMPIfClause>(
       /*nyi=*/OpenMPNYIClauseList<
           OMPAllocateClause, OMPCopyinClause, OMPDefaultClause,
-          OMPFirstprivateClause, OMPIfClause, OMPNumThreadsClause,
+          OMPFirstprivateClause, OMPNumThreadsClause,
           OMPPrivateClause, OMPReductionClause, OMPSharedClause>{},
       llvm::omp::Directive::OMPD_parallel);
 
diff --git a/clang/test/CIR/CodeGenOpenMP/parallel.c b/clang/test/CIR/CodeGenOpenMP/parallel.c
index 36a48b38ee789..b3b82fbd3ea23 100644
--- a/clang/test/CIR/CodeGenOpenMP/parallel.c
+++ b/clang/test/CIR/CodeGenOpenMP/parallel.c
@@ -84,3 +84,25 @@ void proc_bind_parallel() {
   // CHECK-NEXT: omp.terminator
   // CHECK-NEXT: }
 }
+
+void if_parallel() {
+  // CHECK: omp.parallel if(%{{.*}}) {
+#pragma omp parallel if (1)
+  {}
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+
+int validCondition = 10;
+  // CHECK: omp.parallel if(%{{.*}}) {
+#pragma omp parallel if (validCondition)
+  {}
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+
+void *nullPtr = ((void *)0);
+  // CHECK: omp.parallel if(%{{.*}}) {
+#pragma omp parallel if (nullPtr)
+  {}
+  // CHECK-NEXT: omp.terminator
+  // CHECK-NEXT: }
+}