Dear all,
gfortran stores PARAMETERS which are array or derived types as global
static variable. This prevents the compiler from optimizing those
parameters.
Using TREE_READONLY, one can allow the compiler to make use of the
values and do further optimizations.
Build and regtested on x86_64-linux.
OK for the trunk?
Tobias
2011-11-03 Tobias Burnus <bur...@net-b.de>
PR fortran/50960
* trans-decl.c (gfc_finish_var_decl): Mark PARAMETER as TREE_READONLY.
2011-11-03 Tobias Burnus <bur...@net-b.de>
PR fortran/50960
* gfortran.dg/module_parameter_array_refs_2.f90: New.
diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index b7460b7..b90b0ab 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -517,6 +517,10 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
/* If it wasn't used we wouldn't be getting it. */
TREE_USED (decl) = 1;
+ if (sym->attr.flavor == FL_PARAMETER
+ && (sym->attr.dimension || sym->ts.type == BT_DERIVED))
+ TREE_READONLY (decl) = 1;
+
/* Chain this decl to the pending declarations. Don't do pushdecl()
because this would add them to the current scope rather than the
function scope. */
--- /dev/null 2011-11-01 08:51:46.775606868 +0100
+++ gcc/gcc/testsuite/gfortran.dg/module_parameter_array_refs_2.f90 2011-11-03 21:59:20.000000000 +0100
@@ -0,0 +1,23 @@
+! { dg-do compile }
+! { dg-options "-O" }
+! { dg-final { scan-assembler-not "i_am_optimized_away" } }
+!
+! PR fortran/50960
+!
+! PARAMETER arrays and derived types exists as static variables.
+! Check that the their read-only nature is taken into account
+! when optimizations are done.
+!
+
+module m
+ integer, parameter :: PARA(*) = [1,2,3,4,5,6,7,8,9,10]
+end module m
+
+subroutine test()
+use m
+integer :: i
+i = 1
+if (para(i) /= 1) call i_am_optimized_away()
+end
+
+! { dg-final { cleanup-modules "m" } }
