RFA: Fix isl-ast-gen-if-1.c test

RFA: Fix isl-ast-gen-if-1.c test

[Nick Clifton]

Hi Guys,

  The test file gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c file
  was generating an unexpected failure for the RX.  When I investigated
  I found that a return address on the stack was being corrupted, and I
  tracked it down to the foo() function:

    foo (int a[], int n)
    {
      int i;
      for (i = 0; i < n; i++)
        {
          if (i < 25)
            a[i] = i;
	  a[n - i] = 1;
        }
    }

  The problem is that when i is 0, the line a[n - i] writes to a[50]
  which is beyond the end of the a array.  (In the RX case it writes
  over the return address on the stack).

  The patch below fixes the problem, although it could also be solved by
  increasing the size of the a array when it is declared in main().

  OK to apply ?

Cheers
  Nick

gcc/testsuite/ChangeLog
2015-06-22  Nick Clifton  <nickc@redhat.com>

	* gcc.dg/graphite/isl-ast-gen-if-1.c (foo): Prevent writing after
	the end of the array.

Index: gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c
===================================================================
--- gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c	(revision 224722)
+++ gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c	(working copy)
@@ -10,7 +10,8 @@
     {
       if (i < 25)
         a[i] = i;
-      a[n - i] = 1;
+      if (i > 0)
+	a[n - i] = 1;
     }
 }
 

Re: RFA: Fix isl-ast-gen-if-1.c test

[Jeff Law]

On 06/22/2015 09:38 AM, Nick Clifton wrote:
> Hi Guys,
>
>    The test file gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c file
>    was generating an unexpected failure for the RX.  When I investigated
>    I found that a return address on the stack was being corrupted, and I
>    tracked it down to the foo() function:
>
>      foo (int a[], int n)
>      {
>        int i;
>        for (i = 0; i < n; i++)
>          {
>            if (i < 25)
>              a[i] = i;
> 	  a[n - i] = 1;
>          }
>      }
>
>    The problem is that when i is 0, the line a[n - i] writes to a[50]
>    which is beyond the end of the a array.  (In the RX case it writes
>    over the return address on the stack).
>
>    The patch below fixes the problem, although it could also be solved by
>    increasing the size of the a array when it is declared in main().
>
>    OK to apply ?
>
> Cheers
>    Nick
>
> gcc/testsuite/ChangeLog
> 2015-06-22  Nick Clifton  <nickc@redhat.com>
>
> 	* gcc.dg/graphite/isl-ast-gen-if-1.c (foo): Prevent writing after
> 	the end of the array.
I'd tend to prefer to change the size of the array -- adding another 
conditional in the loop may have unintended consequences that possibly 
scramble things just enough to compromise the test.

jeff

Re: RFA: Fix isl-ast-gen-if-1.c test

[Nicholas Clifton]

Hi Jeff,

> I'd tend to prefer to change the size of the array -- adding another
> conditional in the loop may have unintended consequences that possibly
> scramble things just enough to compromise the test.

Okey dokey, here is a revised version.  Is this one OK ?

Cheers
   Nick

gcc/ChangeLog

Index: 2015-06-22  Nick Clifton  <nickc@redhat.com>

	* gcc.dg/graphite/isl-ast-gen-if.c (main): Increase size of a
	array to allow a[50] to be a valid location.

gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c
===================================================================
--- gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c	(revision 224722)
+++ gcc/testsuite/gcc.dg/graphite/isl-ast-gen-if-1.c	(working copy)
@@ -28,7 +28,7 @@
  int
  main (void)
  {
-  int a[50];
+  int a[51]; /* NB This size allows foo's first iteration to write to 
a[50].  */
    foo (a, 50);
    int res = array_sum (a);
    if (res != 49)

Re: RFA: Fix isl-ast-gen-if-1.c test

[Jeff Law]

On 06/22/2015 10:07 AM, Nicholas Clifton wrote:
> Hi Jeff,
>
>> I'd tend to prefer to change the size of the array -- adding another
>> conditional in the loop may have unintended consequences that possibly
>> scramble things just enough to compromise the test.
>
> Okey dokey, here is a revised version.  Is this one OK ?
>
> Cheers
>    Nick
>
> gcc/ChangeLog
>
> Index: 2015-06-22  Nick Clifton  <nickc@redhat.com>
>
>      * gcc.dg/graphite/isl-ast-gen-if.c (main): Increase size of a
>      array to allow a[50] to be a valid location.
OK.
jeff