[flang] Lower PAUSE statement

[clementval]

Summary

Lower the PAUSE statement to a runtime call.

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

Co-authored-by: Eric Schweitz <[e-mail]>
Co-authored-by: Jean Perier <[e-mail]>

[kiranchandramohan]

Could you check why the patch application fails?

flang/test/Lower/pause-statement.f90

2

Nit: is canonicalize required?

[clementval]

flang/test/Lower/pause-statement.f90

2

Does not make a difference on this particular test.

[clementval]

Rebase

[clementval]

Update test

[clementval]

In D118699#3287328, @kiranchandramohan wrote:

Could you check why the patch application fails?

Probably too late to add the dependency. Should be fine after the rebase.

[kiranchandramohan]

LGTM.

[clementval]

Rebase

flang/lib/Lower/Bridge.cpp

void genFIR(const Fortran::parser::AssignStmt &stmt) {
     TODO(toLocation(), "AssignStmt lowering");
   }
 
   void genFIR(const Fortran::parser::FormatStmt &) {
     TODO(toLocation(), "FormatStmt lowering");
   }
 
   void genFIR(const Fortran::parser::PauseStmt &stmt) {
-    TODO(toLocation(), "PauseStmt lowering");
+    genPauseStatement(*this, stmt);
   }
 
   void genFIR(const Fortran::parser::FailImageStmt &stmt) {
     TODO(toLocation(), "FailImageStmt lowering");
   }
 
   // call STOP, ERROR STOP in runtime
   void genFIR(const Fortran::parser::StopStmt &stmt) {

flang/lib/Lower/Runtime.cpp

void Fortran::lower::genStopStatement(
   } else {
     operands.push_back(builder.createIntegerConstant(
         loc, calleeType.getInput(operands.size()), 0));
   }
 
   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);
+}

flang/test/Lower/pause-statement.f90

+! 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