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[PATCH,fortran] PR 91413 Generate warning when making array static
- From: Janne Blomqvist <blomqvist dot janne at gmail dot com>
- To: fortran at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
- Cc: Janne Blomqvist <blomqvist dot janne at gmail dot com>
- Date: Sat, 10 Aug 2019 23:34:15 +0300
- Subject: [PATCH,fortran] PR 91413 Generate warning when making array static
When moving a local variable from the stack to static storage, the
procedure is no longer safe to be called recursively or concurrently
from multiple threads. Thus generate a warning when this is done.
Also double the default limit for switching from stack to static.
Regtested on x86_64-pc-linux-gnu, Ok for trunk?
gcc/fortran/ChangeLog:
2019-08-10 Janne Blomqvist <jb@gcc.gnu.org>
PR fortran/91413
* invoke.texi (-fmax-stack-var-size): Document increased default.
* options.c (gfc_post_options): Increase default stack var size to
65536 bytes.
* trans-decl.c (gfc_finish_var_decl): Generate warning when local
array moved to static storage.
---
gcc/fortran/invoke.texi | 2 +-
gcc/fortran/options.c | 2 +-
gcc/fortran/trans-decl.c | 10 ++++++++++
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index 3c1b2ac7a26..1039c6084c4 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -1720,7 +1720,7 @@ This option currently only affects local arrays declared with constant
bounds, and may not apply to all character variables.
Future versions of GNU Fortran may improve this behavior.
-The default value for @var{n} is 32768.
+The default value for @var{n} is 65536.
@item -fstack-arrays
@opindex @code{fstack-arrays}
diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c
index ef37cccec97..146be2f1420 100644
--- a/gcc/fortran/options.c
+++ b/gcc/fortran/options.c
@@ -437,7 +437,7 @@ gfc_post_options (const char **pfilename)
/* Set default. */
if (flag_max_stack_var_size == -2)
- flag_max_stack_var_size = 32768;
+ flag_max_stack_var_size = 65536;
/* Implement -fno-automatic as -fmax-stack-var-size=0. */
if (!flag_automatic)
diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index 86c3d3a9796..2a9b852568a 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -753,6 +753,16 @@ gfc_finish_var_decl (tree decl, gfc_symbol * sym)
|| sym->attr.allocatable)
&& !DECL_ARTIFICIAL (decl))
{
+ gfc_warning (OPT_Wsurprising,
+ "Array %qs at %L is larger than limit set by"
+ " %<-fmax-stack-var-size=%>, moved from stack to static"
+ " storage. This makes the procedure unsafe when called"
+ " recursively, or concurrently from multiple threads."
+ " Consider using %<-frecursive%>, or increase the"
+ " %<-fmax-stack-var-size=%> limit, or change the code to"
+ " use an ALLOCATABLE array.",
+ sym->name, &sym->declared_at);
+
TREE_STATIC (decl) = 1;
/* Because the size of this variable isn't known until now, we may have
--
2.17.1