On Wed, Nov 12, 2014 at 9:30 PM, Andrew Pinski <pins...@gmail.com> wrote:
> On Wed, Nov 12, 2014 at 9:25 PM, Teresa Johnson <tejohn...@google.com> wrote:
>> Added testcase. Here is the new patch:
>>
>> 2014-11-12 <tejohn...@google.com>
>>
>> gcc:
>> PR tree-optimization/63841
>> * tree.c (initializer_zerop): A constructor with no elements
>> does not zero initialize.
>
> Actually an empty constructor does zero initialize. A clobber does not.
Ok, thanks, I wasn't sure.
>
> The check you want is TREE_CLOBBER_P instead.
So in initializer_zerop, a constructor that is a TREE_CLOBBER_P would
return false, right? I will make that change and retest.
Thanks,
Teresa
>
> Thanks,
> Andrew
>
>
>>
>> gcc/testsuite:
>> * g++.dg/tree-ssa/pr63841.C: New test.
>>
>> Index: tree.c
>> ===================================================================
>> --- tree.c (revision 217190)
>> +++ tree.c (working copy)
>> @@ -10330,6 +10330,8 @@ initializer_zerop (const_tree init)
>> {
>> unsigned HOST_WIDE_INT idx;
>>
>> + if (!CONSTRUCTOR_NELTS (init))
>> + return false;
>> FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), idx, elt)
>> if (!initializer_zerop (elt))
>> return false;
>> Index: testsuite/g++.dg/tree-ssa/pr63841.C
>> ===================================================================
>> --- testsuite/g++.dg/tree-ssa/pr63841.C (revision 0)
>> +++ testsuite/g++.dg/tree-ssa/pr63841.C (working copy)
>> @@ -0,0 +1,38 @@
>> +/* { dg-do run } */
>> +/* { dg-options "-O2" } */
>> +
>> +#include <cstdio>
>> +#include <string>
>> +
>> +std::string __attribute__ ((noinline)) comp_test_write() {
>> + std::string data;
>> +
>> + for (int i = 0; i < 2; ++i) {
>> + char b = 1 >> (i * 8);
>> + data.append(&b, 1);
>> + }
>> +
>> + return data;
>> +}
>> +
>> +std::string __attribute__ ((noinline)) comp_test_write_good() {
>> + std::string data;
>> +
>> + char b;
>> + for (int i = 0; i < 2; ++i) {
>> + b = 1 >> (i * 8);
>> + data.append(&b, 1);
>> + }
>> +
>> + return data;
>> +}
>> +
>> +int main() {
>> + std::string good = comp_test_write_good();
>> + printf("expected: %hx\n", *(short*)good.c_str());
>> +
>> + std::string bad = comp_test_write();
>> + printf("got: %hx\n", *(short*)bad.c_str());
>> +
>> + return good != bad;
>> +}
>>
>> On Wed, Nov 12, 2014 at 2:17 PM, Xinliang David Li <davi...@google.com>
>> wrote:
>>> missing test case?
>>>
>>> David
>>>
>>> On Wed, Nov 12, 2014 at 2:13 PM, Teresa Johnson <tejohn...@google.com>
>>> wrote:
>>>> This patch fixes an issue where tree-strlen was incorrectly removing a
>>>> store of 0 into a string because it thought a prior CLOBBER (which is
>>>> an empty constructor with no elements) was zero-initializing the
>>>> string.
>>>>
>>>> Bootstrapped and tested on x86_64-unknown-linux-gnu. OK for trunk?
>>>>
>>>> Thanks,
>>>> Teresa
>>>>
>>>> 2014-11-12 <tejohn...@google.com>
>>>>
>>>> PR tree-optimization/63841
>>>> * tree.c (initializer_zerop): A constructor with no elements
>>>> does not zero initialize.
>>>>
>>>> Index: tree.c
>>>> ===================================================================
>>>> --- tree.c (revision 217190)
>>>> +++ tree.c (working copy)
>>>> @@ -10330,6 +10330,8 @@ initializer_zerop (const_tree init)
>>>> {
>>>> unsigned HOST_WIDE_INT idx;
>>>>
>>>> + if (!CONSTRUCTOR_NELTS (init))
>>>> + return false;
>>>> FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), idx, elt)
>>>> if (!initializer_zerop (elt))
>>>> return false;
>>>>
>>>>
>>>> --
>>>> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
>>
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
