[Clang][OpenMP] Fix the issue that a functor is not captured properly in a task region

[tianshilei1992]

Summary

This patch fixes the issue that a functor is not captured properly if
that is used in a task region. It was introduced by https://reviews.llvm.org/D114546
where CallExpr is treated specially, but the callee itself is not properly visited.
https://reviews.llvm.org/D115902 already did some fix for one case. This patch
fixes another case.

Fix #57757.

[ABataev]

LG

clang/lib/Sema/SemaOpenMP.cpp

public:
   void VisitCallExpr(CallExpr *S) {
     for (Stmt *C : S->arguments()) {
       if (C) {
         // Check implicitly captured variables in the task-based directives to
         // check if they must be firstprivatized.
         Visit(C);
       }
     }
-    if (Expr *Callee = S->getCallee())
-      if (auto *CE = dyn_cast<MemberExpr>(Callee->IgnoreParenImpCasts()))
+    if (Expr *Callee = S->getCallee()) {
+      auto *CI = Callee->IgnoreParenImpCasts();
+      if (auto *CE = dyn_cast<MemberExpr>(CI))
         Visit(CE->getBase());
+      else if (auto *CE = dyn_cast<DeclRefExpr>(CI))
+        Visit(CE);
+    }
   }
   void VisitStmt(Stmt *S) {
     for (Stmt *C : S->children()) {
       if (C) {
         // Check implicitly captured variables in the task-based directives to
         // check if they must be firstprivatized.
         Visit(C);
       }

clang/test/OpenMP/bug57757.cpp

+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --function-signature --include-generated-funcs --prefix-filecheck-ir-name _
+// RUN: %clang_cc1 -fopenmp -O1 -x c++ -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK
+
+template <class Function, class... Args>
+void run_task(Function function, Args... args) {
+#pragma omp task untied
+  { function(args...); }
+}
+
+void bar(int a, float b);
+
+void foo() {
+  int a;
+  float b;
+  run_task(bar, a, b);
+}
+// CHECK-LABEL: define {{[^@]+}}@_Z3foov
+// CHECK-SAME: () local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP0:%.*]] = tail call i32 @__kmpc_global_thread_num(ptr nonnull @[[GLOB1:[0-9]+]])
+// CHECK-NEXT:    [[TMP1:%.*]] = tail call ptr @__kmpc_omp_task_alloc(ptr nonnull @[[GLOB1]], i32 [[TMP0]], i32 0, i64 56, i64 1, ptr nonnull @.omp_task_entry.)
+// CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T_WITH_PRIVATES:%.*]], ptr [[TMP1]], i64 0, i32 1
+// CHECK-NEXT:    store ptr @_Z3barif, ptr [[TMP2]], align 8, !tbaa [[TBAA3:![0-9]+]]
+// CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T:%.*]], ptr [[TMP1]], i64 0, i32 2
+// CHECK-NEXT:    store i32 0, ptr [[TMP3]], align 8, !tbaa [[TBAA12:![0-9]+]]
+// CHECK-NEXT:    [[TMP4:%.*]] = tail call i32 @__kmpc_omp_task(ptr nonnull @[[GLOB1]], i32 [[TMP0]], ptr [[TMP1]])
+// CHECK-NEXT:    ret void
+//
+//
+// CHECK-LABEL: define {{[^@]+}}@.omp_task_entry.
+// CHECK-SAME: (i32 noundef [[TMP0:%.*]], ptr noalias noundef [[TMP1:%.*]]) #[[ATTR3:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T:%.*]], ptr [[TMP1]], i64 0, i32 2
+// CHECK-NEXT:    tail call void @llvm.experimental.noalias.scope.decl(metadata [[META13:![0-9]+]])
+// CHECK-NEXT:    tail call void @llvm.experimental.noalias.scope.decl(metadata [[META16:![0-9]+]])
+// CHECK-NEXT:    [[TMP3:%.*]] = load i32, ptr [[TMP2]], align 4, !tbaa [[TBAA18:![0-9]+]], !alias.scope !13, !noalias !16
+// CHECK-NEXT:    switch i32 [[TMP3]], label [[DOTOMP_OUTLINED__EXIT:%.*]] [
+// CHECK-NEXT:    i32 0, label [[DOTUNTIED_JMP__I:%.*]]
+// CHECK-NEXT:    i32 1, label [[DOTUNTIED_NEXT__I:%.*]]
+// CHECK-NEXT:    ]
+// CHECK:       .untied.jmp..i:
+// CHECK-NEXT:    store i32 1, ptr [[TMP2]], align 4, !tbaa [[TBAA18]], !alias.scope !13, !noalias !16
+// CHECK-NEXT:    [[TMP4:%.*]] = tail call i32 @__kmpc_omp_task(ptr nonnull @[[GLOB1]], i32 [[TMP0]], ptr [[TMP1]]), !noalias !19
+// CHECK-NEXT:    br label [[DOTOMP_OUTLINED__EXIT]]
+// CHECK:       .untied.next..i:
+// CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T_WITH_PRIVATES:%.*]], ptr [[TMP1]], i64 0, i32 1
+// CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T_WITH_PRIVATES]], ptr [[TMP1]], i64 0, i32 1, i32 2
+// CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds [[STRUCT_KMP_TASK_T_WITH_PRIVATES]], ptr [[TMP1]], i64 0, i32 1, i32 1
+// CHECK-NEXT:    [[TMP8:%.*]] = load ptr, ptr [[TMP5]], align 8, !tbaa [[TBAA20:![0-9]+]], !alias.scope !16, !noalias !13
+// CHECK-NEXT:    [[TMP9:%.*]] = load i32, ptr [[TMP7]], align 4, !tbaa [[TBAA18]], !alias.scope !16, !noalias !13
+// CHECK-NEXT:    [[TMP10:%.*]] = load float, ptr [[TMP6]], align 4, !tbaa [[TBAA21:![0-9]+]], !alias.scope !16, !noalias !13
+// CHECK-NEXT:    tail call void [[TMP8]](i32 noundef [[TMP9]], float noundef [[TMP10]]) #[[ATTR2:[0-9]+]], !noalias !19
+// CHECK-NEXT:    br label [[DOTOMP_OUTLINED__EXIT]]
+// CHECK:       .omp_outlined..exit:
+// CHECK-NEXT:    ret i32 0
+//