[gcc r8-10110] [Fortran] Disable front-end optimization for OpenACC atomic (PR93462)

[Tobias Burnus]

https://gcc.gnu.org/g:6352c50d06a8ca0157293ecb0ef1f8a6dc19148a

commit r8-10110-g6352c50d06a8ca0157293ecb0ef1f8a6dc19148a
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Wed Mar 4 13:29:25 2020 +0100

    [Fortran] Disable front-end optimization for OpenACC atomic (PR93462)
    
    	Backported from mainline
    	2020-01-31  Tobias Burnus  <tobias@codesourcery.com>
    
    	PR fortran/93462
    	* frontend-passes.c (gfc_code_walker): For EXEC_OACC_ATOMIC, set
    	in_omp_atomic to true prevent front-end optimization.
    
    	PR fortran/93462
    	* gfortran.dg/goacc/atomic-1.f90: New.

Diff:
---
 gcc/fortran/ChangeLog                        |  9 +++++++++
 gcc/fortran/frontend-passes.c                |  1 +
 gcc/testsuite/ChangeLog                      |  8 ++++++++
 gcc/testsuite/gfortran.dg/goacc/atomic-1.f90 | 17 +++++++++++++++++
 4 files changed, 35 insertions(+)

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index d3be753..d078dfb 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,12 @@
+2020-02-04  Tobias Burnus  <tobias@codesourcery.com>
+
+	Backported from mainline
+	2020-01-31  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR fortran/93462
+	* frontend-passes.c (gfc_code_walker): For EXEC_OACC_ATOMIC, set
+	in_omp_atomic to true prevent front-end optimization.
+
 2020-03-04  Release Manager
 
 	* GCC 8.4.0 released.
diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index be0fd0f..e317c89 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -4766,6 +4766,7 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t codefn, walk_expr_fn_t exprfn,
 	      WALK_SUBEXPR (co->ext.dt->extra_comma);
 	      break;
 
+	    case EXEC_OACC_ATOMIC:
 	    case EXEC_OMP_ATOMIC:
 	      in_omp_atomic = true;
 	      break;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ab652dd..8a4be39 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2020-02-04  Tobias Burnus  <tobias@codesourcery.com>
+
+	Backported from mainline
+	2020-01-31  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR fortran/93462
+	* gfortran.dg/goacc/atomic-1.f90: New.
+
 2020-03-04  Release Manager
 
 	* GCC 8.4.0 released.
diff --git a/gcc/testsuite/gfortran.dg/goacc/atomic-1.f90 b/gcc/testsuite/gfortran.dg/goacc/atomic-1.f90
new file mode 100644
index 0000000..579f049
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/goacc/atomic-1.f90
@@ -0,0 +1,17 @@
+! { dg-do compile }
+!
+! PR fortran/93462
+!
+! Contributed by G. Steinmetz
+!
+program p
+   integer :: n = 1
+   integer :: a
+!$acc atomic write
+   a = f(n) - f(n)
+contains
+   integer function f(x)
+      integer, intent(in) :: x
+      f = x
+   end
+end