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Re: fold_indirect_ref bogous


Jeffrey A Law wrote:
> On Wed, 2005-04-27 at 16:19 +0200, Richard Guenther wrote:
> 
>>fold_indirect_ref, called from the gimplifier happily converts
>>
>> const char *a;
>>
>>...
>>
>> *(char *)&a[x] = 0;
>>
>>to
>>
>> a[x] = 0;
>>
>>confusing alias1 and ICEing in verify_ssa:
>>
>>/net/alwazn/home/rguenth/src/gcc/cvs/gcc-4.1/gcc/testsuite/gcc.c-torture/execute/20031215-1.c:11:
>>error: Statement makes a memory store, but has no V_MAY_DEFS nor
>>V_MUST_DEFS
>>#   VUSE <ao_1>;
>>ao.ch[D.1242_5] = 0;
>>/net/alwazn/home/rguenth/src/gcc/cvs/gcc-4.1/gcc/testsuite/gcc.c-torture/execute/20031215-1.c:11:
>>internal compiler error: verify_ssa failed.
>>
>>happens only for patched gcc where C frontend and fold happen to
>>produce .02.original:
>>
>>;; Function test1 (test1)
>>;; enabled by -tree-original
>>
>>
>>{
>>  if (ao.ch[ao.l] != 0)
>>    {
>>      *(char *) &ao.ch[(unsigned int) ao.l] = 0;
>>    }
>>}
>>
>>then, generic is already wrong:
>>
>>test1 ()
>>{
>>  int D.1240;
>>  char D.1241;
>>  unsigned int D.1242;
>>
>>  D.1240 = ao.l;
>>  D.1241 = ao.ch[D.1240];
>>  if (D.1241 != 0)
>>    {
>>      D.1240 = ao.l;
>>      D.1242 = (unsigned int) D.1240;
>>      ao.ch[D.1242] = 0;
>>    }
>>
>>(not the missing cast).
>>
>>
>>something like the following patch fixes this.
> 
> How ironic.  I ran into a similar problem with the fold-after-TER
> patches.  I just killed the STRIP_NOPS call, but using STRIP_TYPE_NOPS
> might be a better solution.

So is the patch ok for mainline?  It happened to be in during a
bootstrap and regtest on i686-linux for c only.

Richard.


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