[Bug rtl-optimization/48334] New: [4.7 Regression] gcc.target/i386/pr39445.c FAILs with -fira-algorithm=priority

["zsojka at seznam dot cz" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48334

           Summary: [4.7 Regression] gcc.target/i386/pr39445.c FAILs with
                    -fira-algorithm=priority
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23802
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23802
reduced testcase

Output:
$ gcc -O -fira-algorithm=priority testcase.c
$ ./a.out 
Program received signal SIGSEGV, Segmentation fault.
0x0000000000400537 in foo (a1=<value optimized out>, a2=..., a3=..., a4=...,
a5=..., a6=..., a7=..., a8=..., b1=1, b2=2, b3=3, b4=4, b5=5, 
    b6=6, b7=-1, y=...) at testcase.c:8
8       {
(gdb) disassemble
Dump of assembler code for function foo:
   0x0000000000400534 <+0>:     xorps  %xmm0,%xmm0
=> 0x0000000000400537 <+3>:     movaps %xmm0,0x10(%rsp)
   0x000000000040053c <+8>:     movlps 0x10(%rsp),%xmm0
   0x0000000000400541 <+13>:    movlps %xmm0,0x10(%rsp)
   0x0000000000400546 <+18>:    movlps 0x18(%rsp),%xmm0
   0x000000000040054b <+23>:    movlps %xmm0,0x18(%rsp)
   0x0000000000400550 <+28>:    movaps 0x10(%rsp),%xmm0
   0x0000000000400555 <+33>:    retq   
End of assembler dump.
(gdb) i r rsp
rsp            0x7fffffffde28   0x7fffffffde28

The problem is unaligned access.
As in PR48331, the code generated by priority allocator is much worse than with
CB's one. The code with both allocators was the same in r171626.