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c-ubsan.c (ubsan_instrument_shift): Perform the MINUS_EXPR in unsigned type.

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* c-ubsan.c (ubsan_instrument_shift): Perform the MINUS_EXPR
	in unsigned type.

	* c-c++-common/ubsan/undefined-2.c: New test.

From-SVN: r216593
This commit is contained in:
Marek Polacek 2014-10-23 13:02:02 +00:00 • committed by Marek Polacek
parent 0c9ef7adf7
commit 59d7607aec
4 changed files with 37 additions and 5 deletions
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5
gcc/c-family/ChangeLog
View file

@ -1,3 +1,8 @@
2014-10-23 Marek Polacek <polacek@redhat.com>
* c-ubsan.c (ubsan_instrument_shift): Perform the MINUS_EXPR
in unsigned type.
2014-10-22 Jakub Jelinek <jakub@redhat.com>
Yury Gribov <y.gribov@samsung.com>

11
gcc/c-family/c-ubsan.c
View file

@ -128,19 +128,19 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
tree op1_utype = unsigned_type_for (type1);
HOST_WIDE_INT op0_prec = TYPE_PRECISION (type0);
tree uprecm1 = build_int_cst (op1_utype, op0_prec - 1);
tree precm1 = build_int_cst (type1, op0_prec - 1);
t = fold_convert_loc (loc, op1_utype, op1);
t = fold_build2 (GT_EXPR, boolean_type_node, t, uprecm1);
/* For signed x << y, in C99/C11, the following:
(unsigned) x >> (precm1 - y)
(unsigned) x >> (uprecm1 - y)
if non-zero, is undefined. */
if (code == LSHIFT_EXPR
&& !TYPE_UNSIGNED (type0)
&& flag_isoc99)
{
tree x = fold_build2 (MINUS_EXPR, integer_type_node, precm1, op1);
tree x = fold_build2 (MINUS_EXPR, unsigned_type_node, uprecm1,
fold_convert (op1_utype, op1));
tt = fold_convert_loc (loc, unsigned_type_for (type0), op0);
tt = fold_build2 (RSHIFT_EXPR, TREE_TYPE (tt), tt, x);
tt = fold_build2 (NE_EXPR, boolean_type_node, tt,
@ -148,13 +148,14 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
}
/* For signed x << y, in C++11 and later, the following:
x < 0 || ((unsigned) x >> (precm1 - y))
x < 0 || ((unsigned) x >> (uprecm1 - y))
if > 1, is undefined. */
if (code == LSHIFT_EXPR
&& !TYPE_UNSIGNED (TREE_TYPE (op0))
&& (cxx_dialect >= cxx11))
{
tree x = fold_build2 (MINUS_EXPR, integer_type_node, precm1, op1);
tree x = fold_build2 (MINUS_EXPR, unsigned_type_node, uprecm1,
fold_convert (op1_utype, op1));
tt = fold_convert_loc (loc, unsigned_type_for (type0), op0);
tt = fold_build2 (RSHIFT_EXPR, TREE_TYPE (tt), tt, x);
tt = fold_build2 (GT_EXPR, boolean_type_node, tt,

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2014-10-23 Marek Polacek <polacek@redhat.com>
* c-c++-common/ubsan/undefined-2.c: New test.
2014-10-10 Kirill Yukhin <kirill.yukhin@intel.com>
* gcc.target/i386/pr63600.c: New.

22
gcc/testsuite/c-c++-common/ubsan/undefined-2.c Normal file
View file

@ -0,0 +1,22 @@
/* { dg-do run } */
/* { dg-options "-fsanitize=undefined -fno-sanitize-recover=signed-integer-overflow" } */
/* { dg-additional-options "-std=gnu11" { target c } } */
/* { dg-additional-options "-std=c++11" { target c++ } } */
volatile int w, z;
__attribute__ ((noinline, noclone)) int
foo (int x, int y)
{
z++;
return x << y;
}
int
main ()
{
w = foo (0, -__INT_MAX__);
return 0;
}
/* { dg-output "shift exponent -\[^\n\r]* is negative\[^\n\r]*(\n|\r\n|\r)" } */