On Sat, Jul 9, 2011 at 3:46 PM, Richard Henderson <r...@redhat.com> wrote:
> On 07/09/2011 02:41 PM, H.J. Lu wrote:
>> Hi,
>>
>> X32 uses movl instead of movabs for trampoline. OK for trunk?
>>
>> Thanks.
>>
>> H.J.
>> ---
>> 2011-07-09 H.J. Lu <hongjiu...@intel.com>
>>
>> * config/i386/i386.c (ix86_trampoline_init): Use movl instead
>> of movabs for x32.
>>
>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> index 04cb07d..c852719 100644
>> --- a/gcc/config/i386/i386.c
>> +++ b/gcc/config/i386/i386.c
>> @@ -22721,13 +23030,14 @@ ix86_trampoline_init (rtx m_tramp, tree fndecl,
>> rtx chain_value)
>> }
>> else
>> {
>> - int offset = 0;
>> + int offset = 0, size;
>>
>> /* Load the function address to r11. Try to load address using
>> the shorter movl instead of movabs. We may want to support
>> movq for kernel mode, but kernel does not use trampolines at
>> the moment. */
>> - if (x86_64_zext_immediate_operand (fnaddr, VOIDmode))
>> + if (TARGET_X32
>> + || x86_64_zext_immediate_operand (fnaddr, VOIDmode))
>
> Is this change actually necessary? I would think that the
> predicate has already been adjusted...
>
>> - emit_move_insn (mem, gen_int_mode (0xba49, HImode));
>> + /* Use the shorter movl instead of movabs for x32. */
>> + if (TARGET_X32)
>> + {
>> + size = 6;
>> + emit_move_insn (mem, gen_int_mode (0xba41, HImode));
>
> Have I forgotten x86 encoding? I thought movl imm,reg was 5 bytes...
>
>
You forgot the REX prefix:
[hjl@gnu-6 tmp]$ cat x.s
mov $0x12340000, %r11d
[hjl@gnu-6 tmp]$ gcc -c x.s
[hjl@gnu-6 tmp]$ objdump -dw x.o
x.o: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <.text>:
0: 41 bb 00 00 34 12 mov $0x12340000,%r11d
[hjl@gnu-6 tmp]$
--
H.J.
