From e9b9fa4cdaedd40ab429c0c98e8801ae039a33e9 Mon Sep 17 00:00:00 2001
From: Martin Sebor <msebor@redhat.com>
Date: Mon, 12 Mar 2018 18:04:16 +0000
Subject: PR tree-optimization/83456 - -Wrestrict false positive on a
 non-overlapping memcpy in an inline function

gcc/ChangeLog:

	PR tree-optimization/83456
	* gimple-fold.c (gimple_fold_builtin_memory_op): Avoid warning
	for perfectly overlapping calls to memcpy.
	(gimple_fold_builtin_memory_chk): Same.
	(gimple_fold_builtin_strcpy): Handle no-warning.
	(gimple_fold_builtin_stxcpy_chk): Same.
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Handle no-warning.

gcc/c-family/ChangeLog:

	PR tree-optimization/83456
	* gcc/c-family/c-common.c (check_function_restrict): Return bool.
	Restore checking of bounded built-in functions.
	(check_function_arguments): Also return the result
	of warn_for_restrict.
	* gcc/c-family/c-common.c (check_function_restrict): Return bool.
	* gcc/c-family/c-warn.c (warn_for_restrict): Return bool.

gcc/testsuite/ChangeLog:

	PR tree-optimization/83456
	* c-c++-common/Wrestrict-2.c: Remove test cases.
	* c-c++-common/Wrestrict.c: Same.
	* gcc.dg/Wrestrict-12.c: New test.
	* gcc.dg/Wrestrict-14.c: New test.

From-SVN: r258455
---
 gcc/c-family/c-common.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

(limited to 'gcc/c-family/c-common.c')

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 858ed68..e1df1d3 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -5309,10 +5309,11 @@ check_function_sentinel (const_tree fntype, int nargs, tree *argarray)
     }
 }
 
-/* Check that the same argument isn't passed to restrict arguments
-   and other arguments.  */
+/* Check that the same argument isn't passed to two or more
+   restrict-qualified formal and issue a -Wrestrict warning
+   if it is.  Return true if a warning has been issued.  */
 
-static void
+static bool
 check_function_restrict (const_tree fndecl, const_tree fntype,
 			 int nargs, tree *argarray)
 {
@@ -5322,11 +5323,14 @@ check_function_restrict (const_tree fndecl, const_tree fntype,
   if (fndecl
       && TREE_CODE (fndecl) == FUNCTION_DECL)
     {
-      /* Skip checking built-ins here.  They are checked in more
-	 detail elsewhere.  */
+      /* Avoid diagnosing calls built-ins with a zero size/bound
+	 here.  They are checked in more detail elsewhere.  */
       if (DECL_BUILT_IN (fndecl)
-	  && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
-	return;
+	  && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
+	  && nargs == 3
+	  && TREE_CODE (argarray[2]) == INTEGER_CST
+	  && integer_zerop (argarray[2]))
+	return false;
 
       if (DECL_ARGUMENTS (fndecl))
 	parms = DECL_ARGUMENTS (fndecl);
@@ -5335,6 +5339,8 @@ check_function_restrict (const_tree fndecl, const_tree fntype,
   for (i = 0; i < nargs; i++)
     TREE_VISITED (argarray[i]) = 0;
 
+  bool warned = false;
+
   for (i = 0; i < nargs && parms && parms != void_list_node; i++)
     {
       tree type;
@@ -5351,11 +5357,13 @@ check_function_restrict (const_tree fndecl, const_tree fntype,
       if (POINTER_TYPE_P (type)
 	  && TYPE_RESTRICT (type)
 	  && !TYPE_READONLY (TREE_TYPE (type)))
-	warn_for_restrict (i, argarray, nargs);
+	warned |= warn_for_restrict (i, argarray, nargs);
     }
 
   for (i = 0; i < nargs; i++)
     TREE_VISITED (argarray[i]) = 0;
+
+  return warned;
 }
 
 /* Helper for check_function_nonnull; given a list of operands which
@@ -5596,8 +5604,10 @@ attribute_fallthrough_p (tree attr)
 
 
 /* Check for valid arguments being passed to a function with FNTYPE.
-   There are NARGS arguments in the array ARGARRAY.  LOC should be used for
-   diagnostics.  Return true if -Wnonnull warning has been diagnosed.  */
+   There are NARGS arguments in the array ARGARRAY.  LOC should be used
+   for diagnostics.  Return true if either -Wnonnull or -Wrestrict has
+   been issued.  */
+
 bool
 check_function_arguments (location_t loc, const_tree fndecl, const_tree fntype,
 			  int nargs, tree *argarray, vec<location_t> *arglocs)
@@ -5620,7 +5630,7 @@ check_function_arguments (location_t loc, const_tree fndecl, const_tree fntype,
     check_function_sentinel (fntype, nargs, argarray);
 
   if (warn_restrict)
-    check_function_restrict (fndecl, fntype, nargs, argarray);
+    warned_p |= check_function_restrict (fndecl, fntype, nargs, argarray);
   return warned_p;
 }
 
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