[Bug lto/65130] New: ICE with LTO on valid code on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65130

            Bug ID: 65130
           Summary: ICE with LTO on valid code on x86_64-linux-gnu
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The following code causes an ICE when compiled with the current gcc trunk with
LTO on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It is a regression from 4.9.x.

$ 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/5.0.0/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 5.0.0 20150219 (experimental) [trunk revision 220822] (GCC) 
$ 
$ gcc-4.9 -flto -O1 -c foo.c
$ gcc-4.9 -flto -O2 -c main.c
$ gcc-4.9 -flto -O1 foo.o main.o
$ ./a.out
$ 
$ gcc-trunk -flto -O1 -c foo.c
$ gcc-trunk -flto -O2 -c main.c
$ gcc-trunk -flto -O1 foo.o main.o
gcc-trunk: internal compiler error: Segmentation fault (program lto1)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
lto-wrapper: fatal error: gcc-trunk returned 4 exit status
compilation terminated.
/usr/bin/ld: lto-wrapper failed
collect2: error: ld returned 1 exit status
$ 
$ cat foo.c
extern void fn3 (void); 

void fn2(void) 
{ 
  fn3(); 
}

void fn1(void) 
{ 
  fn2(); 
}

void fn4(void) 
{ 
  fn2(); 
}
$ cat main.c
extern void fn1(void);
extern void fn4 (void); 

int a; 

void fn3(void) 
{
  for (; a;)
    fn4();
}

int main() {
  fn1();
  return 0;
}
$