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[v2 of PATCH 13/14] c-format.c: handle location wrappers
- From: David Malcolm <dmalcolm at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>
- Cc: Nathan Sidwell <nathan at acm dot org>, Jakub Jelinek <jakub at redhat dot com>, Richard Biener <richard dot guenther at gmail dot com>, gcc-patches List <gcc-patches at gcc dot gnu dot org>, David Malcolm <dmalcolm at redhat dot com>
- Date: Sun, 17 Dec 2017 11:29:43 -0500
- Subject: [v2 of PATCH 13/14] c-format.c: handle location wrappers
- Authentication-results: sourceware.org; auth=none
- References: <479bff3c-baaa-26c0-c7b4-c5c69cee2d32@redhat.com>
On Mon, 2017-12-11 at 18:45 -0500, Jason Merrill wrote:
> On 11/10/2017 04:45 PM, David Malcolm wrote:
> > gcc/c-family/ChangeLog:
> > * c-format.c (check_format_arg): Strip any location wrapper
> > around
> > format_tree.
> > ---
> > gcc/c-family/c-format.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
> > index 164d035..6b436ec 100644
> > --- a/gcc/c-family/c-format.c
> > +++ b/gcc/c-family/c-format.c
> > @@ -1536,6 +1536,8 @@ check_format_arg (void *ctx, tree
> > format_tree,
> >
> > location_t fmt_param_loc = EXPR_LOC_OR_LOC (format_tree,
> > input_location);
> >
> > + STRIP_ANY_LOCATION_WRAPPER (format_tree);
> > +
> > if (VAR_P (format_tree))
> > {
> > /* Pull out a constant value if the front end didn't. */
>
> It seems like we want fold_for_warn here instead of the special
> variable
> handling. That probably makes sense for the other places you change
> in
> this patch, too.
>
> Jason
Here's an updated version of the patch which uses fold_for_warn,
rather than STRIP_ANY_LOCATION_WRAPPER.
In one place it was necessary to add a STRIP_NOPS, since the
fold_for_warn can add a cast around a:
ADDR_EXPR <POINTER_TYPE(ARRAY_TYPE(char))> (
STRING_CST)
turning it into a:
NOP_EXPR<POINTER_TYPE(char))> (
ADDR_EXPR <POINTER_TYPE(ARRAY_TYPE(char))> (
STRING_CST))
which without a STRIP_NOPS leads to a bail-out here:
1596 if (TREE_CODE (format_tree) != ADDR_EXPR)
1597 {
1598 res->number_non_literal++;
1599 return;
1600 }
and thus -Wformat-security not recognizing string literals.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu, as
part of the kit.
Is this OK for trunk, assuming the rest of the kit is approved?
gcc/c-family/ChangeLog:
* c-format.c (check_format_arg): Strip any location wrapper around
format_tree.
---
gcc/c-family/c-format.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
index 164d035..47aca55 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -1536,6 +1536,8 @@ check_format_arg (void *ctx, tree format_tree,
location_t fmt_param_loc = EXPR_LOC_OR_LOC (format_tree, input_location);
+ format_tree = fold_for_warn (format_tree);
+
if (VAR_P (format_tree))
{
/* Pull out a constant value if the front end didn't. */
@@ -1591,13 +1593,14 @@ check_format_arg (void *ctx, tree format_tree,
}
offset = int_cst_value (arg1);
}
+ STRIP_NOPS (format_tree);
if (TREE_CODE (format_tree) != ADDR_EXPR)
{
res->number_non_literal++;
return;
}
res->format_string_loc = EXPR_LOC_OR_LOC (format_tree, input_location);
- format_tree = TREE_OPERAND (format_tree, 0);
+ format_tree = fold_for_warn (TREE_OPERAND (format_tree, 0));
if (format_types[info->format_type].flags
& (int) FMT_FLAG_PARSE_ARG_CONVERT_EXTERNAL)
{
@@ -1634,7 +1637,9 @@ check_format_arg (void *ctx, tree format_tree,
if (TREE_CODE (format_tree) == ARRAY_REF
&& tree_fits_shwi_p (TREE_OPERAND (format_tree, 1))
&& (offset += tree_to_shwi (TREE_OPERAND (format_tree, 1))) >= 0)
- format_tree = TREE_OPERAND (format_tree, 0);
+ {
+ format_tree = fold_for_warn (TREE_OPERAND (format_tree, 0));
+ }
if (offset < 0)
{
res->number_non_literal++;
--
1.8.5.3