http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47727
--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-02-14 03:53:52 UTC --- cse1 generates: ;; Succ edge EXIT [100.0%] (fallthru) ;; Insn is not within a basic block (insn 63 57 64 (set (reg:SI 100) (symbol_ref:SI ("__CTOR_END__") [flags 0x2] <var_decl 0x7ffff0ced000 __CTOR_END__>)) -1 (nil)) ;; Insn is not within a basic block (insn 64 63 65 (parallel [ (set (reg:SI 99) (plus:SI (reg:SI 100) (const_int -4 [0xfffffffffffffffc]))) (clobber (reg:CC 17 flags)) ]) -1 (nil)) ;; Insn is not within a basic block (insn 65 64 0 (set (reg:DI 98) (zero_extend:DI (reg:SI 99))) -1 (nil)) This may lead to the DF problem.