On 10/10/13 18:41, Jeff Law wrote:
> On 10/10/13 04:00, Andreas Krebbel wrote:
>> On 09/10/13 21:46, Jeff Law wrote:
>>> On 08/21/13 03:21, Andreas Krebbel wrote:
>>>> [RFC] Allow functions calling mcount before prologue to be leaf functions
>>>> http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00993.html
>>> I don't think this is necessarily correct for all targets. ISTM the
>>> ability to consider a function calling mcount as a leaf needs to be a
>>> property of the target.
>>
>> We have already "profile_before_prologue" as a target property. Shouldn't
>> this be enough to decide
>> upon this? When a function calls mcount before the prologue it shouldn't
>> matter whether the function
>> is leaf or not.
> I don't think so, I think it'd break the PA's 32 bit ABI, maybe the 64
> bit ABI as well. It's the caller's responsibility to build a mini stack
> frame if the function makes any calls. If the code in the prologue
> expander uses "leafness" to make the decision about whether or not to
> allocate the mini frame, then it'd do the wrong thing here.
Since it seems to be about PROFILE_HOOKS vs FUNCTION_PROFILER targets what
about the following patch:
Index: gcc/final.c
===================================================================
*** gcc/final.c.orig 2013-10-11 18:51:53.928452672 +0200
--- gcc/final.c 2013-10-11 18:56:20.761359142 +0200
*************** leaf_function_p (void)
*** 4237,4244 ****
{
rtx insn;
! if (crtl->profile || profile_arc_flag)
return 0;
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
--- 4237,4253 ----
{
rtx insn;
! #ifdef PROFILE_HOOK
! /* PROFILE_HOOK emits code always after prologue. */
! if (crtl->profile)
return 0;
+ #else
+ /* This is for targets using the FUNCTION_PROFILER hook. If the
+ code is emitted before prologue the function might still be a
+ leaf function. */
+ if (!targetm.profile_before_prologue () && crtl->profile)
+ return 0;
+ #endif
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
I've verified with a cross that on hppa target nothing changes when using -pg.
Bye,
-Andreas-
