http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55142
--- Comment #21 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-07 22:11:46
UTC ---
(In reply to comment #20)
> If you compile the testcase with the unmodified compiler but without -fPIC,
> you
> get in the assembly file:
>
> movl %edx, _dl_rtld_map-1073742800(,%eax,4)
>
> I presume that's wrong, correct? Yet the RTL instruction is:
That is not wrong.
> (insn:TI 43 38 44 4 (set (mem/f:SI (zero_extend:DI (plus:SI (ashift:SI (reg:SI
> 0 ax [87])
> (const_int 2 [0x2]))
> (const:SI (plus:SI (symbol_ref:SI ("_dl_rtld_map") [flags
> 0x42] <var_decl 0x7ffff6d2b7b8 _dl_rtld_map>)
> (const_int -1073742800 [0xffffffffbffffc30])))))
> [3
> *_8+0 S4 A32])
> (reg:SI 1 dx [orig:82 dyn ] [82])) pr55142.c:32 65 {*movsi_internal}
> (expr_list:REG_DEAD (reg:SI 0 ax [87])
> (nil)))
>
> and there is a zero_extend.
(,%eax,4) generates a 0x67 address-size prefix, which zero-extends
32-bit address to 64-bit.
