[Bug bootstrap/62077] --with-build-config=bootstrap-lto fails,

venkataramanan.kumar at amd dot com gcc-bugzilla@gcc.gnu.org
Tue Aug 12 08:23:00 GMT 2014


--- Comment #11 from Venkataramanan <venkataramanan.kumar at amd dot com> ---
I am also trying to fix LTO bootstrap compare failure in Aarch64.

Bootstrap compare failure is not occurring in GCC FSF trunk (tested on aarch64
as well as x86_64 machine). Now I am doing one more round of bisecting to see
which revision fixes this (or) first time compare not seen. 

Also I tried to recompile gimple.o which was miscomparing and also dump the
gimple and IPA IR. I found that in GCC trunk there are no differences between
stage2 and stage3 dumps.

But with GCC 4.9 there are some differences, 

Stage2 (prev-gcc) vs stage3 (gcc)

Very first dump file is gimple.c.001t.tu 

The number of  @numbers are more in stage2
@103184 identifier_node  strg: debug_ready_dispatch    lngt: 20      

@103169 identifier_node  strg: debug_ready_dispatch    lngt: 20

Also gimple.c.048i.inline showed differences in Min size.


<   min size:       6
>   min size:       0
<   min size:       14
>   min size:       0
<   min size:       28

In gimple-fold.c.000i.cgraph

< _Z25gimple_build_omp_continueP9tree_nodeS0_/761
(gimple_build_omp_continue(tree_node*, tree_node*)) @0x3ff7ebda548
> _Z25gimple_build_omp_continueP9tree_nodeS0_/761 
> (gimple_build_omp_continue(tree_node*, tree_node*)) @0x3ff92b5a548

why do these dumps show differences? The other tree optimization dumps don't
show any difference.

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