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· Richard Guenther <rguenther@suse.de> 

2007-01-18  Dirk Mueller  <dmueller@suse.de>
·           Richard Guenther <rguenther@suse.de>

·       PR diagnostic/8268
·       * doc/invoke.texi (Warray-bounds): Document -Warray-bounds.
·       * common.opt (Warray-bounds): Add new warning option.
·       * c-opts.c (c_common_handle_option): Define -Warray-bounds
·       if -Wall is given.
        * Makefile.in: make tree-vrp.o depend on toplev.h
·       * tree-vrp.c (vrp_finalize): Call check_array_refs if -Warray-bounds
·       is enabled.
·       (check_array_refs, check_array_bounds, check_array_ref): New.

·       * gcc.dg/Warray-bounds.c: New testcase.
        * gcc.dg/Warray-bounds-2.c: New testcase.
        * g++.dg/warn/Warray-bounds.C: New testcase.
        * g++.dg/warn/Warray-bounds-2.C: New testcase.

From-SVN: r120898
This commit is contained in:
Dirk Mueller 2007-01-18 13:00:33 +00:00 committed by Dirk Mueller
parent eedeea04da
commit 590b1f2d1f
11 changed files with 400 additions and 3 deletions
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13
gcc/ChangeLog
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@ -1,3 +1,16 @@
2007-01-18 Dirk Mueller <dmueller@suse.de>
· Richard Guenther <rguenther@suse.de>
· PR diagnostic/8268
· * doc/invoke.texi (Warray-bounds): Document -Warray-bounds.
· * common.opt (Warray-bounds): Add new warning option.
· * c-opts.c (c_common_handle_option): Define -Warray-bounds
· if -Wall is given.
* Makefile.in: make tree-vrp.o depend on toplev.h
· * tree-vrp.c (vrp_finalize): Call check_array_refs if -Warray-bounds
· is enabled.
· (check_array_refs, check_array_bounds, check_array_ref): New.
18-01-2007 Jan Hubicka <jh@suse.cz>
* tree-ssa-ccp.c (ccp_finalize): Return if something changed.

2
gcc/Makefile.in
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@ -1862,7 +1862,7 @@ tree-vn.o : tree-vn.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(GGC_H) \
tree-vrp.o : tree-vrp.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
$(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(GGC_H) \
$(BASIC_BLOCK_H) tree-ssa-propagate.h $(FLAGS_H) $(TREE_DUMP_H) \
$(CFGLOOP_H) $(SCEV_H) tree-chrec.h $(TIMEVAR_H)
$(CFGLOOP_H) $(SCEV_H) tree-chrec.h $(TIMEVAR_H) toplev.h
tree-cfg.o : tree-cfg.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
$(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(FLAGS_H) output.h \
$(DIAGNOSTIC_H) $(FUNCTION_H) $(TIMEVAR_H) $(TM_H) coretypes.h \

1
gcc/c-opts.c
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@ -396,6 +396,7 @@ c_common_handle_option (size_t scode, const char *arg, int value)
warn_strict_aliasing = value;
warn_string_literal_comparison = value;
warn_always_true = value;
warn_array_bounds = value;
/* Only warn about unknown pragmas that are not in system
headers. */

4
gcc/common.opt
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@ -61,6 +61,10 @@ Walways-true
Common Var(warn_always_true)
Warn about comparisons that always evaluate to true
Warray-bounds
Common Var(warn_array_bounds)
Warn if an array is accessed out of bounds
Wattributes
Common Var(warn_attributes) Init(1)
Warn about inappropriate attribute usage

11
gcc/doc/invoke.texi
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@ -222,8 +222,8 @@ Objective-C and Objective-C++ Dialects}.
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
-w -Wextra -Wall -Waggregate-return -Walways-true -Wno-attributes @gol
-Wc++-compat -Wcast-align -Wcast-qual -Wchar-subscripts @gol
-w -Wextra -Wall -Waggregate-return -Walways-true -Warray-bounds @gol
-Wno-attributes -Wc++-compat -Wcast-align -Wcast-qual -Wchar-subscripts @gol
-Wclobbered -Wcomment @gol
-Wconversion -Wno-deprecated-declarations @gol
-Wdisabled-optimization -Wno-div-by-zero @gol
@ -2842,6 +2842,13 @@ compiler is using for optimization. This warning catches more cases than
@option{-Wstrict-aliasing}, but it will also give a warning for some ambiguous
cases that are safe.
@item -Warray-bounds
@opindex Wno-array-bounds
@opindex Warray-bounds
This option is only active when @option{-ftree-vrp} is active
(default for -O2 and above). It warns about subscripts to arrays
that are always out of bounds. This warning is enabled by @option{-Wall}.
@item -Wall
@opindex Wall
All of the above @samp{-W} options combined. This enables all the

9
gcc/testsuite/ChangeLog
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@ -1,3 +1,12 @@
2007-01-18 Dirk Mueller <dmueller@suse.de>
· Richard Guenther <rguenther@suse.de>
· PR diagnostic/8268
· * gcc.dg/Warray-bounds.c: New testcase.
* gcc.dg/Warray-bounds-2.c: New testcase.
* g++.dg/warn/Warray-bounds.C: New testcase.
* g++.dg/warn/Warray-bounds-2.C: New testcase.
2007-01-17 Paul Thomas <pault@gcc.gnu.org>
PR fortran/30476

13
gcc/testsuite/g++.dg/warn/Warray-bounds-2.C Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
/* Test that -Warray-bounds is enabled by -Wall */
/* { dg-options "-O2 -Wall" } */
int a[10];
int* f(void) {
a[-1] = 0; /* { dg-warning "array subscript" } */
return a;
}

91
gcc/testsuite/g++.dg/warn/Warray-bounds.C Normal file
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@ -0,0 +1,91 @@
/* { dg-do compile } */
/* { dg-options "-O2 -Warray-bounds" } */
int a[10];
static inline int n(void) {
__SIZE_TYPE__ strlen(const char *s);
return strlen("12345");
}
void g(int *p);
void h(int p);
int* f(void) {
int b[10];
int i;
struct {
int c[10];
} c;
a[-1] = 0; /* { dg-warning "array subscript" } */
a[ 0] = 0;
a[ 1] = 0;
a[ 9] = 0;
a[10] = 0; /* { dg-warning "array subscript" } */
a[11] = 0; /* { dg-warning "array subscript" } */
a[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
a[2 * n() - 10] = 0;
a[2 * n() - 1] = 0;
a[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
b[-1] = 0; /* { dg-warning "array subscript" } */
b[ 0] = 0;
b[ 1] = 0;
b[ 9] = 0;
b[10] = 0; /* { dg-warning "array subscript" } */
b[11] = 0; /* { dg-warning "array subscript" } */
b[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
b[2 * n() - 10] = 0;
b[2 * n() - 1] = 0;
b[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
c.c[-1] = 0; /* { dg-warning "array subscript" } */
c.c[ 0] = 0;
c.c[ 1] = 0;
c.c[ 9] = 0;
c.c[10] = 0; /* { dg-warning "array subscript" } */
c.c[11] = 0; /* { dg-warning "array subscript" } */
c.c[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
c.c[2 * n() - 10] = 0;
c.c[2 * n() - 1] = 0;
c.c[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
g(&a[8]);
g(&a[9]);
g(&a[10]);
g(&a[11]); /* { dg-warning "array subscript" } */
g(&a[-30]+10); /* { dg-warning "array subscript" } */
g(&a[-30]+30);
g(&b[10]);
g(&c.c[10]);
g(&a[11]); /* { dg-warning "array subscript" } */
g(&b[11]); /* { dg-warning "array subscript" } */
g(&c.c[11]); /* { dg-warning "array subscript" } */
g(&a[0]);
g(&b[0]);
g(&c.c[0]);
g(&a[-1]); /* { dg-warning "array subscript" } */
g(&b[-1]); /* { dg-warning "array subscript" } */
h(sizeof a[-1]);
h(sizeof a[10]);
h(sizeof b[-1]);
h(sizeof b[10]);
h(sizeof c.c[-1]);
h(sizeof c.c[10]);
if (10 < 10)
a[10] = 0;
if (10 < 10)
b[10] = 0;
if (-1 >= 0)
c.c[-1] = 0;
return a;
}

13
gcc/testsuite/gcc.dg/Warray-bounds-2.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
/* Test that -Warray-bounds is enabled by -Wall */
/* { dg-options "-O2 -Wall" } */
int a[10];
int* f(void) {
a[-1] = 0; /* { dg-warning "array subscript" } */
return a;
}

94
gcc/testsuite/gcc.dg/Warray-bounds.c Normal file
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@ -0,0 +1,94 @@
/* { dg-do compile } */
/* { dg-options "-O2 -Warray-bounds" } */
int a[10];
static inline int n(void) {
__SIZE_TYPE__ strlen(const char *s);
return strlen("12345");
}
void g(int *p);
void h(int p);
int* f(void) {
int b[10];
int i;
struct {
int c[10];
} c;
a[-1] = 0; /* { dg-warning "array subscript" } */
a[ 0] = 0;
a[ 1] = 0;
a[ 9] = 0;
a[10] = 0; /* { dg-warning "array subscript" } */
a[11] = 0; /* { dg-warning "array subscript" } */
a[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
a[2 * n() - 10] = 0;
a[2 * n() - 1] = 0;
a[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
b[-1] = 0; /* { dg-warning "array subscript" } */
b[ 0] = 0;
b[ 1] = 0;
b[ 9] = 0;
b[10] = 0; /* { dg-warning "array subscript" } */
b[11] = 0; /* { dg-warning "array subscript" } */
b[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
b[2 * n() - 10] = 0;
b[2 * n() - 1] = 0;
b[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
c.c[-1] = 0; /* { dg-warning "array subscript" } */
c.c[ 0] = 0;
c.c[ 1] = 0;
c.c[ 9] = 0;
c.c[10] = 0; /* { dg-warning "array subscript" } */
c.c[11] = 0; /* { dg-warning "array subscript" } */
c.c[2 * n() - 11] = 0; /* { dg-warning "array subscript" } */
c.c[2 * n() - 10] = 0;
c.c[2 * n() - 1] = 0;
c.c[2 * n() - 0] = 0; /* { dg-warning "array subscript" } */
g(&a[8]);
g(&a[9]);
g(&a[10]);
g(&a[11]); /* { dg-warning "array subscript" } */
g(&a[-30]+10); /* { dg-warning "array subscript" } */
g(&a[-30]+30);
g(&b[10]);
g(&c.c[10]);
g(&a[11]); /* { dg-warning "array subscript" } */
g(&b[11]); /* { dg-warning "array subscript" } */
g(&c.c[11]); /* { dg-warning "array subscript" } */
g(&a[0]);
g(&b[0]);
g(&c.c[0]);
g(&a[-1]); /* { dg-warning "array subscript" } */
g(&b[-1]); /* { dg-warning "array subscript" } */
h(sizeof a[-1]);
h(sizeof a[10]);
h(sizeof b[-1]);
h(sizeof b[10]);
h(sizeof c.c[-1]);
h(sizeof c.c[10]);
if (10 < 10)
a[10] = 0;
if (10 < 10)
b[10] = 0;
if (-1 >= 0)
c.c[-1] = 0;
for (i = 20; i < 30; ++i)
a[i] = 1; /* { dg-warning "array subscript" } */
return a;
}

152
gcc/tree-vrp.c
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@ -32,6 +32,7 @@ Boston, MA 02110-1301, USA. */
#include "tree-dump.h"
#include "timevar.h"
#include "diagnostic.h"
#include "toplev.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-propagate.h"
@ -3478,6 +3479,154 @@ insert_range_assertions (void)
BITMAP_FREE (need_assert_for);
}
/* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
and "struct" hacks. If VRP can determine that the
array subscript is a contant, check if it is outside valid
range. If the array subscript is a RANGE, warn if it is
non-overlapping with valid range.
IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */
static void
check_array_ref (tree ref, location_t* locus, bool ignore_off_by_one)
{
value_range_t* vr = NULL;
tree low_sub, up_sub;
tree low_bound, up_bound = array_ref_up_bound (ref);
low_sub = up_sub = TREE_OPERAND (ref, 1);
if (!up_bound || !locus || TREE_NO_WARNING (ref)
|| TREE_CODE (up_bound) != INTEGER_CST
/* Can not check flexible arrays. */
|| (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE
&& TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE
&& TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE)
/* Accesses after the end of arrays of size 0 (gcc
extension) and 1 are likely intentional ("struct
hack"). */
|| compare_tree_int (up_bound, 1) <= 0)
return;
low_bound = array_ref_low_bound (ref);
if (TREE_CODE (low_sub) == SSA_NAME)
{
vr = get_value_range (low_sub);
if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
{
low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
}
}
if (vr && vr->type == VR_ANTI_RANGE)
{
if (TREE_CODE (up_sub) == INTEGER_CST
&& tree_int_cst_lt (up_bound, up_sub)
&& TREE_CODE (low_sub) == INTEGER_CST
&& tree_int_cst_lt (low_sub, low_bound))
{
warning (OPT_Warray_bounds,
"%Harray subscript is outside array bounds", locus);
TREE_NO_WARNING (ref) = 1;
}
}
else if (TREE_CODE (up_sub) == INTEGER_CST
&& tree_int_cst_lt (up_bound, up_sub)
&& !tree_int_cst_equal (up_bound, up_sub)
&& (!ignore_off_by_one
|| !tree_int_cst_equal (int_const_binop (PLUS_EXPR,
up_bound,
integer_one_node,
0),
up_sub)))
{
warning (OPT_Warray_bounds, "%Harray subscript is above array bounds",
locus);
TREE_NO_WARNING (ref) = 1;
}
else if (TREE_CODE (low_sub) == INTEGER_CST
&& tree_int_cst_lt (low_sub, low_bound))
{
warning (OPT_Warray_bounds, "%Harray subscript is below array bounds",
locus);
TREE_NO_WARNING (ref) = 1;
}
}
/* walk_tree() callback that checks if *TP is
an ARRAY_REF inside an ADDR_EXPR (in which an array
subscript one outside the valid range is allowed). Call
check_array_ref for each ARRAY_REF found. The location is
passed in DATA. */
static tree
check_array_bounds (tree *tp, int *walk_subtree, void *data)
{
tree t = *tp;
location_t *location = EXPR_LOCUS ((tree) data);
*walk_subtree = TRUE;
if (TREE_CODE (t) == ARRAY_REF)
check_array_ref (t, location, false /*ignore_off_by_one*/);
else if (TREE_CODE (t) == ADDR_EXPR)
{
t = TREE_OPERAND (t, 0);
/* Don't warn on statements like
ssa_name = 500 + &array[-200] which are sometimes
produced by various optimizing passes. */
if (TREE_CODE ((tree)data) == GIMPLE_MODIFY_STMT
&& BINARY_CLASS_P (GIMPLE_STMT_OPERAND ((tree)data, 1)))
{
*walk_subtree = FALSE;
return NULL_TREE;
}
while (handled_component_p (t))
{
if (TREE_CODE (t) == ARRAY_REF)
check_array_ref (t, location, true /*ignore_off_by_one*/);
t = TREE_OPERAND (t, 0);
}
*walk_subtree = FALSE;
}
return NULL_TREE;
}
/* Walk over all statements of all reachable BBs and call check_array_bounds
on them. */
static void
check_all_array_refs (void)
{
basic_block bb;
block_stmt_iterator si;
FOR_EACH_BB (bb)
{
/* Skip bb's that are clearly unreachable. */
if (single_pred_p (bb))
{
basic_block pred_bb = EDGE_PRED (bb, 0)->src;
tree ls = NULL_TREE;
if (!bsi_end_p (bsi_last (pred_bb)))
ls = bsi_stmt (bsi_last (pred_bb));
if (ls && TREE_CODE (ls) == COND_EXPR
&& ((COND_EXPR_COND (ls) == boolean_false_node
&& (EDGE_PRED (bb, 0)->flags & EDGE_TRUE_VALUE))
|| (COND_EXPR_COND (ls) == boolean_true_node
&& (EDGE_PRED (bb, 0)->flags & EDGE_FALSE_VALUE))))
continue;
}
for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
walk_tree (bsi_stmt_ptr (si), check_array_bounds,
bsi_stmt (si), NULL);
}
}
/* Convert range assertion expressions into the implied copies and
copy propagate away the copies. Doing the trivial copy propagation
@ -4797,6 +4946,9 @@ vrp_finalize (void)
substitute_and_fold (single_val_range, true);
if (warn_array_bounds)
check_all_array_refs();
/* We must identify jump threading opportunities before we release
the datastructures built by VRP. */
identify_jump_threads ();