[Bug target/35264] New: [4.3 regression] ntfs-3g miscompiled

["matz at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

This testcase, compiled with -O1 aborts:

% cat t.c
extern void abort(void);
long long __attribute__((noinline)) get(void)
{
  return -2;
}
long long __attribute__((noinline)) get(void);
int __attribute__((noinline)) check(void)
{
 long long lcn;

 lcn = get();
 if (lcn >= 0 || lcn == -1)
  return 0;

 return -1;
}
int main()
{
  if (check() == 0)
    abort();
  return 0;
}

Reason is ix86_expand_branch, the committ for PR target/29978 misses breaks
in the switch statement, hence falls through into the wrong branch.

Obvious patch:
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c  (revision 132470)
+++ config/i386/i386.c  (working copy)
@@ -12148,6 +12152,7 @@ ix86_expand_branch (enum rtx_code code,
                  ix86_expand_branch (code, label);
                  return;
                }
+             break;
            case LE: case LEU: case GT: case GTU:
              if (lo[1] == constm1_rtx)
                {
@@ -12156,6 +12161,7 @@ ix86_expand_branch (enum rtx_code code,
                  ix86_expand_branch (code, label);
                  return;
                }
+             break;
            default:
              break;
            }

Richi already preapproved this patch for 4.3, I'm opening this PR anyway, to
have a reference for the testcase.


-- 
           Summary: [4.3 regression] ntfs-3g miscompiled
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: matz at gcc dot gnu dot org
GCC target triplet: i386


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35264