https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61969
Bug ID: 61969
Summary: wrong code by LTO on x86_64-linux-gnu (affecting
trunk, 4.9.x, and 4.8.x)
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Created attachment 33217
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33217&action=edit
test files and compilation script
The current gcc trunk (as well as gcc 4.8.x and 4.9.x) miscompiles the attached
code when using LTO on x86_64-linux-gnu in 64-bit mode (but not in 32-bit
mode).
This is a regression from 4.7.x.
Sorry that the test case is still pretty complex. It seems very difficult to be
reduced further --- any small changes to the code seem to hide the bug.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.10.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.10.0 20140730 (experimental) [trunk revision 213231] (GCC)
$
$ compile.sh
Usage: ./compile.sh <cc> <mode> <lto: 1 | 0>
$ compile.sh gcc-trunk 64 0; t
-25246
$ compile.sh gcc-trunk 64 1; t
-25246
$ compile.sh gcc-trunk 32 0; t
-25246
$ compile.sh gcc-trunk 32 1; t
0
$ compile.sh gcc-4.9 32 1; t
0
$ compile.sh gcc-4.8 32 1; t
2052
$ compile.sh gcc-4.7 32 1; t
-25246
$
