[gcc r13-2839] fortran: Support clobbering of ASSOCIATE variables [PR41453]

[Mikael Morin <mikael@gcc.gnu.org>]

https://gcc.gnu.org/g:d5e1935b09fa05093e31d7ce5e21b7e71957c103

commit r13-2839-gd5e1935b09fa05093e31d7ce5e21b7e71957c103
Author: Mikael Morin <mikael@gcc.gnu.org>
Date:   Wed Aug 31 11:58:08 2022 +0200

    fortran: Support clobbering of ASSOCIATE variables [PR41453]
    
    This is in spirit a revert of:
    r9-3051-gc109362313623d83fe0a5194bceaf994cf0c6ce0
    
    That commit added a condition to avoid generating ICE with clobbers
    of ASSOCIATE variables.
    The test added at that point continues to pass if we remove that
    condition now.
    
            PR fortran/41453
            PR fortran/87401
    
    gcc/fortran/ChangeLog:
    
            * trans-expr.cc (gfc_conv_procedure_call): Remove condition
            disabling clobber generation for ASSOCIATE variables.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/intent_optimize_8.f90: New test.

Diff:
---
 gcc/fortran/trans-expr.cc                       |  1 -
 gcc/testsuite/gfortran.dg/intent_optimize_8.f90 | 45 +++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 10b49347587..c2c7382c7d7 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -6527,7 +6527,6 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 			  && !e->symtree->n.sym->attr.dimension
 			  && !e->symtree->n.sym->attr.pointer
 			  && !e->symtree->n.sym->attr.allocatable
-			  && !e->symtree->n.sym->attr.associate_var
 			  && e->ts.type != BT_CHARACTER
 			  && e->ts.type != BT_DERIVED
 			  && e->ts.type != BT_CLASS
diff --git a/gcc/testsuite/gfortran.dg/intent_optimize_8.f90 b/gcc/testsuite/gfortran.dg/intent_optimize_8.f90
new file mode 100644
index 00000000000..4336fceab02
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/intent_optimize_8.f90
@@ -0,0 +1,45 @@
+! { dg-do run }
+! { dg-additional-options "-fno-inline -fno-ipa-modref -fdump-tree-optimized -fdump-tree-original" }
+!
+! PR fortran/41453
+! Check that the INTENT(OUT) attribute causes one clobber to be emitted in
+! the caller before each call to FOO in the *.original dump, and the
+! initialization constants to be optimized away in the *.optimized dump,
+! in the case of associate variables.
+
+module x
+implicit none
+contains
+  subroutine foo(a)
+    integer, intent(out) :: a
+    a = 42
+  end subroutine foo
+end module x
+
+program main
+  use x
+  implicit none
+  integer :: c1, c2
+
+  c1 = 123456789
+  associate (d1 => c1)
+    call foo(d1)
+    if (d1 /= 42) stop 1
+  end associate
+  if (c1 /= 42) stop 2
+
+  c2 = 0
+  associate (d2 => c2)
+    d2 = 987654321
+    call foo(d2)
+    if (d2 /= 42) stop 3
+  end associate
+  if (c2 /= 42) stop 4
+
+end program main
+
+! { dg-final { scan-tree-dump-times "CLOBBER" 2 "original" } }
+! { dg-final { scan-tree-dump "d1 = {CLOBBER};" "original" } }
+! { dg-final { scan-tree-dump "\\*d2 = {CLOBBER};" "original" } }
+! { dg-final { scan-tree-dump-not "123456789" "optimized" { target __OPTIMIZE__ } } }
+! { dg-final { scan-tree-dump-not "987654321" "optimized" { target __OPTIMIZE__ } } }