| Message ID | d774ee.38da1.14e24fd8cba.Coremail.yizhouzhou@ict.ac.cn |
|---|---|
| State | New |
| Headers | show |
On 06/24/2015 03:54 AM, Zhouyi Zhou wrote: > > In function assign_hard_reg, checking the bit of conflict_a in > consideration_allocno_bitmap is unneccesary, because when retry_p is > false, conflicting objects are always inside of the same loop_node > (this is ensured in function process_bb_node_lives which marks the > living objects to death near the end of that function). > > > > Bootstrap and regtest scheduled on x86_64 GNU/Linux > Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn> > --- > gcc/ChangeLog | 4 ++++ > gcc/ira-color.c | 6 ++---- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/gcc/ChangeLog b/gcc/ChangeLog > index d1f82b2..07605ae 100644 > --- a/gcc/ChangeLog > +++ b/gcc/ChangeLog > @@ -1,3 +1,7 @@ > +2015-06-24 Zhouyi Zhou <yizhouzhou@ict.ac.cn> > + > + * ira-color.c (assign_hard_reg): save a bitmap check My concern here is the invariant you're exploiting to eliminate the redundant bitmap check is far from obvious and there's no good way I can see to ensure that invariant remains invariant. Without some solid performance data indicating this is a notable compile-time improvement, I don't think it's a wise idea. If it does turn out that this is a noteworthy compile-time improvement, then you would need a comment before this conditional explaining in detail why we don't need to check for conflict's allocno in consideration_allocno_bitmap. Jeff
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index d1f82b2..07605ae 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,7 @@ +2015-06-24 Zhouyi Zhou <yizhouzhou@ict.ac.cn> + + * ira-color.c (assign_hard_reg): save a bitmap check + 2015-06-24 Andreas Krebbel <krebbel@linux.vnet.ibm.com> PR rtl-optimization/66306 diff --git a/gcc/ira-color.c b/gcc/ira-color.c index 6c53507..d7776d6 100644 --- a/gcc/ira-color.c +++ b/gcc/ira-color.c @@ -1733,14 +1733,12 @@ assign_hard_reg (ira_allocno_t a, bool retry_p) /* Reload can give another class so we need to check all allocnos. */ if (!retry_p - && (!bitmap_bit_p (consideration_allocno_bitmap, - ALLOCNO_NUM (conflict_a)) - || ((!ALLOCNO_ASSIGNED_P (conflict_a) + && ((!ALLOCNO_ASSIGNED_P (conflict_a) || ALLOCNO_HARD_REGNO (conflict_a) < 0) && !(hard_reg_set_intersect_p (profitable_hard_regs, ALLOCNO_COLOR_DATA - (conflict_a)->profitable_hard_regs))))) + (conflict_a)->profitable_hard_regs)))) continue; conflict_aclass = ALLOCNO_CLASS (conflict_a); ira_assert (ira_reg_classes_intersect_p
In function assign_hard_reg, checking the bit of conflict_a in consideration_allocno_bitmap is unneccesary, because when retry_p is false, conflicting objects are always inside of the same loop_node (this is ensured in function process_bb_node_lives which marks the living objects to death near the end of that function). Bootstrap and regtest scheduled on x86_64 GNU/Linux Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn> --- gcc/ChangeLog | 4 ++++ gcc/ira-color.c | 6 ++---- 2 files changed, 6 insertions(+), 4 deletions(-)