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PR tree-optimization/84480 - bogus -Wstringop-truncation despite assignment with an inlined string literal

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gcc/ChangeLog:

	PR tree-optimization/84480
	* gimple-fold.c (gimple_fold_builtin_strcpy): Move warnings
	to maybe_diag_stxncpy_trunc.  Call it.
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Integrate warnings
	from gimple_fold_builtin_strcpy.  Print inlining stack.
	(handle_builtin_stxncpy): Print inlining stack.
	* tree-ssa-strlen.h (maybe_diag_stxncpy_trunc): Declare.

gcc/testsuite/ChangeLog:

	PR tree-optimization/84480
	* c-c++-common/Wstringop-truncation.c: Adjust text of expected warnings.
	* g++.dg/warn/Wstringop-truncation-1.C: New test.

From-SVN: r257910
This commit is contained in:
Martin Sebor 2018-02-22 17:35:29 +00:00 • committed by Martin Sebor
parent 73b8b82295
commit 5d0d5d6876
7 changed files with 220 additions and 62 deletions
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10
gcc/ChangeLog
View file

@ -1,3 +1,13 @@
2018-02-22 Martin Sebor <msebor@redhat.com>
PR tree-optimization/84480
* gimple-fold.c (gimple_fold_builtin_strcpy): Move warnings
to maybe_diag_stxncpy_trunc. Call it.
* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Integrate warnings
from gimple_fold_builtin_strcpy. Print inlining stack.
(handle_builtin_stxncpy): Print inlining stack.
* tree-ssa-strlen.h (maybe_diag_stxncpy_trunc): Declare.
2018-02-22 H.J. Lu <hongjiu.lu@intel.com>
PR target/84176

34
gcc/gimple-fold.c
View file

@ -65,6 +65,7 @@ along with GCC; see the file COPYING3. If not see
#include "intl.h"
#include "calls.h"
#include "tree-vector-builder.h"
#include "tree-ssa-strlen.h"
/* Return true when DECL can be referenced from current unit.
FROM_DECL (if non-null) specify constructor of variable DECL was taken from.
@ -1710,37 +1711,8 @@ gimple_fold_builtin_strncpy (gimple_stmt_iterator *gsi,
if (tree_int_cst_lt (ssize, len))
return false;
if (!nonstring)
{
if (tree_int_cst_lt (len, slen))
{
tree fndecl = gimple_call_fndecl (stmt);
gcall *call = as_a <gcall *> (stmt);
warning_at (loc, OPT_Wstringop_truncation,
(tree_int_cst_equal (size_one_node, len)
? G_("%G%qD output truncated copying %E byte "
"from a string of length %E")
: G_("%G%qD output truncated copying %E bytes "
"from a string of length %E")),
call, fndecl, len, slen);
}
else if (tree_int_cst_equal (len, slen))
{
tree fndecl = gimple_call_fndecl (stmt);
gcall *call = as_a <gcall *> (stmt);
warning_at (loc, OPT_Wstringop_truncation,
(tree_int_cst_equal (size_one_node, len)
? G_("%G%qD output truncated before terminating nul "
"copying %E byte from a string of the same "
"length")
: G_("%G%qD output truncated before terminating nul "
"copying %E bytes from a string of the same "
"length")),
call, fndecl, len);
}
}
/* Diagnose truncation that leaves the copy unterminated. */
maybe_diag_stxncpy_trunc (*gsi, src, len);
/* OK transform into builtin memcpy. */
tree fn = builtin_decl_implicit (BUILT_IN_MEMCPY);

6
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,9 @@
2018-02-22 Martin Sebor <msebor@redhat.com>
PR tree-optimization/84480
* c-c++-common/Wstringop-truncation.c: Adjust text of expected warnings.
* g++.dg/warn/Wstringop-truncation-1.C: New test.
2018-02-22 H.J. Lu <hongjiu.lu@intel.com>
PR target/84176

6
gcc/testsuite/c-c++-common/Wstringop-truncation.c
View file

@ -188,7 +188,7 @@ void test_strncpy_ptr (char *d, const char* s, const char *t, int i)
CPY (d, CHOOSE (s, t), 2);
CPY (d, CHOOSE ("", "123"), 1); /* { dg-warning ".strncpy\[^\n\r\]* output may be truncated copying 1 byte from a string of length 3" } */
CPY (d, CHOOSE ("1", "123"), 1); /* { dg-warning ".strncpy\[^\n\r\]* output truncated copying 1 byte from a string of length 1" } */
CPY (d, CHOOSE ("1", "123"), 1); /* { dg-warning ".strncpy\[^\n\r\]* output truncated before terminating nul copying 1 byte from a string of the same length" } */
CPY (d, CHOOSE ("12", "123"), 1); /* { dg-warning ".strncpy\[^\n\r\]* output truncated copying 1 byte from a string of length 2" } */
CPY (d, CHOOSE ("123", "12"), 1); /* { dg-warning ".strncpy\[^\n\r\]* output truncated copying 1 byte from a string of length 2" } */
@ -331,7 +331,7 @@ void test_strncpy_array (Dest *pd, int i, const char* s)
/* This might be better written using memcpy() but it's safe so
it probably shouldn't be diagnosed. It currently triggers
a warning because of bug 81704. */
strncpy (dst7, "0123456", sizeof dst7); /* { dg-bogus "truncated" "bug 81704" { xfail *-*-* } } */
strncpy (dst7, "0123456", sizeof dst7); /* { dg-bogus "\\\[-Wstringop-truncation]" "bug 81704" { xfail *-*-* } } */
dst7[sizeof dst7 - 1] = '\0';
sink (dst7);
}
@ -350,7 +350,7 @@ void test_strncpy_array (Dest *pd, int i, const char* s)
}
{
strncpy (pd->a5, "01234", sizeof pd->a5); /* { dg-bogus "truncated" "bug 81704" { xfail *-*-* } } */
strncpy (pd->a5, "01234", sizeof pd->a5); /* { dg-bogus "\\\[-Wstringop-truncation]" "bug 81704" { xfail *-*-* } } */
pd->a5[sizeof pd->a5 - 1] = '\0';
sink (pd);
}

126
gcc/testsuite/g++.dg/warn/Wstringop-truncation-1.C Normal file
View file

@ -0,0 +1,126 @@
/* PR/tree-optimization/84480 - bogus -Wstringop-truncation despite
assignment with an inlined string literal
{ dg-do compile }
{ dg-options "-O2 -Wstringop-truncation" } */
#include <string.h>
template <size_t N>
class GoodString
{
public:
GoodString (const char *s, size_t slen = N)
{
if (slen > N)
slen = N;
strncpy (str, s, slen);
str[slen] = '\0';
}
private:
char str[N + 1];
};
void sink (void*);
void good_nowarn_size_m2 ()
{
GoodString<3> str ("12");
sink (&str);
}
void good_nowarn_size_m1 ()
{
GoodString<3> str ("123"); // { dg-bogus "\\\[-Wstringop-truncation]" }
sink (&str);
}
void good_nowarn_size_m1_var (const char* s)
{
GoodString<3> str (s); // { dg-bogus "\\\[-Wstringop-truncation]" }
sink (&str);
}
void call_good_nowarn_size_m1_var ()
{
good_nowarn_size_m1_var ("456");
}
template <size_t N>
class BadString1
{
public:
BadString1 (const char *s, size_t slen = N)
{
if (slen > N)
slen = N;
strncpy (str, s, slen);
}
private:
char str[N + 1];
};
void bad1_nowarn_size_m2 ()
{
BadString1<3> str ("12");
sink (&str);
}
template <size_t N>
class BadString2
{
public:
BadString2 (const char *s, size_t slen = N)
{
if (slen > N)
slen = N;
strncpy (str, s, slen); // { dg-warning "\\\[-Wstringop-truncation]" }
}
private:
char str[N + 1];
};
void bad2_warn_size_m1 ()
{
BadString2<3> str ("123");
sink (&str);
}
// { dg-message "inlined from .void bad2_warn_size_m1." "" { target *-*-* } 0 }
template <size_t N>
class BadString3
{
public:
BadString3 (const char *s, size_t slen = N)
{
if (slen > N)
slen = N;
strncpy (str, s, slen); // { dg-warning "\\\[-Wstringop-truncation]" }
}
private:
char str[N + 1];
};
void bad3_warn_size_m1_var (const char *s)
{
BadString3<3> str (s);
sink (&str);
}
void call_bad3_warn_size_m1_var ()
{
bad3_warn_size_m1_var ("456");
}
// { dg-message "inlined from .void call_bad3_warn_size_m1_var." "" { target *-*-* } 0 }

74
gcc/tree-ssa-strlen.c
View file

@ -44,6 +44,7 @@ along with GCC; see the file COPYING3. If not see
#include "domwalk.h"
#include "tree-ssa-alias.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-strlen.h"
#include "params.h"
#include "ipa-chkp.h"
#include "tree-hash-traits.h"
@ -1780,11 +1781,12 @@ is_strlen_related_p (tree src, tree len)
return false;
}
/* A helper of handle_builtin_stxncpy. Check to see if the specified
bound is a) equal to the size of the destination DST and if so, b)
if it's immediately followed by DST[CNT - 1] = '\0'. If a) holds
and b) does not, warn. Otherwise, do nothing. Return true if
diagnostic has been issued.
/* Called by handle_builtin_stxncpy and by gimple_fold_builtin_strncpy
in gimple-fold.c.
Check to see if the specified bound is a) equal to the size of
the destination DST and if so, b) if it's immediately followed by
DST[CNT - 1] = '\0'. If a) holds and b) does not, warn. Otherwise,
do nothing. Return true if diagnostic has been issued.
The purpose is to diagnose calls to strncpy and stpncpy that do
not nul-terminate the copy while allowing for the idiom where
@ -1795,7 +1797,7 @@ is_strlen_related_p (tree src, tree len)
a[sizeof a - 1] = '\0';
*/
static bool
bool
maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
{
gimple *stmt = gsi_stmt (gsi);
@ -1831,8 +1833,11 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
return false;
/* Negative value is the constant string length. If it's less than
the lower bound there is no truncation. */
int sidx = get_stridx (src);
the lower bound there is no truncation. Avoid calling get_stridx()
when ssa_ver_to_stridx is empty. That implies the caller isn't
running under the control of this pass and ssa_ver_to_stridx hasn't
been created yet. */
int sidx = ssa_ver_to_stridx.length () ? get_stridx (src) : 0;
if (sidx < 0 && wi::gtu_p (cntrange[0], ~sidx))
return false;
@ -1935,23 +1940,35 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
lenrange[0] = wi::shwi (0, prec);
}
if (wi::geu_p (lenrange[0], cntrange[1]))
gcall *call = as_a <gcall *> (stmt);
if (lenrange[0] == cntrange[1] && cntrange[0] == cntrange[1])
return warning_at (callloc, OPT_Wstringop_truncation,
(integer_onep (cnt)
? G_("%G%qD output truncated before terminating "
"nul copying %E byte from a string of the "
"same length")
: G_("%G%qD output truncated before terminating nul "
"copying %E bytes from a string of the same "
"length")),
call, func, cnt);
else if (wi::geu_p (lenrange[0], cntrange[1]))
{
/* The shortest string is longer than the upper bound of
the count so the truncation is certain. */
if (cntrange[0] == cntrange[1])
return warning_at (callloc, OPT_Wstringop_truncation,
integer_onep (cnt)
? G_("%qD output truncated copying %E byte "
? G_("%G%qD output truncated copying %E byte "
"from a string of length %wu")
: G_("%qD output truncated copying %E bytes "
: G_("%G%qD output truncated copying %E bytes "
"from a string of length %wu"),
func, cnt, lenrange[0].to_uhwi ());
call, func, cnt, lenrange[0].to_uhwi ());
return warning_at (callloc, OPT_Wstringop_truncation,
"%qD output truncated copying between %wu "
"%G%qD output truncated copying between %wu "
"and %wu bytes from a string of length %wu",
func, cntrange[0].to_uhwi (),
call, func, cntrange[0].to_uhwi (),
cntrange[1].to_uhwi (), lenrange[0].to_uhwi ());
}
else if (wi::geu_p (lenrange[1], cntrange[1]))
@ -1961,16 +1978,16 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
if (cntrange[0] == cntrange[1])
return warning_at (callloc, OPT_Wstringop_truncation,
integer_onep (cnt)
? G_("%qD output may be truncated copying %E "
? G_("%G%qD output may be truncated copying %E "
"byte from a string of length %wu")
: G_("%qD output may be truncated copying %E "
: G_("%G%qD output may be truncated copying %E "
"bytes from a string of length %wu"),
func, cnt, lenrange[1].to_uhwi ());
call, func, cnt, lenrange[1].to_uhwi ());
return warning_at (callloc, OPT_Wstringop_truncation,
"%qD output may be truncated copying between %wu "
"%G%qD output may be truncated copying between %wu "
"and %wu bytes from a string of length %wu",
func, cntrange[0].to_uhwi (),
call, func, cntrange[0].to_uhwi (),
cntrange[1].to_uhwi (), lenrange[1].to_uhwi ());
}
@ -1982,9 +1999,9 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
the lower bound of the specified count but shorter than the
upper bound the copy may (but need not) be truncated. */
return warning_at (callloc, OPT_Wstringop_truncation,
"%qD output may be truncated copying between %wu "
"and %wu bytes from a string of length %wu",
func, cntrange[0].to_uhwi (),
"%G%qD output may be truncated copying between "
"%wu and %wu bytes from a string of length %wu",
call, func, cntrange[0].to_uhwi (),
cntrange[1].to_uhwi (), lenrange[0].to_uhwi ());
}
}
@ -2003,8 +2020,8 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
if (cntrange[0] == cntrange[1])
return warning_at (callloc, OPT_Wstringop_truncation,
"%qD specified bound %E equals destination size",
func, cnt);
"%G%qD specified bound %E equals destination size",
as_a <gcall *> (stmt), func, cnt);
}
return false;
@ -2103,14 +2120,15 @@ handle_builtin_stxncpy (built_in_function, gimple_stmt_iterator *gsi)
if (sisrc == silen
&& is_strlen_related_p (src, len)
&& warning_at (callloc, OPT_Wstringop_truncation,
"%qD output truncated before terminating nul "
"%G%qD output truncated before terminating nul "
"copying as many bytes from a string as its length",
func))
as_a <gcall *>(stmt), func))
warned = true;
else if (silen && is_strlen_related_p (src, silen->ptr))
warned = warning_at (callloc, OPT_Wstringop_overflow_,
"%qD specified bound depends on the length "
"of the source argument", func);
"%G%qD specified bound depends on the length "
"of the source argument",
as_a <gcall *>(stmt), func);
if (warned)
{
location_t strlenloc = pss->second;

26
gcc/tree-ssa-strlen.h Normal file
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@ -0,0 +1,26 @@
/* Declarations of tree-ssa-strlen API.
Copyright (C) 2018 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#ifndef GCC_TREE_SSA_STRLEN_H
#define GCC_TREE_SSA_STRLEN_H
extern bool maybe_diag_stxncpy_trunc (gimple_stmt_iterator, tree, tree);
#endif // GCC_TREE_SSA_STRLEN_H