From db01b123d012df2f0e6acf7e90bf4ba63382587c Mon Sep 17 00:00:00 2001
From: Valentin Clement <clementval@gmail.com>
Date: Wed, 2 Feb 2022 08:15:26 +0100
Subject: [PATCH] [flang] Lower PAUSE statement

Lower the PAUSE statement to a runtime call.

This patch is part of the upstreaming effort from fir-dev branch.

Reviewed By: kiranchandramohan, schweitz

Differential Revision: https://reviews.llvm.org/D118699

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>
---
 flang/lib/Lower/Bridge.cpp           |  2 +-
 flang/lib/Lower/Runtime.cpp          | 10 ++++++++++
 flang/test/Lower/pause-statement.f90 |  8 ++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Lower/pause-statement.f90

diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index fd52a76cf2f6..7302f6c8ce66 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -547,7 +547,7 @@ private:
   }
 
   void genFIR(const Fortran::parser::PauseStmt &stmt) {
-    TODO(toLocation(), "PauseStmt lowering");
+    genPauseStatement(*this, stmt);
   }
 
   void genFIR(const Fortran::parser::FailImageStmt &stmt) {
diff --git a/flang/lib/Lower/Runtime.cpp b/flang/lib/Lower/Runtime.cpp
index 7156a8851f1d..a49b0911d1a1 100644
--- a/flang/lib/Lower/Runtime.cpp
+++ b/flang/lib/Lower/Runtime.cpp
@@ -68,3 +68,13 @@ void Fortran::lower::genStopStatement(
   builder.create<fir::CallOp>(loc, callee, operands);
   genUnreachable(builder, loc);
 }
+
+void Fortran::lower::genPauseStatement(
+    Fortran::lower::AbstractConverter &converter,
+    const Fortran::parser::PauseStmt &) {
+  fir::FirOpBuilder &builder = converter.getFirOpBuilder();
+  mlir::Location loc = converter.getCurrentLocation();
+  mlir::FuncOp callee =
+      fir::runtime::getRuntimeFunc<mkRTKey(PauseStatement)>(loc, builder);
+  builder.create<fir::CallOp>(loc, callee, llvm::None);
+}
diff --git a/flang/test/Lower/pause-statement.f90 b/flang/test/Lower/pause-statement.f90
new file mode 100644
index 000000000000..e4cba98dc8a7
--- /dev/null
+++ b/flang/test/Lower/pause-statement.f90
@@ -0,0 +1,8 @@
+! RUN: bbc %s -emit-fir --canonicalize -o - | FileCheck %s
+
+! CHECK-LABEL pause_test
+subroutine pause_test()
+  ! CHECK: fir.call @_Fortran{{.*}}PauseStatement()
+  ! CHECK-NEXT: return
+  pause
+end subroutine