On 29 August 2016 at 19:59, Marek Polacek <pola...@redhat.com> wrote:
> On Mon, Aug 29, 2016 at 04:25:25PM +0200, Tobias Burnus wrote:
>> Prathamesh Kulkarni wrote:
>> > Attachment: pr35503-3.txt
>>
>> I tried the patch - and it found a bug in our code; nice!
>>
>>
>> (a) Regarding the [-Werror] output:
>>
>> error: passing argument 24 to restrict qualified parameter aliases with
>> argument 29 [-Werror]
>>
>> Shouldn't that output "[-Werror=restrict]" instead of a bare "[-Werror]?
>> Namely, instead of
>>
>> + warning_at (loc, 0,
>> + "passing argument %u to restrict qualified parameter
>> aliases with "
>> + "argument %u", param_pos + 1, i + 1);
>>
>> I think one gets this with
>> warning_at (loc, OPT_Wrestrict, ...
>
> Yes, this needs to be fixed in the patch.
Hi,
Thanks for all the suggestions, I have tried to incorporate them in
the attached version.
To avoid duplicating the warnings for multiple aliased arguments,
I am using TREE_VISITED to mark all the aliased arguments of the current
arg, which makes diagnostic emitted only once per same set of aliases.
Is using TREE_VISITED ok as in the patch ?
eg:
void f(int *__restrict x, int *y, int *__restrict z, int *w);
void foo(int a, int b)
{
f (&a, &b, &a, &a);
}
Output:
test-2.c: In function ‘foo’:
test-2.c:5:6: warning: passing argument 1 to restrict-qualified
parameter aliases with arguments 3, 4 [-Wrestrict]
f (&a, &b, &a, &a);
^~
Using EXPR_LOCATION (arg), helps underline the argument for both C and C++
as in the example above. However in case of variadic functions, it
appears C++FE doesn't set EXPR_LOCATION,
so I am falling back to using input_location if EXPR_LOCATION is unknown.
However it gives the location correctly for non-variadic functions.
For setting locations correctly I will try the approach suggested by Jason in
https://gcc.gnu.org/ml/gcc-patches/2016-08/msg01987.html
I was wondering how to underline all the aliased arguments ?
I would like to see the output for above eg as:
test-2.c: In function ‘foo’:
test-2.c:5:6: warning: passing argument 1 to restrict-qualified
parameter aliases with arguments 3, 4 [-Wrestrict]
f (&a, &b, &a, &a);
^~ ~~ ~~
I would be grateful for suggestions for the same.
Bootstrap+test in progress on x86_64-unknown-linux-gnu.
Thanks,
Prathamesh
>
> Marek
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 3feb910..abb92b3 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -13057,4 +13057,76 @@ diagnose_mismatched_attributes (tree olddecl, tree
newdecl)
return warned;
}
+/* Warn if an argument at position param_pos is passed to a
+ restrict-qualified param, and it aliases with another argument. */
+
+void
+warn_for_restrict (unsigned param_pos, vec<tree, va_gc> *args)
+{
+ tree arg = (*args)[param_pos];
+ if (TREE_VISITED (arg))
+ return;
+
+ location_t loc = (EXPR_LOCATION (arg) != UNKNOWN_LOCATION)
+ ? EXPR_LOCATION (arg)
+ : input_location;
+
+ if (operand_equal_p (arg, null_pointer_node, 0))
+ return;
+
+ unsigned i;
+ tree current_arg;
+ auto_vec<unsigned> arg_positions;
+
+ FOR_EACH_VEC_ELT (*args, i, current_arg)
+ {
+ if (i == param_pos)
+ continue;
+
+ tree current_arg = (*args)[i];
+ if (operand_equal_p (arg, current_arg, 0))
+ {
+ TREE_VISITED (current_arg) = 1;
+ arg_positions.safe_push (i);
+ }
+ }
+
+ if (arg_positions.is_empty ())
+ return;
+
+ struct obstack fmt_obstack;
+ gcc_obstack_init (&fmt_obstack);
+ char *fmt = (char *) obstack_alloc (&fmt_obstack, 0);
+
+ char num[32];
+ sprintf (num, "%u", param_pos + 1);
+
+ obstack_grow (&fmt_obstack, "passing argument ",
+ strlen ("passing argument "));
+ obstack_grow (&fmt_obstack, num, strlen (num));
+ obstack_grow (&fmt_obstack,
+ " to restrict-qualified parameter aliases with argument",
+ strlen (" to restrict-qualified parameter "
+ "aliases with argument"));
+
+ /* make argument plural and append space. */
+ if (arg_positions.length () > 1)
+ obstack_1grow (&fmt_obstack, 's');
+ obstack_1grow (&fmt_obstack, ' ');
+
+ unsigned pos;
+ FOR_EACH_VEC_ELT (arg_positions, i, pos)
+ {
+ sprintf (num, "%u", pos + 1);
+ obstack_grow (&fmt_obstack, num, strlen (num));
+
+ if (i < arg_positions.length () - 1)
+ obstack_grow (&fmt_obstack, ", ", strlen (", "));
+ }
+
+ obstack_1grow (&fmt_obstack, 0);
+ warning_at (loc, OPT_Wrestrict, fmt);
+ obstack_free (&fmt_obstack, fmt);
+}
+
#include "gt-c-family-c-common.h"
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index bc22baa..cdb762e 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -920,6 +920,7 @@ extern void c_parse_final_cleanups (void);
extern void warn_for_omitted_condop (location_t, tree);
extern void warn_for_memset (location_t, tree, tree, int);
+extern void warn_for_restrict (unsigned, vec<tree, va_gc> *);
/* These macros provide convenient access to the various _STMT nodes. */
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index a5358ed..a029a86 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1012,6 +1012,11 @@ Wduplicate-decl-specifier
C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
Warn when a declaration has duplicate const, volatile, restrict or _Atomic
specifier.
+Wrestrict
+C C++ Var(warn_restrict) Warning LangEnabledBy(C C++,Wall)
+Warn when an argument passed to a restrict-qualified parameter aliases with
+another argument.
+
ansi
C ObjC C++ ObjC++
A synonym for -std=c89 (for C) or -std=c++98 (for C++).
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index fe0c95f..7eaca04 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -8369,6 +8369,24 @@ c_parser_postfix_expression_after_primary (c_parser
*parser,
warn_for_memset (expr_loc, arg0, arg2, literal_zero_mask);
}
+ if (TREE_CODE (expr.value) == FUNCTION_DECL && warn_restrict)
+ {
+ unsigned i;
+ tree arg;
+ FOR_EACH_VEC_ELT (*exprlist, i, arg)
+ TREE_VISITED (arg) = 0;
+
+ unsigned param_pos = 0;
+ function_args_iterator iter;
+ tree t;
+ FOREACH_FUNCTION_ARGS (TREE_TYPE (expr.value), t, iter)
+ {
+ if (POINTER_TYPE_P (t) && TYPE_RESTRICT (t))
+ warn_for_restrict (param_pos, exprlist);
+ param_pos++;
+ }
+ }
+
start = expr.get_start ();
finish = parser->tokens_buf[0].get_finish ();
expr.value
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 690e928..5d0182f 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -6878,6 +6878,25 @@ cp_parser_postfix_expression (cp_parser *parser, bool
address_p, bool cast_p,
warn_for_memset (input_location, arg0, arg2, literal_mask);
}
+ if (TREE_CODE (postfix_expression) == FUNCTION_DECL
+ && warn_restrict)
+ {
+ unsigned i;
+ tree arg;
+ FOR_EACH_VEC_ELT (*args, i, arg)
+ TREE_VISITED (arg) = 0;
+
+ unsigned param_pos = 0;
+ for (tree decl = DECL_ARGUMENTS (postfix_expression);
+ decl != NULL_TREE;
+ decl = DECL_CHAIN (decl), param_pos++)
+ {
+ tree type = TREE_TYPE (decl);
+ if (POINTER_TYPE_P (type) && TYPE_RESTRICT (type))
+ warn_for_restrict (param_pos, args);
+ }
+ }
+
if (TREE_CODE (postfix_expression) == COMPONENT_REF)
{
tree instance = TREE_OPERAND (postfix_expression, 0);
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 1f04501..3bd9612 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -288,7 +288,7 @@ Objective-C and Objective-C++ Dialects}.
-Wparentheses -Wno-pedantic-ms-format @gol
-Wplacement-new -Wplacement-new=@var{n} @gol
-Wpointer-arith -Wno-pointer-to-int-cast @gol
--Wno-pragmas -Wredundant-decls -Wno-return-local-addr @gol
+-Wno-pragmas -Wredundant-decls -Wrestrict -Wno-return-local-addr @gol
-Wreturn-type -Wsequence-point -Wshadow -Wno-shadow-ivar @gol
-Wshift-overflow -Wshift-overflow=@var{n} @gol
-Wshift-count-negative -Wshift-count-overflow -Wshift-negative-value @gol
@@ -5274,6 +5274,12 @@ compilations.
Warn when deleting a pointer to incomplete type, which may cause
undefined behavior at runtime. This warning is enabled by default.
+@item -Wrestrict @r{(C and C++ only)}
+@opindex Wrestrict
+@opindex Wno-restrict
+Warn when an argument passed to a restrict-qualified parameter
+aliases with another argument
+
@item -Wuseless-cast @r{(C++ and Objective-C++ only)}
@opindex Wuseless-cast
@opindex Wno-useless-cast
diff --git a/gcc/testsuite/c-c++-common/pr35503-1.c
b/gcc/testsuite/c-c++-common/pr35503-1.c
new file mode 100644
index 0000000..b47fdda
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr35503-1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-Wrestrict" } */
+
+int foo (const char *__restrict buf, const char *__restrict fmt, ...);
+
+void f(void)
+{
+ char buf[100] = "hello";
+ foo (buf, "%s-%s", buf, "world"); /* { dg-warning "passing argument 1 to
restrict-qualified parameter aliases with argument 3" } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr35503-2.c
b/gcc/testsuite/c-c++-common/pr35503-2.c
new file mode 100644
index 0000000..c7828b8
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr35503-2.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-Wrestrict" } */
+
+void f(int *__restrict x, int *__restrict y);
+
+void foo(int a)
+{
+ f (&a, &a); /* { dg-warning "passing argument 1 to restrict-qualified
parameter aliases with argument 2" } */
+}
diff --git a/gcc/testsuite/c-c++-common/pr35503-3.c
b/gcc/testsuite/c-c++-common/pr35503-3.c
new file mode 100644
index 0000000..8cbacab
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr35503-3.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-Wrestrict" } */
+
+void f(int *x, int *__restrict y);
+
+void foo(int a)
+{
+ f (&a, &a); /* { dg-warning "passing argument 2 to restrict-qualified
parameter aliases with argument 1" } */
+}
