I normally run nightly spec cpu2000 benchmark testing with main line GCC. I've
seen few performance drops since July 29 2005. Currently I'm analysing
197.parser benchmark which had 15 points drop since the previous run on 28th
July. I've located following two patches
1) http://gcc.gnu.org/ml/gcc-cvs/2005-07/msg01016.html - 8 point drop
2) http://gcc.gnu.org/ml/gcc-cvs/2005-07/msg01034.html - 7 point drop
and verified that these patches have caused the drop. After looking at the 1st
patch, I found that the new assignment statement (node->global.estimated_growth
= INT_MIN) in function update_caller_keys made the difference. The rest of the
patch didn't matter. I've not studied the 2nd patch yet.
With only first patch applied, I found four (4) of the object files in
197.parser benchmark are different in code fragment and size compare to one
without the patch.
Those files are as follows,
post-process.o: +260 bytes with patch compare to without patch
prune.o: -672 bytes with patch
read-dict.o : -336 bytes with patch
utilities.o : +80 bytes
Following is the difference of object code fragment of post-process.o with and
without patch.
WITH THE PATCH WITHOUT PATCH
<post_process>: <post_process>:
mflr r3 mflr r3
stwu r1,-576(r1) stwu r1,-576(r1)
lis r9,0 lis r9,0
stw r3,580(r1) stw r3,580(r1)
stw r18,520(r1) stw r18,520(r1)
stw r19,524(r1) stw r19,524(r1)
stw r20,528(r1) stw r20,528(r1)
stw r21,532(r1) stw r21,532(r1)
stw r22,536(r1) stw r22,536(r1)
stw r23,540(r1) stw r23,540(r1)
stw r24,544(r1) stw r24,544(r1)
stw r25,548(r1) stw r25,548(r1)
stw r26,552(r1) stw r26,552(r1)
stw r27,556(r1) stw r27,556(r1)
stw r28,560(r1) stw r28,560(r1)
stw r29,564(r1) stw r29,564(r1)
stw r30,568(r1) stw r30,568(r1)
stw r31,572(r1) stw r31,572(r1)
lwz r0,0(r9) lwz r0,0(r9)
cmpwi cr7,r0,0 cmpwi cr7,r0,0
bne- cr7,5a9c <post_process+0x1ec> bne- cr7,5a9c <post_process+0x1ec>
lis r29,0 lis r29,0
li r3,8 li r3,8
bl 590c <post_process+0x5c> bl 590c <post_process+0x5c>
lwz r4,0(r29) lwz r4,0(r29)
mr r22,r3 | mr r23,r3
rlwinm r3,r4,2,0,29 rlwinm r3,r4,2,0,29
bl 591c <post_process+0x6c> bl 591c <post_process+0x6c>
lwz r11,0(r29) lwz r11,0(r29)
stw r3,0(r22) | stw r3,0(r23)
cmpwi r11,0 cmpwi r11,0
ble- 5a48 <post_process+0x198> ble- 5a48
<post_process+0x198>
li r31,1 li r31,1
li r30,0 li r30,0
addi r10,r11,-1 addi r10,r11,-1
cmpw cr6,r31,r11 | cmpw cr1,r31,r11
stw r30,0(r3) stw r30,0(r3)
clrlwi r0,r10,29 clrlwi r0,r10,29
beq- cr6,5a48 <post_process+0x198> | beq- cr1,5a48
<post_process+0x198>
cmpwi cr7,r0,0 | cmpwi r0,0
beq- cr7,59dc <post_process+0x12c> | beq- 59dc
<post_process+0x12c>
cmpwi r0,1 | cmpwi cr7,r0,1
beq- 59c8 <post_process+0x118> | beq- cr7,59c8
<post_process+0x118>
cmpwi cr1,r0,2 | cmpwi cr6,r0,2
beq- cr1,59bc <post_process+0x10c> | beq- cr6,59bc
<post_process+0x10c>
cmpwi cr6,r0,3 | cmpwi cr1,r0,3
beq- cr6,59b0 <post_process+0x100> | beq- cr1,59b0
<post_process+0x100>
cmpwi cr7,r0,4 | cmpwi r0,4
beq- cr7,59a4 <post_process+0xf4> | beq- 59a4 <post_process+0xf4>
stw r30,4(r3) stw r30,4(r3)
li r31,2 li r31,2
rlwinm r21,r31,2,0,29 | rlwinm r22,r31,2,0,29
addi r31,r31,1 addi r31,r31,1
stwx r30,r21,r3 | stwx r30,r22,r3
rlwinm r19,r31,2,0,29 | rlwinm r18,r31,2,0,29
addi r31,r31,1 addi r31,r31,1
I've lot more data. I've also taken the dump with -fdump-ipa-cgraph of the
benchmark with and without patch. I'll add it later if need it.
Thanks.
--
Summary: 197.parser performance drop
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: uttamp at us dot ibm dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: powerpc-linux
GCC host triplet: powerpc-linux
GCC target triplet: powerpc-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23785
