* [PATCH] Fix PR56344
@ 2013-02-26 18:27 Marek Polacek
2013-02-26 23:17 ` Joseph S. Myers
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-02-26 18:27 UTC (permalink / raw)
To: GCC Patches
This "fixes" PR56344 by prohibiting passing arguments by value
of size >= 2^30 bytes. Probably no sane programmer would want to
do that, but it's better to issue an error than to segfault.
This would be a good opportunity to use __builtin_expect, but
we don't use that much in the codebase...
Regtested/bootstrapped on x86_64-linux, ok for trunk?
Do we need a testcase for this (compiling it is quite slow)?
2013-02-26 Marek Polacek <polacek@redhat.com>
PR middle-end/56344
* calls.c (expand_call): Disallow passing huge arguments
by value.
--- gcc/calls.c.mp 2013-02-26 17:04:33.159555349 +0100
+++ gcc/calls.c 2013-02-26 18:50:54.864084545 +0100
@@ -3037,6 +3037,14 @@ expand_call (tree exp, rtx target, int i
{
rtx before_arg = get_last_insn ();
+ /* We don't allow passing huge (> 2^30 B) arguments
+ by value. It would cause an overflow later on. */
+ if (adjusted_args_size.constant >= (1 << 30))
+ {
+ error ("passing too large argument on stack");
+ continue;
+ }
+
if (store_one_arg (&args[i], argblock, flags,
adjusted_args_size.var != 0,
reg_parm_stack_space)
Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-02-26 18:27 [PATCH] Fix PR56344 Marek Polacek
@ 2013-02-26 23:17 ` Joseph S. Myers
2013-02-27 9:56 ` Marek Polacek
0 siblings, 1 reply; 12+ messages in thread
From: Joseph S. Myers @ 2013-02-26 23:17 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
On Tue, 26 Feb 2013, Marek Polacek wrote:
> + /* We don't allow passing huge (> 2^30 B) arguments
> + by value. It would cause an overflow later on. */
> + if (adjusted_args_size.constant >= (1 << 30))
> + {
> + error ("passing too large argument on stack");
> + continue;
This should be sorry () not error (), as a compiler limitation rather than
a defect in the user's program. (And is input_location set to something
useful here so the diagnostic points to the argument in question rather
than e.g. to the end of the function containing the problem call?)
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-02-26 23:17 ` Joseph S. Myers
@ 2013-02-27 9:56 ` Marek Polacek
2013-02-27 11:33 ` Richard Biener
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-02-27 9:56 UTC (permalink / raw)
To: Joseph S. Myers; +Cc: GCC Patches
On Tue, Feb 26, 2013 at 11:17:22PM +0000, Joseph S. Myers wrote:
> On Tue, 26 Feb 2013, Marek Polacek wrote:
>
> > + /* We don't allow passing huge (> 2^30 B) arguments
> > + by value. It would cause an overflow later on. */
> > + if (adjusted_args_size.constant >= (1 << 30))
> > + {
> > + error ("passing too large argument on stack");
> > + continue;
>
> This should be sorry () not error (), as a compiler limitation rather than
> a defect in the user's program. (And is input_location set to something
> useful here so the diagnostic points to the argument in question rather
> than e.g. to the end of the function containing the problem call?)
Okay, changed back to sorry (). I'd think that input_location is fine
here, for e.g.
struct S { unsigned char s[1 << 30]; } s;
extern void foo (struct S);
void
bar (void)
{
foo (s);
}
we get:
pr56344.c: In function ‘bar’:
pr56344.c:7:7: sorry, unimplemented: passing too large argument on stack
foo (s);
^
Ok now?
2013-02-27 Marek Polacek <polacek@redhat.com>
PR middle-end/56344
* calls.c (expand_call): Disallow passing huge arguments
by value.
--- gcc/calls.c.mp 2013-02-26 17:04:33.159555349 +0100
+++ gcc/calls.c 2013-02-27 10:44:02.254461200 +0100
@@ -3037,6 +3037,14 @@ expand_call (tree exp, rtx target, int i
{
rtx before_arg = get_last_insn ();
+ /* We don't allow passing huge (> 2^30 B) arguments
+ by value. It would cause an overflow later on. */
+ if (adjusted_args_size.constant >= (1 << 30))
+ {
+ sorry ("passing too large argument on stack");
+ continue;
+ }
+
if (store_one_arg (&args[i], argblock, flags,
adjusted_args_size.var != 0,
reg_parm_stack_space)
Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-02-27 9:56 ` Marek Polacek
@ 2013-02-27 11:33 ` Richard Biener
2013-02-27 17:38 ` Joseph S. Myers
0 siblings, 1 reply; 12+ messages in thread
From: Richard Biener @ 2013-02-27 11:33 UTC (permalink / raw)
To: Marek Polacek; +Cc: Joseph S. Myers, GCC Patches
On Wed, Feb 27, 2013 at 10:56 AM, Marek Polacek <polacek@redhat.com> wrote:
> On Tue, Feb 26, 2013 at 11:17:22PM +0000, Joseph S. Myers wrote:
>> On Tue, 26 Feb 2013, Marek Polacek wrote:
>>
>> > + /* We don't allow passing huge (> 2^30 B) arguments
>> > + by value. It would cause an overflow later on. */
>> > + if (adjusted_args_size.constant >= (1 << 30))
>> > + {
>> > + error ("passing too large argument on stack");
>> > + continue;
>>
>> This should be sorry () not error (), as a compiler limitation rather than
>> a defect in the user's program. (And is input_location set to something
>> useful here so the diagnostic points to the argument in question rather
>> than e.g. to the end of the function containing the problem call?)
>
> Okay, changed back to sorry (). I'd think that input_location is fine
> here, for e.g.
>
> struct S { unsigned char s[1 << 30]; } s;
> extern void foo (struct S);
>
> void
> bar (void)
> {
> foo (s);
> }
>
> we get:
> pr56344.c: In function ‘bar’:
> pr56344.c:7:7: sorry, unimplemented: passing too large argument on stack
> foo (s);
> ^
>
> Ok now?
Wouldn't it be better to simply pass this using the variable size handling
code? Thus, initialize args_size.var for too large constant size instead?
Also args_size.constant is HOST_WIDE_INT, so I'm not sure where you
derive the magic number 1<<30 from. I'd expect it to be sth like
if (!host_integer_p (bit-size, 1))
init variable-size
this has the advantage to move the error to runtime instead of compile-time
which is better than rejecting valid C code that will work when it is
not executed
at runtime.
Richard.
> 2013-02-27 Marek Polacek <polacek@redhat.com>
>
> PR middle-end/56344
> * calls.c (expand_call): Disallow passing huge arguments
> by value.
>
> --- gcc/calls.c.mp 2013-02-26 17:04:33.159555349 +0100
> +++ gcc/calls.c 2013-02-27 10:44:02.254461200 +0100
> @@ -3037,6 +3037,14 @@ expand_call (tree exp, rtx target, int i
> {
> rtx before_arg = get_last_insn ();
>
> + /* We don't allow passing huge (> 2^30 B) arguments
> + by value. It would cause an overflow later on. */
> + if (adjusted_args_size.constant >= (1 << 30))
> + {
> + sorry ("passing too large argument on stack");
> + continue;
> + }
> +
> if (store_one_arg (&args[i], argblock, flags,
> adjusted_args_size.var != 0,
> reg_parm_stack_space)
>
> Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-02-27 11:33 ` Richard Biener
@ 2013-02-27 17:38 ` Joseph S. Myers
2013-03-01 8:41 ` Richard Biener
0 siblings, 1 reply; 12+ messages in thread
From: Joseph S. Myers @ 2013-02-27 17:38 UTC (permalink / raw)
To: Richard Biener; +Cc: Marek Polacek, GCC Patches
On Wed, 27 Feb 2013, Richard Biener wrote:
> Wouldn't it be better to simply pass this using the variable size handling
> code? Thus, initialize args_size.var for too large constant size instead?
Would that be compatible with the ABI definition of how a large (constant
size) argument should be passed?
--
Joseph S. Myers
joseph@codesourcery.com
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-02-27 17:38 ` Joseph S. Myers
@ 2013-03-01 8:41 ` Richard Biener
2013-03-05 16:06 ` Marek Polacek
0 siblings, 1 reply; 12+ messages in thread
From: Richard Biener @ 2013-03-01 8:41 UTC (permalink / raw)
To: Joseph S. Myers; +Cc: Marek Polacek, GCC Patches
On Wed, Feb 27, 2013 at 6:38 PM, Joseph S. Myers
<joseph@codesourcery.com> wrote:
> On Wed, 27 Feb 2013, Richard Biener wrote:
>
>> Wouldn't it be better to simply pass this using the variable size handling
>> code? Thus, initialize args_size.var for too large constant size instead?
>
> Would that be compatible with the ABI definition of how a large (constant
> size) argument should be passed?
I'm not sure. Another alternative is to expand to __builtin_trap (), but that's
probably not easy at this very point.
Or simply fix the size calculation to not overflow (either don't count bits
or use a double-int).
Richard.
> --
> Joseph S. Myers
> joseph@codesourcery.com
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-03-01 8:41 ` Richard Biener
@ 2013-03-05 16:06 ` Marek Polacek
2013-03-13 12:57 ` Marek Polacek
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-03-05 16:06 UTC (permalink / raw)
To: Richard Biener; +Cc: Joseph S. Myers, GCC Patches
On Fri, Mar 01, 2013 at 09:41:27AM +0100, Richard Biener wrote:
> On Wed, Feb 27, 2013 at 6:38 PM, Joseph S. Myers
> <joseph@codesourcery.com> wrote:
> > On Wed, 27 Feb 2013, Richard Biener wrote:
> >
> >> Wouldn't it be better to simply pass this using the variable size handling
> >> code? Thus, initialize args_size.var for too large constant size instead?
> >
> > Would that be compatible with the ABI definition of how a large (constant
> > size) argument should be passed?
>
> I'm not sure. Another alternative is to expand to __builtin_trap (), but that's
> probably not easy at this very point.
>
> Or simply fix the size calculation to not overflow (either don't count bits
> or use a double-int).
I don't think double_int will help us here. We won't detect overflow,
because we overflowed here (when lower_bound is an int):
lower_bound = INTVAL (XEXP (XEXP (arg->stack_slot, 0), 1));
The value from INTVAL () fits when lower_bound is a double_int, but
then:
i = lower_bound;
...
stack_usage_map[i]
the size of stack_usage_map is stored in highest_outgoing_arg_in_use,
which is an int, so we're limited by an int size here.
Changing the type of highest_outgoing_arg_in_use from an int to a
double_int isn't worth the trouble, IMHO.
Maybe the original approach, only with sorry () instead of error ()
and e.g. HOST_BITS_PER_INT - 1 instead of 30 would be appropriate
after all. Dunno.
Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-03-05 16:06 ` Marek Polacek
@ 2013-03-13 12:57 ` Marek Polacek
2013-12-02 15:01 ` Richard Biener
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-03-13 12:57 UTC (permalink / raw)
To: Richard Biener; +Cc: Joseph S. Myers, GCC Patches
Ping.
On Tue, Mar 05, 2013 at 05:06:21PM +0100, Marek Polacek wrote:
> On Fri, Mar 01, 2013 at 09:41:27AM +0100, Richard Biener wrote:
> > On Wed, Feb 27, 2013 at 6:38 PM, Joseph S. Myers
> > <joseph@codesourcery.com> wrote:
> > > On Wed, 27 Feb 2013, Richard Biener wrote:
> > >
> > >> Wouldn't it be better to simply pass this using the variable size handling
> > >> code? Thus, initialize args_size.var for too large constant size instead?
> > >
> > > Would that be compatible with the ABI definition of how a large (constant
> > > size) argument should be passed?
> >
> > I'm not sure. Another alternative is to expand to __builtin_trap (), but that's
> > probably not easy at this very point.
> >
> > Or simply fix the size calculation to not overflow (either don't count bits
> > or use a double-int).
>
> I don't think double_int will help us here. We won't detect overflow,
> because we overflowed here (when lower_bound is an int):
> lower_bound = INTVAL (XEXP (XEXP (arg->stack_slot, 0), 1));
> The value from INTVAL () fits when lower_bound is a double_int, but
> then:
> i = lower_bound;
> ...
> stack_usage_map[i]
> the size of stack_usage_map is stored in highest_outgoing_arg_in_use,
> which is an int, so we're limited by an int size here.
> Changing the type of highest_outgoing_arg_in_use from an int to a
> double_int isn't worth the trouble, IMHO.
>
> Maybe the original approach, only with sorry () instead of error ()
> and e.g. HOST_BITS_PER_INT - 1 instead of 30 would be appropriate
> after all. Dunno.
>
> Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-03-13 12:57 ` Marek Polacek
@ 2013-12-02 15:01 ` Richard Biener
2013-12-02 16:40 ` Marek Polacek
0 siblings, 1 reply; 12+ messages in thread
From: Richard Biener @ 2013-12-02 15:01 UTC (permalink / raw)
To: Marek Polacek; +Cc: Joseph S. Myers, GCC Patches
On Wed, Mar 13, 2013 at 1:57 PM, Marek Polacek <polacek@redhat.com> wrote:
> Ping.
Ok. (yay, oldest patch in my review queue ...)
Thanks,
Richard.
> On Tue, Mar 05, 2013 at 05:06:21PM +0100, Marek Polacek wrote:
>> On Fri, Mar 01, 2013 at 09:41:27AM +0100, Richard Biener wrote:
>> > On Wed, Feb 27, 2013 at 6:38 PM, Joseph S. Myers
>> > <joseph@codesourcery.com> wrote:
>> > > On Wed, 27 Feb 2013, Richard Biener wrote:
>> > >
>> > >> Wouldn't it be better to simply pass this using the variable size handling
>> > >> code? Thus, initialize args_size.var for too large constant size instead?
>> > >
>> > > Would that be compatible with the ABI definition of how a large (constant
>> > > size) argument should be passed?
>> >
>> > I'm not sure. Another alternative is to expand to __builtin_trap (), but that's
>> > probably not easy at this very point.
>> >
>> > Or simply fix the size calculation to not overflow (either don't count bits
>> > or use a double-int).
>>
>> I don't think double_int will help us here. We won't detect overflow,
>> because we overflowed here (when lower_bound is an int):
>> lower_bound = INTVAL (XEXP (XEXP (arg->stack_slot, 0), 1));
>> The value from INTVAL () fits when lower_bound is a double_int, but
>> then:
>> i = lower_bound;
>> ...
>> stack_usage_map[i]
>> the size of stack_usage_map is stored in highest_outgoing_arg_in_use,
>> which is an int, so we're limited by an int size here.
>> Changing the type of highest_outgoing_arg_in_use from an int to a
>> double_int isn't worth the trouble, IMHO.
>>
>> Maybe the original approach, only with sorry () instead of error ()
>> and e.g. HOST_BITS_PER_INT - 1 instead of 30 would be appropriate
>> after all. Dunno.
>>
>> Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-12-02 15:01 ` Richard Biener
@ 2013-12-02 16:40 ` Marek Polacek
2013-12-02 19:19 ` Marek Polacek
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-12-02 16:40 UTC (permalink / raw)
To: Richard Biener; +Cc: Joseph S. Myers, GCC Patches
On Mon, Dec 02, 2013 at 04:01:05PM +0100, Richard Biener wrote:
> On Wed, Mar 13, 2013 at 1:57 PM, Marek Polacek <polacek@redhat.com> wrote:
> > Ping.
>
> Ok. (yay, oldest patch in my review queue ...)
;) thanks. Just to be sure, did you mean to ok this patch (that is,
the one with HOST_BITS_PER_INT)?
Bootstrap/regtest in progress.
2013-12-02 Marek Polacek <polacek@redhat.com>
PR middle-end/56344
* calls.c (expand_call): Disallow passing huge arguments
by value.
--- gcc/calls.c.mp4 2013-12-02 17:12:18.621057873 +0100
+++ gcc/calls.c 2013-12-02 17:32:35.523684716 +0100
@@ -3047,6 +3047,15 @@ expand_call (tree exp, rtx target, int i
{
rtx before_arg = get_last_insn ();
+ /* We don't allow passing huge (> 2^30 B) arguments
+ by value. It would cause an overflow later on. */
+ if (adjusted_args_size.constant
+ >= (1 << (HOST_BITS_PER_INT - 1)))
+ {
+ sorry ("passing too large argument on stack");
+ continue;
+ }
+
if (store_one_arg (&args[i], argblock, flags,
adjusted_args_size.var != 0,
reg_parm_stack_space)
Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-12-02 16:40 ` Marek Polacek
@ 2013-12-02 19:19 ` Marek Polacek
2013-12-02 20:35 ` Richard Biener
0 siblings, 1 reply; 12+ messages in thread
From: Marek Polacek @ 2013-12-02 19:19 UTC (permalink / raw)
To: Richard Biener; +Cc: Joseph S. Myers, GCC Patches
On Mon, Dec 02, 2013 at 05:40:33PM +0100, Marek Polacek wrote:
> On Mon, Dec 02, 2013 at 04:01:05PM +0100, Richard Biener wrote:
> > On Wed, Mar 13, 2013 at 1:57 PM, Marek Polacek <polacek@redhat.com> wrote:
> > > Ping.
> >
> > Ok. (yay, oldest patch in my review queue ...)
>
> ;) thanks. Just to be sure, did you mean to ok this patch (that is,
> the one with HOST_BITS_PER_INT)?
>
> Bootstrap/regtest in progress.
>
> 2013-12-02 Marek Polacek <polacek@redhat.com>
>
> PR middle-end/56344
> * calls.c (expand_call): Disallow passing huge arguments
> by value.
>
> --- gcc/calls.c.mp4 2013-12-02 17:12:18.621057873 +0100
> +++ gcc/calls.c 2013-12-02 17:32:35.523684716 +0100
> @@ -3047,6 +3047,15 @@ expand_call (tree exp, rtx target, int i
> {
> rtx before_arg = get_last_insn ();
>
> + /* We don't allow passing huge (> 2^30 B) arguments
> + by value. It would cause an overflow later on. */
> + if (adjusted_args_size.constant
> + >= (1 << (HOST_BITS_PER_INT - 1)))
Surely I meant to use "HOST_BITS_PER_INT - 2" here.
Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] Fix PR56344
2013-12-02 19:19 ` Marek Polacek
@ 2013-12-02 20:35 ` Richard Biener
0 siblings, 0 replies; 12+ messages in thread
From: Richard Biener @ 2013-12-02 20:35 UTC (permalink / raw)
To: Marek Polacek; +Cc: Joseph S. Myers, GCC Patches
Marek Polacek <polacek@redhat.com> wrote:
>On Mon, Dec 02, 2013 at 05:40:33PM +0100, Marek Polacek wrote:
>> On Mon, Dec 02, 2013 at 04:01:05PM +0100, Richard Biener wrote:
>> > On Wed, Mar 13, 2013 at 1:57 PM, Marek Polacek <polacek@redhat.com>
>wrote:
>> > > Ping.
>> >
>> > Ok. (yay, oldest patch in my review queue ...)
>>
>> ;) thanks. Just to be sure, did you mean to ok this patch (that is,
>> the one with HOST_BITS_PER_INT)?
Yes, thanks,
Richard.
>> Bootstrap/regtest in progress.
>>
>> 2013-12-02 Marek Polacek <polacek@redhat.com>
>>
>> PR middle-end/56344
>> * calls.c (expand_call): Disallow passing huge arguments
>> by value.
>>
>> --- gcc/calls.c.mp4 2013-12-02 17:12:18.621057873 +0100
>> +++ gcc/calls.c 2013-12-02 17:32:35.523684716 +0100
>> @@ -3047,6 +3047,15 @@ expand_call (tree exp, rtx target, int i
>> {
>> rtx before_arg = get_last_insn ();
>>
>> + /* We don't allow passing huge (> 2^30 B) arguments
>> + by value. It would cause an overflow later on. */
>> + if (adjusted_args_size.constant
>> + >= (1 << (HOST_BITS_PER_INT - 1)))
>
>Surely I meant to use "HOST_BITS_PER_INT - 2" here.
>
> Marek
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2013-12-02 20:35 UTC | newest]
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2013-02-26 18:27 [PATCH] Fix PR56344 Marek Polacek
2013-02-26 23:17 ` Joseph S. Myers
2013-02-27 9:56 ` Marek Polacek
2013-02-27 11:33 ` Richard Biener
2013-02-27 17:38 ` Joseph S. Myers
2013-03-01 8:41 ` Richard Biener
2013-03-05 16:06 ` Marek Polacek
2013-03-13 12:57 ` Marek Polacek
2013-12-02 15:01 ` Richard Biener
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2013-12-02 19:19 ` Marek Polacek
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