diff mbox

PR35503 - warn for restrict pointer

Message ID CAAgBjMniry2QSMzoVc5TVDsXgizoQ0RK-U=xGM1hPwYeWzTDGg@mail.gmail.com
State Superseded
Headers show

Commit Message

Prathamesh Kulkarni Sept. 20, 2016, 12:09 p.m. UTC
On 20 September 2016 at 08:57, Martin Sebor <msebor@gmail.com> wrote:
>> and used

>> pp_format for formatting arg_positions by adding specifier %I (name

>> chosen arbitrarily).

>> Does that look OK ?

>

>

> diff --git a/gcc/pretty-print.c b/gcc/pretty-print.c

> index a39815e..e8bd1ef 100644

> --- a/gcc/pretty-print.c

> +++ b/gcc/pretty-print.c

> @@ -610,6 +610,23 @@ pp_format (pretty_printer *pp, text_info *text)

>               (pp, *text->args_ptr, precision, unsigned, "u");

>           break;

>

> +       case 'I':

>

> The comment just above pp_format that lists the format specifiers

> understood by the function should be updated.  There probably (I

> hope) is more formal documentation of the format specifiers

> somewhere else that should be updated as well.

>

> That said, since this specifier formats a vec<int>, it seems that

> it might be useful to be able to format vectors of other elements,

> such as short and long.  With that in mind, would adding a new V

> length modifier instead be a more regular way to extend the pretty

> printer to these types?  The V length modifier would have to be

> accepted in conjunction with other length modifiers (h, l, etc

> and type specifiers (d, i, o, etc.).  E.g, "%hVu" would accept

> a vec<unsigned short>*  as an argument and format it as a sequence

> of decimal numbers, and "%lVx" would do the same for vec<long>*

> formatting them in hex.

Hi,
Thanks everyone for the suggestions.

This patch does the following:
a) adds warning_at_rich_loc_n(). Somehow I missed David's clear explanation of
warning_at_rich_loc_n earlier :(

b) clears TREE_VISITED flag in C/C++ FE after we are done with
warn_for_restrict().
I assumed that TREE_VISITED would be treated as a "scratch" flag and any pass
wishing to use it must set it first, so didn't bother clearing at first.

c) It appears '%I' is already used for some format specifier in
c-family/c-format.c ?
I changed name to %Z instead. Martin suggested a better idea above to
implement %Z as a length modifier so we can extend it to print vec of other
types, like %hZx would print vec<short> formatted in hex.
I am not sure though if it would be a simple fix, and left it as a FIXME
in the patch adding %Z just to print vec<int>, maybe we could revisit it later ?
Could someone please take a look at the change to c-format.c, I am not sure
if I have added that correctly.

Thanks,
Prathamesh
>

> Martin

>
diff mbox

Patch

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index fc25686..742f06d 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -47,6 +47,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "gimplify.h"
 #include "substring-locations.h"
 #include "spellcheck.h"
+#include "gcc-rich-location.h"
 
 cpp_reader *parse_in;		/* Declared in c-pragma.h.  */
 
@@ -13084,4 +13085,53 @@  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) || operand_equal_p (arg, null_pointer_node, 0))
+    return;
+
+  location_t loc = EXPR_LOC_OR_LOC (arg, input_location);
+  gcc_rich_location richloc (loc);
+
+  unsigned i;
+  tree current_arg;
+  auto_vec<int> 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 + 1); 
+	}
+    }
+
+  if (arg_positions.is_empty ())
+    return;
+
+  int pos;
+  FOR_EACH_VEC_ELT (arg_positions, i, pos)
+    {
+      tree arg = (*args)[pos - 1];
+      if (EXPR_HAS_LOCATION (arg))
+	richloc.add_range (EXPR_LOCATION (arg), false);
+    }
+
+  warning_at_rich_loc_n (&richloc, OPT_Wrestrict, arg_positions.length (),
+			 "passing argument %i to restrict-qualified parameter"
+			 " aliases with argument %Z",
+			 "passing argument %i to restrict-qualified parameter"
+			 " aliases with arguments %Z",
+			 param_pos + 1, &arg_positions); 
+}
+
 #include "gt-c-family-c-common.h"
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 5bbf951..f29ea1f 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -922,6 +922,7 @@  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-format.c b/gcc/c-family/c-format.c
index bf39ee0..b27d34f 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -713,6 +713,7 @@  static const format_char_info gcc_tdiag_char_table[] =
   { "r",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "cR",   NULL },
   { "<>'R",0, STD_C89, NOARGUMENTS, "",      "",   NULL },
   { "m",   0, STD_C89, NOARGUMENTS, "q",     "",   NULL },
+  { "Z",   1, STD_C89, { T89_C,   BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN,  BADLEN  }, "",    "",   NULL },
   { NULL,  0, STD_C89, NOLENGTHS, NULL, NULL, NULL }
 };
 
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index c55c7c3..08edea0 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -1032,6 +1032,11 @@  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 ObjC C++ ObjC++ Var(warn_restrict) Warning LangEnabledBy(C ObjC C++ ObjC++,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 58424a9..3ad1f67 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -8368,6 +8368,28 @@  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_SAFE_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)
+		      && !TYPE_READONLY (TREE_TYPE (t)))
+		    warn_for_restrict (param_pos, exprlist);
+		  param_pos++;
+		}
+
+	      FOR_EACH_VEC_SAFE_ELT (exprlist, i, arg)
+		TREE_VISITED (arg) = 0;
+	    }
+
 	  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 fb88021..58fc615 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -6878,6 +6878,29 @@  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_SAFE_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)
+			&& !TYPE_READONLY (TREE_TYPE (type)))
+		      warn_for_restrict (param_pos, args);
+		  }
+
+		FOR_EACH_VEC_SAFE_ELT (args, i, arg)
+		  TREE_VISITED (arg) = 0;
+	      }
+
 	    if (TREE_CODE (postfix_expression) == COMPONENT_REF)
 	      {
 		tree instance = TREE_OPERAND (postfix_expression, 0);
diff --git a/gcc/diagnostic-core.h b/gcc/diagnostic-core.h
index 51df150..4a1766c 100644
--- a/gcc/diagnostic-core.h
+++ b/gcc/diagnostic-core.h
@@ -65,6 +65,9 @@  extern bool warning_at (location_t, int, const char *, ...)
     ATTRIBUTE_GCC_DIAG(3,4);
 extern bool warning_at_rich_loc (rich_location *, int, const char *, ...)
     ATTRIBUTE_GCC_DIAG(3,4);
+extern bool warning_at_rich_loc_n (rich_location *, int, int, const char *,
+				  const char *, ...)
+    ATTRIBUTE_GCC_DIAG(4, 6) ATTRIBUTE_GCC_DIAG(5, 6);
 extern void error (const char *, ...) ATTRIBUTE_GCC_DIAG(1,2);
 extern void error_n (location_t, int, const char *, const char *, ...)
     ATTRIBUTE_GCC_DIAG(3,5) ATTRIBUTE_GCC_DIAG(4,5);
diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
index 585028e..167a1b5 100644
--- a/gcc/diagnostic.c
+++ b/gcc/diagnostic.c
@@ -53,6 +53,10 @@  static bool diagnostic_impl (rich_location *, int, const char *,
 static bool diagnostic_n_impl (location_t, int, int, const char *,
 			       const char *, va_list *,
 			       diagnostic_t) ATTRIBUTE_GCC_DIAG(5,0);
+static bool diagnostic_n_impl_richloc (rich_location *, int, int, const char *,
+				       const char *, va_list *,
+				       diagnostic_t) ATTRIBUTE_GCC_DIAG(5,0);
+
 static void error_recursion (diagnostic_context *) ATTRIBUTE_NORETURN;
 static void real_abort (void) ATTRIBUTE_NORETURN;
 
@@ -1064,6 +1068,22 @@  diagnostic_impl (rich_location *richloc, int opt,
   return report_diagnostic (&diagnostic);
 }
 
+/* Same as diagonostic_n_impl taking rich_location instead of location_t.  */
+static bool
+diagnostic_n_impl_richloc (rich_location *richloc, int opt, int n,
+			   const char *singular_gmsgid,
+			   const char *plural_gmsgid,
+			   va_list *ap, diagnostic_t kind)
+{
+  diagnostic_info diagnostic;
+  diagnostic_set_info_translated (&diagnostic,
+                                  ngettext (singular_gmsgid, plural_gmsgid, n),
+                                  ap, richloc, kind);
+  if (kind == DK_WARNING)
+    diagnostic.option_index = opt;
+  return report_diagnostic (&diagnostic);
+} 
+
 /* Implement inform_n, warning_n, and error_n, as documented and
    defined below.  */
 static bool
@@ -1072,14 +1092,9 @@  diagnostic_n_impl (location_t location, int opt, int n,
 		   const char *plural_gmsgid,
 		   va_list *ap, diagnostic_t kind)
 {
-  diagnostic_info diagnostic;
   rich_location richloc (line_table, location);
-  diagnostic_set_info_translated (&diagnostic,
-                                  ngettext (singular_gmsgid, plural_gmsgid, n),
-                                  ap, &richloc, kind);
-  if (kind == DK_WARNING)
-    diagnostic.option_index = opt;
-  return report_diagnostic (&diagnostic);
+  return diagnostic_n_impl_richloc (&richloc, opt, n,
+				    singular_gmsgid, plural_gmsgid, ap, kind);
 }
 
 bool
@@ -1170,6 +1185,21 @@  warning_at_rich_loc (rich_location *richloc, int opt, const char *gmsgid, ...)
   return ret;
 }
 
+/* Same as warning_at_rich_loc but for plural variant.  */
+
+bool
+warning_at_rich_loc_n (rich_location *richloc, int opt, int n,
+		       const char *singular_gmsgid, const char *plural_gmsgid, ...)
+{
+  va_list ap;
+  va_start (ap, plural_gmsgid);
+  bool ret = diagnostic_n_impl_richloc (richloc, opt, n,
+					singular_gmsgid, plural_gmsgid,
+					&ap, DK_WARNING);
+  va_end (ap);
+  return ret;
+}
+
 /* A warning at LOCATION.  Use this for code which is correct according to the
    relevant language specification but is likely to be buggy anyway.
    Returns true if the warning was printed, false if it was inhibited.  */
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8eb5eff..d24eb6f 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
@@ -5348,6 +5348,12 @@  compilations.
 Warn when deleting a pointer to incomplete type, which may cause
 undefined behavior at runtime.  This warning is enabled by default.
 
+@item -Wrestrict
+@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/pretty-print.c b/gcc/pretty-print.c
index a39815e..20e697d 100644
--- a/gcc/pretty-print.c
+++ b/gcc/pretty-print.c
@@ -295,6 +295,11 @@  pp_indent (pretty_printer *pp)
    %Ns: likewise, but length specified as constant in the format string.
    Flag 'q': quote formatted text (must come immediately after '%').
 
+   FIXME: It would be a better idea to add %Z as a length modifier to print
+   vec of other types. For instance %hZx would print vec<short> in hex format.
+   Currently %Z just prints vec<int> formatted in decimal.
+   %Z: vec<int>.
+
    Arguments can be used sequentially, or through %N$ resp. *N$
    notation Nth argument after the format string.  If %N$ / *N$
    notation is used, it must be used for all arguments, except %m, %%,
@@ -610,6 +615,23 @@  pp_format (pretty_printer *pp, text_info *text)
 	      (pp, *text->args_ptr, precision, unsigned, "u");
 	  break;
 
+	case 'Z':
+	  {
+	    vec<int> *v = va_arg (*text->args_ptr, vec<int> *);
+	    unsigned i;
+	    int pos;
+
+	    FOR_EACH_VEC_ELT ((*v), i, pos)
+	      {
+		pp_scalar (pp, "%i", pos);
+		if (i < v->length () - 1)
+		  {
+		    pp_comma (pp);
+		    pp_space (pp);
+		  }
+	      }
+	    break;
+	 }
 	case 'x':
 	  if (wide)
 	    pp_scalar (pp, HOST_WIDE_INT_PRINT_HEX,
@@ -1424,6 +1446,17 @@  test_pp_format ()
 			    "`\33[01m\33[Kfoo\33[m\33[K' 12345678", "%qs %x",
 			    "foo", 0x12345678);
 
+  /* Verify %Z.  */
+  auto_vec<int> v;
+  v.safe_push (1);
+  v.safe_push (2);
+  v.safe_push (3);
+  ASSERT_PP_FORMAT_2 ("1, 2, 3 12345678", "%Z %x", &v, 0x12345678);
+
+  auto_vec<int> v2;
+  v2.safe_push (0);
+  ASSERT_PP_FORMAT_2 ("0 12345678", "%Z %x", &v2, 0x12345678);
+
   /* Verify that combinations work, along with unformatted text.  */
   assert_pp_format (SELFTEST_LOCATION,
 		    "the quick brown fox jumps over the lazy dog",
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..25e3721
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr35503-1.c
@@ -0,0 +1,10 @@ 
+/* { dg-do compile } */
+/* { dg-options "-Wrestrict" } */
+
+int foo (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..bfcd944
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr35503-2.c
@@ -0,0 +1,14 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fdiagnostics-show-caret -Wrestrict" } */
+
+void f(int *__restrict x, int *y, int *__restrict z, int *w);
+
+void foo(int alpha, int beta)
+{
+  f (&alpha, &beta, &alpha, &alpha); /* { dg-warning "passing argument 1 to restrict-qualified parameter aliases with arguments 3, 4" } */
+
+/* { dg-begin-multiline-output "" }
+   f (&alpha, &beta, &alpha, &alpha);
+      ^~~~~~         ~~~~~~  ~~~~~~
+   { dg-end-multiline-output "" } */
+}
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" } */
+}