On 01/16/2018 01:35 PM, H.J. Lu wrote:
> On Tue, Jan 16, 2018 at 3:40 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> This patch has been used with my Spectre backport for GCC 7 for many
>> weeks and has been checked into GCC 7 branch. Should I revert it on
>> GCC 7 branch or check it into trunk?
>
> Ada build failed with this on trunk:
>
> raised STORAGE_ERROR : stack overflow or erroneous memory access
> make[5]: *** [/export/gnu/import/git/sources/gcc/gcc/ada/Make-generated.in:45:
> ada/sinfo.h] Error 1
Hello.
I know that you've already reverted the change, but it's possible to replace
struct ix86_frame &frame = cfun->machine->frame;
with:
struct ix86_frame *frame = &cfun->machine->frame;
And replace usages with point access operator (->). That would also avoid
copying.
One another question. After you switched to references, isn't the behavior of
function
ix86_expand_epilogue as it also contains write to frame struct like:
14799 /* Special care must be taken for the normal return case of a function
14800 using eh_return: the eax and edx registers are marked as saved, but
14801 not restored along this path. Adjust the save location to match.
*/
14802 if (crtl->calls_eh_return && style != 2)
14803 frame.reg_save_offset -= 2 * UNITS_PER_WORD;
Thanks for clarification.
Martin
>
> Let me revert it on gcc-7-branch.
>
> H.J.
>> H.J.
>> ---
>> When there is no need to make a copy of ix86_frame, we can use reference
>> of struct ix86_frame to avoid copy.
>>
>> * config/i386/i386.c (ix86_expand_prologue): Use reference of
>> struct ix86_frame.
>> (ix86_expand_epilogue): Likewise.
>> ---
>> gcc/config/i386/i386.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> index bfb31db8752..9eba3ffd5d6 100644
>> --- a/gcc/config/i386/i386.c
>> +++ b/gcc/config/i386/i386.c
>> @@ -13385,7 +13385,6 @@ ix86_expand_prologue (void)
>> {
>> struct machine_function *m = cfun->machine;
>> rtx insn, t;
>> - struct ix86_frame frame;
>> HOST_WIDE_INT allocate;
>> bool int_registers_saved;
>> bool sse_registers_saved;
>> @@ -13413,7 +13412,7 @@ ix86_expand_prologue (void)
>> m->fs.sp_valid = true;
>> m->fs.sp_realigned = false;
>>
>> - frame = m->frame;
>> + struct ix86_frame &frame = cfun->machine->frame;
>>
>> if (!TARGET_64BIT && ix86_function_ms_hook_prologue
>> (current_function_decl))
>> {
>> @@ -14291,7 +14290,6 @@ ix86_expand_epilogue (int style)
>> {
>> struct machine_function *m = cfun->machine;
>> struct machine_frame_state frame_state_save = m->fs;
>> - struct ix86_frame frame;
>> bool restore_regs_via_mov;
>> bool using_drap;
>> bool restore_stub_is_tail = false;
>> @@ -14304,7 +14302,7 @@ ix86_expand_epilogue (int style)
>> }
>>
>> ix86_finalize_stack_frame_flags ();
>> - frame = m->frame;
>> + struct ix86_frame &frame = cfun->machine->frame;
>>
>> m->fs.sp_realigned = stack_realign_fp;
>> m->fs.sp_valid = stack_realign_fp
>> --
>> 2.14.3
>>
>
>
>
