[PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[Marek Polacek]

As demonstrated by this test, we can crash on the assert in alloca_call_type:
gcc_assert (is_vla || warn_alloca_limit > 0);
when -Walloca-larger-than= receives an argument greater than INT_MAX.  Even
though warn_vla_limit is marked as UInteger in c.opt, those are still
represented as ints; opt-functions.awk has

202         else if (flag_set_p("UInteger", flags))
203                 return "int "
...
213         if (flag_set_p("UInteger", flags))
214                 return "int "

So 4207115063 is converted to int which is some negative value.

It's probably too late to change opt-functions.awk now, so the following
is a badn aid fix.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2017-03-02  Marek Polacek  <polacek@redhat.com>

	PR middle-end/79809
	* gimple-ssa-warn-alloca.c (pass_walloca::gate): Use HOST_WIDE_INT.
	(alloca_call_type): Likewise.

	* g++.dg/Walloca1.C: New test.

diff --git gcc/gimple-ssa-warn-alloca.c gcc/gimple-ssa-warn-alloca.c
index d553a34..dd41775 100644
--- gcc/gimple-ssa-warn-alloca.c
+++ gcc/gimple-ssa-warn-alloca.c
@@ -78,7 +78,8 @@ pass_walloca::gate (function *fun ATTRIBUTE_UNUSED)
   if (first_time_p)
     return warn_alloca != 0;
 
-  return warn_alloca_limit > 0 || warn_vla_limit > 0;
+  return ((unsigned HOST_WIDE_INT) warn_alloca_limit > 0
+	  || (unsigned HOST_WIDE_INT) warn_vla_limit > 0);
 }
 
 // Possible problematic uses of alloca.
@@ -278,8 +279,8 @@ alloca_call_type (gimple *stmt, bool is_vla, tree *invalid_casted_type)
   wide_int min, max;
   struct alloca_type_and_limit ret = alloca_type_and_limit (ALLOCA_UNBOUNDED);
 
-  gcc_assert (!is_vla || warn_vla_limit > 0);
-  gcc_assert (is_vla || warn_alloca_limit > 0);
+  gcc_assert (!is_vla || (unsigned HOST_WIDE_INT) warn_vla_limit > 0);
+  gcc_assert (is_vla || (unsigned HOST_WIDE_INT) warn_alloca_limit > 0);
 
   // Adjust warn_alloca_max_size for VLAs, by taking the underlying
   // type into account.
diff --git gcc/testsuite/g++.dg/Walloca1.C gcc/testsuite/g++.dg/Walloca1.C
index e69de29..23b97e8 100644
--- gcc/testsuite/g++.dg/Walloca1.C
+++ gcc/testsuite/g++.dg/Walloca1.C
@@ -0,0 +1,6 @@
+/* PR middle-end/79809 */
+/* { dg-do compile } */
+/* { dg-options "-Walloca-larger-than=4207115063 -Wvla-larger-than=1233877270 -O2" } */
+
+int a;
+char *b = static_cast<char *>(__builtin_alloca (a)); // { dg-warning "argument to .alloca. may be too large" }

	Marek

Re: [PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[Martin Liška]

On 03/02/2017 01:32 PM, Marek Polacek wrote:
> It's probably too late to change opt-functions.awk now, so the following
> is a badn aid fix.

Thanks for the patch, I've written this to my TODO list for new stage1.
It's bit connected to IntegerRange attribute which I would like to append
to options.

Martin

Re: [PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[Jeff Law]

On 03/02/2017 05:32 AM, Marek Polacek wrote:
> As demonstrated by this test, we can crash on the assert in alloca_call_type:
> gcc_assert (is_vla || warn_alloca_limit > 0);
> when -Walloca-larger-than= receives an argument greater than INT_MAX.  Even
> though warn_vla_limit is marked as UInteger in c.opt, those are still
> represented as ints; opt-functions.awk has
>
> 202         else if (flag_set_p("UInteger", flags))
> 203                 return "int "
> ...
> 213         if (flag_set_p("UInteger", flags))
> 214                 return "int "
>
> So 4207115063 is converted to int which is some negative value.
>
> It's probably too late to change opt-functions.awk now, so the following
> is a badn aid fix.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2017-03-02  Marek Polacek  <polacek@redhat.com>
>
> 	PR middle-end/79809
> 	* gimple-ssa-warn-alloca.c (pass_walloca::gate): Use HOST_WIDE_INT.
> 	(alloca_call_type): Likewise.
>
> 	* g++.dg/Walloca1.C: New test.
OK.
jeff

Re: [PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[Andreas Schwab]

On Mär 02 2017, Marek Polacek <polacek@redhat.com> wrote:

> diff --git gcc/testsuite/g++.dg/Walloca1.C gcc/testsuite/g++.dg/Walloca1.C
> index e69de29..23b97e8 100644
> --- gcc/testsuite/g++.dg/Walloca1.C
> +++ gcc/testsuite/g++.dg/Walloca1.C
> @@ -0,0 +1,6 @@
> +/* PR middle-end/79809 */
> +/* { dg-do compile } */
> +/* { dg-options "-Walloca-larger-than=4207115063 -Wvla-larger-than=1233877270 -O2" } */
> +
> +int a;
> +char *b = static_cast<char *>(__builtin_alloca (a)); // { dg-warning "argument to .alloca. may be too large" }

FAIL: g++.dg/Walloca1.C  -std=gnu++11  (test for warnings, line 6)
FAIL: g++.dg/Walloca1.C  -std=gnu++11 (test for excess errors)
Excess errors:
/daten/aranym/gcc/gcc-20170308/gcc/testsuite/g++.dg/Walloca1.C:6:48: warning: unbounded use of 'alloca' [-Walloca-larger-than=]

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [PATCH] Fix ICE with -Walloca-larger-than=[>INT_MAX] (PR middle-end/79809)

[Marek Polacek]

On Wed, Mar 08, 2017 at 12:30:59PM +0100, Andreas Schwab wrote:
> On Mär 02 2017, Marek Polacek <polacek@redhat.com> wrote:
> 
> > diff --git gcc/testsuite/g++.dg/Walloca1.C gcc/testsuite/g++.dg/Walloca1.C
> > index e69de29..23b97e8 100644
> > --- gcc/testsuite/g++.dg/Walloca1.C
> > +++ gcc/testsuite/g++.dg/Walloca1.C
> > @@ -0,0 +1,6 @@
> > +/* PR middle-end/79809 */
> > +/* { dg-do compile } */
> > +/* { dg-options "-Walloca-larger-than=4207115063 -Wvla-larger-than=1233877270 -O2" } */
> > +
> > +int a;
> > +char *b = static_cast<char *>(__builtin_alloca (a)); // { dg-warning "argument to .alloca. may be too large" }
> 
> FAIL: g++.dg/Walloca1.C  -std=gnu++11  (test for warnings, line 6)
> FAIL: g++.dg/Walloca1.C  -std=gnu++11 (test for excess errors)
> Excess errors:
> /daten/aranym/gcc/gcc-20170308/gcc/testsuite/g++.dg/Walloca1.C:6:48: warning: unbounded use of 'alloca' [-Walloca-larger-than=]

Ok, this should help:

2017-03-08  Marek Polacek  <polacek@redhat.com>

	* g++.dg/Walloca1.C: Adjust dg-warning.

diff --git gcc/testsuite/g++.dg/Walloca1.C gcc/testsuite/g++.dg/Walloca1.C
index 23b97e8..818c6f0 100644
--- gcc/testsuite/g++.dg/Walloca1.C
+++ gcc/testsuite/g++.dg/Walloca1.C
@@ -3,4 +3,4 @@
 /* { dg-options "-Walloca-larger-than=4207115063 -Wvla-larger-than=1233877270 -O2" } */
 
 int a;
-char *b = static_cast<char *>(__builtin_alloca (a)); // { dg-warning "argument to .alloca. may be too large" }
+char *b = static_cast<char *>(__builtin_alloca (a)); // { dg-warning "argument to .alloca. may be too large|unbounded use of" }

	Marek