[Bug debug/48333] New: -fcompare-debug failure (length) - "memmove" x "__builtin_memmove"

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48333

           Summary: -fcompare-debug failure (length) - "memmove" x
                    "__builtin_memmove"
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
                CC: aoliva@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23798
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23798
partially reduced testcase

Compiler output:
$ gcc -O -fkeep-inline-functions -fcompare-debug testcase.ii 
testcase.ii: In function âstd::_Resetiosflags
std::resetiosflags(std::ios_base::fmtflags)â:
testcase.ii:20948:5: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
testcase.ii: In function âstd::_Setiosflags
std::setiosflags(std::ios_base::fmtflags)â:
testcase.ii:20966:5: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
testcase.ii: In function âstd::_Setbase std::setbase(int)â:
testcase.ii:20984:5: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
testcase.ii: In function âstd::_Setfill<_CharT> std::setfill(_CharT)â:
testcase.ii:21010:7: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
testcase.ii: In function âstd::_Setprecision std::setprecision(int)â:
testcase.ii:21028:5: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
testcase.ii: In function âstd::_Setw std::setw(int)â:
testcase.ii:21046:5: warning: extended initializer lists only available with
-std=c++0x or -std=gnu++0x [enabled by default]
gcc: error: testcase.ii: -fcompare-debug failure (length)

$ diff testcase.*gkd
24071c24071
<         (call (mem:QI (symbol_ref:DI ("memmove") [flags 0x41]  <function_decl
# memmove>) [ memmove S1 A8])
---
>         (call (mem:QI (symbol_ref:DI ("memmove") [flags 0x41]  <function_decl # memmove>) [ __builtin_memmove S1 A8])

Reducing the testcase is very slow. I met this problem several times, but never
with a small testcase.