From 89275300d861aef73225428c95fdb069de36186d Mon Sep 17 00:00:00 2001
From: Valentin Clement <clementval@gmail.com>
Date: Tue, 1 Feb 2022 15:26:47 +0100
Subject: [PATCH] [flang] Add lowering for basic empty SUBROUTINE

This patch adds the ability to lower an empty subroutine.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D118695
---
 flang/lib/Lower/Bridge.cpp            | 16 +++++++++++++---
 flang/test/Lower/basic-subroutine.f90 | 13 +++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 flang/test/Lower/basic-subroutine.f90

diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 3645152..fdd4225 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -175,6 +175,8 @@ public:
     setCurrentPosition(Fortran::lower::pft::stmtSourceLoc(funit.endStmt));
     if (funit.isMainProgram())
       genExitRoutine();
+    else
+      genFIRProcedureExit(funit, funit.getSubprogramSymbol());
     funit.finalBlock = nullptr;
     LLVM_DEBUG(llvm::dbgs() << "*** Lowering result:\n\n"
                             << *builder->getFunction() << '\n');
@@ -240,6 +242,15 @@ private:
   }
   void genFIR(const Fortran::parser::EndProgramStmt &) { genExitRoutine(); }
 
+  void genFIRProcedureExit(Fortran::lower::pft::FunctionLikeUnit &funit,
+                           const Fortran::semantics::Symbol &symbol) {
+    if (Fortran::semantics::IsFunction(symbol)) {
+      TODO(toLocation(), "Function lowering");
+    } else {
+      genExitRoutine();
+    }
+  }
+
   void genFIR(const Fortran::parser::CallStmt &stmt) {
     TODO(toLocation(), "CallStmt lowering");
   }
@@ -606,9 +617,8 @@ private:
     TODO(toLocation(), "EndSelectStmt lowering");
   }
 
-  void genFIR(const Fortran::parser::EndSubroutineStmt &) {
-    TODO(toLocation(), "EndSubroutineStmt lowering");
-  }
+  // Nop statements - No code, or code is generated at the construct level.
+  void genFIR(const Fortran::parser::EndSubroutineStmt &) {} // nop
 
   void genFIR(const Fortran::parser::EntryStmt &) {
     TODO(toLocation(), "EntryStmt lowering");
diff --git a/flang/test/Lower/basic-subroutine.f90 b/flang/test/Lower/basic-subroutine.f90
new file mode 100644
index 0000000..aaa37d7
--- /dev/null
+++ b/flang/test/Lower/basic-subroutine.f90
@@ -0,0 +1,13 @@
+! RUN: bbc %s --pft-test | FileCheck %s
+! RUN: bbc %s -o "-" -emit-fir | FileCheck %s --check-prefix=FIR
+
+subroutine sub1()
+end subroutine
+
+! CHECK: 1 Subroutine sub1: subroutine sub1()
+! CHECK:   1 EndSubroutineStmt: end subroutine
+! CHECK: End Subroutine sub1
+
+! FIR-LABEL: func @_QPsub1() {
+! FIR:         return
+! FIR:       }
-- 
2.7.4