| Message ID | 20141112081405.GE29791@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Wed, 12 Nov 2014, Marek Polacek wrote: > On Tue, Nov 11, 2014 at 07:45:40PM +0100, Richard Biener wrote: > > On November 11, 2014 6:49:34 PM CET, Jakub Jelinek <jakub@redhat.com> wrote: > > >On Tue, Nov 11, 2014 at 06:40:25PM +0100, Marek Polacek wrote: > > >> --- gcc/fold-const.c > > >> +++ gcc/fold-const.c > > >> @@ -7862,9 +7862,15 @@ fold_unary_loc (location_t loc, enum tree_code > > >code, tree type, tree op0) > > >> return fold_view_convert_expr (type, op0); > > >> > > >> case NEGATE_EXPR: > > >> - tem = fold_negate_expr (loc, arg0); > > >> - if (tem) > > >> - return fold_convert_loc (loc, type, tem); > > >> + if (TREE_CODE (arg0) == INTEGER_CST > > >> + || TREE_CODE (arg0) == REAL_CST > > >> + || TYPE_OVERFLOW_WRAPS (type) > > >> + || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0) > > >> + { > > >> + tem = fold_negate_expr (loc, arg0); > > >> + if (tem) > > >> + return fold_convert_loc (loc, type, tem); > > >> + } > > > > > >a) if arg0 is INTEGER_CST, but e.g. INT_MIN, should we > > > really fold it for -fsanitize=signed-integer-overflow > > > (I'd say in that case we should fold only if it is not > > > the minimum value) > > Ok. We don't sanitize constant folded expressions (e.g. INT_MAX + > 1), but this can be easily done. > > > Right. I think you should fix VRP instead. > > With the following no VRP tweaks are needed (I hope). > > > >b) if the argument is not INTEGRAL_TYPE_P (type), shouldn't > > > we fold no matter what flag_sanitize says? Is the REAL_CST > > > case needed in that case? > > > > Yes and no I guess. > > Done. > > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > 2014-11-12 Marek Polacek <polacek@redhat.com> > > * fold-const.c (fold_unary_loc): Don't call fold_negate_expr > when the result is undefined. > > * c-c++-common/ubsan/overflow-negate-3.c: New test. > > diff --git gcc/fold-const.c gcc/fold-const.c > index 756f469..3688f5a 100644 > --- gcc/fold-const.c > +++ gcc/fold-const.c > @@ -7854,9 +7854,16 @@ fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0) > return fold_view_convert_expr (type, op0); > > case NEGATE_EXPR: > - tem = fold_negate_expr (loc, arg0); > - if (tem) > - return fold_convert_loc (loc, type, tem); > + if (!INTEGRAL_TYPE_P (type) > + || (TREE_CODE (arg0) == INTEGER_CST > + && !tree_int_cst_equal (arg0, TYPE_MIN_VALUE (type))) > + || TYPE_OVERFLOW_WRAPS (type) > + || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0) > + { > + tem = fold_negate_expr (loc, arg0); > + if (tem) > + return fold_convert_loc (loc, type, tem); > + } > return NULL_TREE; Err - please adjust fold_negate_expr instead. Richard. > case ABS_EXPR: > diff --git gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c > index e69de29..e6db394 100644 > --- gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c > +++ gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c > @@ -0,0 +1,21 @@ > +/* { dg-do run } */ > +/* { dg-options "-fsanitize=signed-integer-overflow" } */ > + > +#define INT_MIN (-__INT_MAX__ - 1) > + > +int > +main () > +{ > + int x = INT_MIN; > + int y; > + asm ("" : "+g" (x)); > + y = -(-x); > + asm ("" : "+g" (y)); > + y = -(-INT_MIN); > + asm ("" : "+g" (y)); > +} > + > +/* { dg-output "negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ > +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ > +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ > +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ > > Marek > >
diff --git gcc/fold-const.c gcc/fold-const.c index 756f469..3688f5a 100644 --- gcc/fold-const.c +++ gcc/fold-const.c @@ -7854,9 +7854,16 @@ fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0) return fold_view_convert_expr (type, op0); case NEGATE_EXPR: - tem = fold_negate_expr (loc, arg0); - if (tem) - return fold_convert_loc (loc, type, tem); + if (!INTEGRAL_TYPE_P (type) + || (TREE_CODE (arg0) == INTEGER_CST + && !tree_int_cst_equal (arg0, TYPE_MIN_VALUE (type))) + || TYPE_OVERFLOW_WRAPS (type) + || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0) + { + tem = fold_negate_expr (loc, arg0); + if (tem) + return fold_convert_loc (loc, type, tem); + } return NULL_TREE; case ABS_EXPR: diff --git gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c index e69de29..e6db394 100644 --- gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c +++ gcc/testsuite/c-c++-common/ubsan/overflow-negate-3.c @@ -0,0 +1,21 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=signed-integer-overflow" } */ + +#define INT_MIN (-__INT_MAX__ - 1) + +int +main () +{ + int x = INT_MIN; + int y; + asm ("" : "+g" (x)); + y = -(-x); + asm ("" : "+g" (y)); + y = -(-INT_MIN); + asm ("" : "+g" (y)); +} + +/* { dg-output "negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*negation of -2147483648 cannot be represented in type 'int'\[^\n\r]*; cast to an unsigned type to negate this value to itself\[^\n\r]*(\n|\r\n|\r)" } */