* [C] Issue an error on scalar va_list with reverse storage order
@ 2015-12-03 14:54 Eric Botcazou
2015-12-03 23:29 ` Joseph Myers
2015-12-08 15:34 ` Matthew Wahab
0 siblings, 2 replies; 4+ messages in thread
From: Eric Botcazou @ 2015-12-03 14:54 UTC (permalink / raw)
To: gcc-patches
[-- Attachment #1: Type: text/plain, Size: 965 bytes --]
Hi,
further testing revealed an issue with va_arg handling and reverse scalar
storage order on some platforms: when va_list is scalar, passing a field of a
structure with reverse SSO as first argument to va_start/va_arg/va_end doesn't
work because the machinery takes its address and this is not allowed for such
a field (it's really a corner case but gcc.c-torture/execute/stdarg-2.c does
exercise it). Hence the attached patch which issues an error in this case.
Tested on x86_64-suse-linux, OK for the mainline?
2015-12-03 Eric Botcazou <ebotcazou@adacore.com>
* c-tree.h (c_build_va_arg): Adjust prototype.
* c-parser.c (c_parser_postfix_expression): Adjust call to above.
* c-typeck.c (c_build_va_arg): Rename LOC parameter to LOC2, add LOC1
parameter, adjust throughout and issue an error if EXPR is a component
with reverse storage order.
2015-12-03 Eric Botcazou <ebotcazou@adacore.com>
* gcc.dg/sso-9.c: New test.
--
Eric Botcazou
[-- Attachment #2: sso_va_arg.diff --]
[-- Type: text/x-patch, Size: 2553 bytes --]
Index: c-parser.c
===================================================================
--- c-parser.c (revision 231206)
+++ c-parser.c (working copy)
@@ -7485,7 +7485,7 @@ c_parser_postfix_expression (c_parser *p
else
{
tree type_expr = NULL_TREE;
- expr.value = c_build_va_arg (loc, e1.value,
+ expr.value = c_build_va_arg (start_loc, e1.value, loc,
groktypename (t1, &type_expr, NULL));
if (type_expr)
{
Index: c-tree.h
===================================================================
--- c-tree.h (revision 231206)
+++ c-tree.h (working copy)
@@ -661,7 +661,7 @@ extern tree c_finish_omp_task (location_
extern void c_finish_omp_cancel (location_t, tree);
extern void c_finish_omp_cancellation_point (location_t, tree);
extern tree c_finish_omp_clauses (tree, bool, bool = false);
-extern tree c_build_va_arg (location_t, tree, tree);
+extern tree c_build_va_arg (location_t, tree, location_t, tree);
extern tree c_finish_transaction (location_t, tree, int);
extern bool c_tree_equal (tree, tree);
extern tree c_build_function_call_vec (location_t, vec<location_t>, tree,
Index: c-typeck.c
===================================================================
--- c-typeck.c (revision 231206)
+++ c-typeck.c (working copy)
@@ -13426,20 +13426,28 @@ c_build_qualified_type (tree type, int t
/* Build a VA_ARG_EXPR for the C parser. */
tree
-c_build_va_arg (location_t loc, tree expr, tree type)
+c_build_va_arg (location_t loc1, tree expr, location_t loc2, tree type)
{
if (error_operand_p (type))
return error_mark_node;
+ /* VA_ARG_EXPR cannot be used for a scalar va_list with reverse storage
+ order because it takes the address of the expression. */
+ else if (handled_component_p (expr)
+ && reverse_storage_order_for_component_p (expr))
+ {
+ error_at (loc1, "cannot use %<va_arg%> with reverse storage order");
+ return error_mark_node;
+ }
else if (!COMPLETE_TYPE_P (type))
{
- error_at (loc, "second argument to %<va_arg%> is of incomplete "
+ error_at (loc2, "second argument to %<va_arg%> is of incomplete "
"type %qT", type);
return error_mark_node;
}
else if (warn_cxx_compat && TREE_CODE (type) == ENUMERAL_TYPE)
- warning_at (loc, OPT_Wc___compat,
+ warning_at (loc2, OPT_Wc___compat,
"C++ requires promoted type, not enum type, in %<va_arg%>");
- return build_va_arg (loc, expr, type);
+ return build_va_arg (loc2, expr, type);
}
/* Return truthvalue of whether T1 is the same tree structure as T2.
[-- Attachment #3: sso-9.c --]
[-- Type: text/x-csrc, Size: 502 bytes --]
/* Test support of scalar_storage_order attribute */
/* { dg-do compile } */
#include <stdarg.h>
int x;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
struct __attribute__((scalar_storage_order("big-endian"))) Rec
{
va_list v;
};
#else
struct __attribute__((scalar_storage_order("little-endian"))) Rec
{
va_list v;
};
#endif
void foo (int i, ...)
{
struct Rec a;
va_start (a.v, i);
a.v = a.v, x = va_arg (a.v, int); /* { dg-error "array type|reverse storage order" } */
va_end (a.v);
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [C] Issue an error on scalar va_list with reverse storage order
2015-12-03 14:54 [C] Issue an error on scalar va_list with reverse storage order Eric Botcazou
@ 2015-12-03 23:29 ` Joseph Myers
2015-12-08 15:34 ` Matthew Wahab
1 sibling, 0 replies; 4+ messages in thread
From: Joseph Myers @ 2015-12-03 23:29 UTC (permalink / raw)
To: Eric Botcazou; +Cc: gcc-patches
On Thu, 3 Dec 2015, Eric Botcazou wrote:
> Hi,
>
> further testing revealed an issue with va_arg handling and reverse scalar
> storage order on some platforms: when va_list is scalar, passing a field of a
> structure with reverse SSO as first argument to va_start/va_arg/va_end doesn't
> work because the machinery takes its address and this is not allowed for such
> a field (it's really a corner case but gcc.c-torture/execute/stdarg-2.c does
> exercise it). Hence the attached patch which issues an error in this case.
>
> Tested on x86_64-suse-linux, OK for the mainline?
OK.
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [C] Issue an error on scalar va_list with reverse storage order
2015-12-03 14:54 [C] Issue an error on scalar va_list with reverse storage order Eric Botcazou
2015-12-03 23:29 ` Joseph Myers
@ 2015-12-08 15:34 ` Matthew Wahab
2015-12-08 17:09 ` Eric Botcazou
1 sibling, 1 reply; 4+ messages in thread
From: Matthew Wahab @ 2015-12-08 15:34 UTC (permalink / raw)
To: Eric Botcazou, gcc-patches
Hello
On 03/12/15 14:53, Eric Botcazou wrote:
> further testing revealed an issue with va_arg handling and reverse scalar storage
> order on some platforms: when va_list is scalar, passing a field of a structure
> with reverse SSO as first argument to va_start/va_arg/va_end doesn't work because
> the machinery takes its address and this is not allowed for such a field (it's
> really a corner case but gcc.c-torture/execute/stdarg-2.c does exercise it). Hence
> the attached patch which issues an error in this case.
The new gcc.dg/sso-9.c test is failing for aarch64 and arm targets. There's no error
generated if I compile the test from the command line for aarch64-none-elf. GCC for
x86_64 does generate the error.
Matthew
> 2015-12-03 Eric Botcazou <ebotcazou@adacore.com>
>
> * c-tree.h (c_build_va_arg): Adjust prototype. * c-parser.c
> (c_parser_postfix_expression): Adjust call to above. * c-typeck.c
> (c_build_va_arg): Rename LOC parameter to LOC2, add LOC1 parameter, adjust
> throughout and issue an error if EXPR is a component with reverse storage order.
>
>
> 2015-12-03 Eric Botcazou <ebotcazou@adacore.com>
>
> * gcc.dg/sso-9.c: New test.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [C] Issue an error on scalar va_list with reverse storage order
2015-12-08 15:34 ` Matthew Wahab
@ 2015-12-08 17:09 ` Eric Botcazou
0 siblings, 0 replies; 4+ messages in thread
From: Eric Botcazou @ 2015-12-08 17:09 UTC (permalink / raw)
To: Matthew Wahab; +Cc: gcc-patches
[-- Attachment #1: Type: text/plain, Size: 330 bytes --]
> The new gcc.dg/sso-9.c test is failing for aarch64 and arm targets. There's
> no error generated if I compile the test from the command line for
> aarch64-none-elf. GCC for x86_64 does generate the error.
Fixed like so, applied as obvious, thanks for the heads up.
* gcc.dg/sso-9.c (foo): Robustify trick.
--
Eric Botcazou
[-- Attachment #2: p.diff --]
[-- Type: text/x-patch, Size: 437 bytes --]
Index: gcc.dg/sso-9.c
===================================================================
--- gcc.dg/sso-9.c (revision 231394)
+++ gcc.dg/sso-9.c (working copy)
@@ -22,6 +22,6 @@ void foo (int i, ...)
{
struct Rec a;
va_start (a.v, i);
- a.v = a.v, x = va_arg (a.v, int); /* { dg-error "array type|reverse storage order" } */
+ a.v = 0, x = va_arg (a.v, int); /* { dg-error "type|reverse storage order" } */
va_end (a.v);
}
^ permalink raw reply [flat|nested] 4+ messages in thread
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2015-12-03 14:54 [C] Issue an error on scalar va_list with reverse storage order Eric Botcazou
2015-12-03 23:29 ` Joseph Myers
2015-12-08 15:34 ` Matthew Wahab
2015-12-08 17:09 ` Eric Botcazou
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