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Re: help with PR69133
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Prathamesh Kulkarni <prathamesh dot kulkarni at linaro dot org>, Jan Hubicka <hubicka at ucw dot cz>
- Cc: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Kugan Vivekanandarajah <kugan dot vivekanandarajah at linaro dot org>
- Date: Mon, 18 Jan 2016 10:32:52 +0100
- Subject: Re: help with PR69133
- Authentication-results: sourceware.org; auth=none
- References: <CAAgBjM=gA7=Z8H=koZhX0kuxi+aAVp1ZLik=50cYZkv_GzJzdQ at mail dot gmail dot com> <CAAgBjMnJJSdZKLVxrsM6_bXkdq50kobZbBf+dzErCDiuJdbvuA at mail dot gmail dot com>
On Mon, Jan 18, 2016 at 10:28 AM, Prathamesh Kulkarni
<prathamesh.kulkarni@linaro.org> wrote:
> On 17 January 2016 at 14:56, Prathamesh Kulkarni
> <prathamesh.kulkarni@linaro.org> wrote:
>> Hi,
>> I was having a look at PR69133.
>> It appears that with -flto-partition=none,
>> cgraph_node::get_untransformed_body ()
>> is called twice for node with asm_name _ZThn4_N11xercesc_3_11C5m_fn6ERKi.
>> c++filt says it is: non-virtual thunk to xercesc_3_1::C::m_fn6(int const&)
>>
>> get_untransformed_body() calls
>> lto_free_function_in_decl_state_for_node() which sets
>> node->lto_file_data to NULL.
>> Now 2nd time get_untransformed_body is called for the same node,
>> node->lto_file_data is NULL and lto_get_decl_name_mapping() dereferences
>> lto_file_data which results in segfault.
>>
>> I was wondering if gating on lto_file_data could be a reasonable solution ?
>> if (!lto_file_data)
>> return false;
>> I am not sure what value to return for this case (I chose false
>> because of early exit).
>> It prevents the ICE, and the patch passes bootstrap+test on
>> x86_64-unknown-linux-gnu.
>> With partitoning enabled, for the above test-case,
>> get_untransformed_body () is called only once per node. However I
>> don't understand why it gets called twice with -flto-partition=none.
> Kugan pointed out to me the test-case doesn't ICE by passing -fno-ipa-icf.
It looks to me we are not supposed to call this twice on the same node
but nothing guards against that (and we don't release the untransformed
body either). -flto-partition=none is special here becaue it combines WPA
and late stage. IPA ICF is the only IPA pass needing untransformed bodies
during WPA.
Richard.
> Thanks,
> Prathamesh
>>
>> Thank you,
>> Prathamesh