[Bug rtl-optimization/46391] false dependencies are computed after vectorization (#2)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46391
--- Comment #3 from Roy Rosen roy.1rosen at gmail dot com 2010-11-11 08:03:57
UTC ---
It happens also on i386 with ./cc1 -O3 a.c -fdump-rtl-all -funroll-loops
-fsched-verbose=8 -fschedule-insns:
In asmcons:
(insn 16 15 17 4 a.c:5 (set (reg:SI 72 [ vect_var_.26 ])
(mem:SI (plus:SI (reg/v/f:SI 74 [ c ])
(reg:SI 70 [ ivtmp.42 ])) [0 MEM[(char * restrict)vect_p.22]+0
S4 A32])) 50 {*movsi_internal} (nil))
(insn 17 16 134 4 a.c:5 (set (mem:SI (plus:SI (reg/v/f:SI 75 [ d ])
(reg:SI 70 [ ivtmp.42 ])) [0 MEM[(char * restrict)vect_p.27]+0
S4 A32])
(reg:SI 72 [ vect_var_.26 ])) 50 {*movsi_internal} (expr_list:REG_DEAD
(reg:SI 72 [ vect_var_.26 ])
(nil)))
(insn 134 17 135 4 a.c:5 (set (reg:SI 82 [ vect_var_.26 ])
(mem:SI (plus:SI (plus:SI (reg/v/f:SI 74 [ c ])
(reg:SI 70 [ ivtmp.42 ]))
(const_int 4 [0x4])) [0 MEM[(char * restrict)vect_p.22]+0 S4
A32])) 50 {*movsi_internal} (nil))
and in sched1:
;; ==
;; -- basic block 4 from 16 to 198 -- before reload
;; ==
;; --- forward dependences:
;; --- Region Dependences --- b 4 bb 0
;; insn codebb dep prio cost reservation
;; -- --- ---
;; 1650 4 035 4 decodern,p2: 198 196 195 185
175 165 155 145 135 17
;; 1750 4 131 1 decoder0,(p4+p3): 198 196 194
184 174 164 154 144 134
;; 13450 4 131 4 decodern,p2: 198 196 195 185
175 165 155 145 135
;; 13550 4 227 1 decoder0,(p4+p3): 198 196 194
184 174 164 154 144
There should not be any dependency between 17 (store) and 134 (load).
BTW, I failed building i386 from the current snapshot so I used an old one.
(../../gcc-4.6-20101106/gcc/config/i386/bdver1.md:528: unknown mode `V4DF'
../../gcc-4.6-20101106/gcc/config/i386/bdver1.md:528: following context is `0
r egister_operand)'
)
[Bug rtl-optimization/46391] false dependencies are computed after vectorization (#2)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46391
--- Comment #2 from Roy Rosen roy.1rosen at gmail dot com 2010-11-09 13:48:15
UTC ---
Seems to me that also on ia64 it is there but the dependecies are still wrong:
;; Function nor (nor)
nor (char * restrict c, char * restrict d)
{
long unsigned int D.2085;
long unsigned int D.2086;
vector(8) char * restrict D.2087;
void * D.2084;
long unsigned int ivtmp?52;
void * D.2071;
void * D.2070;
long unsigned int ivtmp?41;
long unsigned int ivtmp?38;
vector(8) char vect_var_?25;
long int andmask?20;
long int orptrs1?19;
long int addr2int1?18;
long int addr2int0?14;
int i;
char D.2021;
bb 2:
addr2int0?14_22 = (long int) c_8(D);
addr2int1?18_24 = (long int) d_5(D);
orptrs1?19_25 = addr2int1?18_24 | addr2int0?14_22;
andmask?20_26 = orptrs1?19_25 7;
if (andmask?20_26 == 0)
goto bb 3;
else
goto bb 5;
bb 3:
ivtmp?52_37 = (long unsigned int) c_8(D);
D.2085_32 = (long unsigned int) d_5(D);
D.2086_48 = D.2085_32 + 256;
D.2087_49 = (vector(8) char * restrict) D.2086_48;
bb 4:
# PT = nonlocal { PARM_RESTRICT?1 } (restr)
# ALIGN = 8, MISALIGN = 0
# d_43 = PHI d_44(4), d_5(D)(3)
# ivtmp?52_31 = PHI ivtmp?52_30(4), ivtmp?52_37(3)
# PT = nonlocal { PARM_RESTRICT?0 } (restr)
# ALIGN = 8, MISALIGN = 0
D.2084_33 = (void *) ivtmp?52_31;
vect_var_?25_41 = MEM[(char *)D.2084_33];
ivtmp?52_30 = ivtmp?52_31 + 8;
MEM[(char *)d_43] = vect_var_?25_41;
# PT = nonlocal { PARM_RESTRICT?1 } (restr)
d_44 = d_43 + 8;
if (d_44 != D.2087_49)
goto bb 4;
else
goto bb 7;
bb 5:
ivtmp?38_4 = (long unsigned int) c_8(D);
ivtmp?41_10 = (long unsigned int) d_5(D);
bb 6:
# i_28 = PHI 0(5), i_36(6)
# ivtmp?38_19 = PHI ivtmp?38_4(5), ivtmp?38_17(6)
# ivtmp?41_6 = PHI ivtmp?41_10(5), ivtmp?41_9(6)
# PT = nonlocal { PARM_RESTRICT?0 } (restr)
D.2070_11 = (void *) ivtmp?38_19;
D.2021_34 = MEM[(char *)D.2070_11];
ivtmp?38_17 = ivtmp?38_19 + 1;
# PT = nonlocal { PARM_RESTRICT?1 } (restr)
D.2071_13 = (void *) ivtmp?41_6;
MEM[(char *)D.2071_13] = D.2021_34;
ivtmp?41_9 = ivtmp?41_6 + 1;
i_36 = i_28 + 1;
if (i_36 != 256)
goto bb 6;
else
goto bb 7;
bb 7:
return 0;
}
[Bug rtl-optimization/46391] New: false dependencies are computed after vectorization (#2)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46391
Summary: false dependencies are computed after vectorization
(#2)
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: roy.1ro...@gmail.com
Created attachment 22343
-- http://gcc.gnu.org/bugzilla/attachment.cgi?id=22343
preprocessed file
When compiling function with ia64:
int nor(char* __restrict__ c, char* __restrict__ d)
{
int i, sum = 0;
for (i = 0; i 256; i++)
d[i] = c[i];
return sum;
}
before sched1 we have:
(insn 91 329 330 4 (set (mem:V8QI (reg/v/f:DI 435 [ d ]) [0 MEM[(char *)d_43]+0
S8 A64])
(reg:V8QI 430 [ vect_var_?25 ])) a.c:5 384 {*movv8qi_internal}
(expr_list:REG_DEAD (reg:V8QI 430 [ vect_var_?25 ])
(nil)))
(insn 330 91 253 4 (set (reg/f:DI 450)
(plus:DI (reg/v/f:DI 435 [ d ])
(const_int 8 [0x8]))) a.c:5 205 {adddi3}
(nil))
(insn 253 330 254 4 (set (reg:V8QI 455 [ vect_var_?25 ])
(mem:V8QI (reg:DI 449) [0 MEM[(char *)D.2084_33]+0 S8 A64])) a.c:5 384
{*movv8qi_internal}
(nil))
insn 91 is a store and 253 is a load from a different location (two different
restrict pointers). These insns should not have a dependency between them but
we can see in sched1 that they do have:
;; ==
;; -- basic block 4 from 89 to 340 -- before reload
;; ==
;; --- forward dependences:
;; --- Region Dependences --- b 4 bb 0
;; insn codebb dep prio cost reservation
;; -- --- ---
;; 89 384 4 0 1 1 2_M_only_um01: 340 321 320 310
299 288 277 266 255 91
;; 329 205 4 0 3 1 2_A: 340 320 254 253
;; 91 384 4 1 0 1 2_M_only_um23: 340 322 321 319
310 308 299 297 288 286 277 275 266 264 255 253
;; 330 205 4 0 2 1 2_A: 340 322 256 255
;; 253 384 4 2 1 1 2_M_only_um01: 340 321 310 299
288 277 266 255
;; 254 205 4 1 2 1 2_A: 340 264
;; 255 384 4 4 0 1 2_M_only_um23: 340 321 319 310
308 299 297 288 286 277 275 266 264
A similar bug was fixed a few months ago
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44479). Might be connected.
Using built-in specs.
COLLECT_GCC=./xgcc
Target: ia64-linux-elf
Configured with:
Thread model: single
gcc version 4.6.0 20101106 (experimental) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-funroll-loops' '-fdump-rtl-all'
'-fsched-verbose=8'
cc1 -E -quiet -v -iprefix
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/ia64-linux-elf/4.6.0/ a.c
-funroll-loops -fdump-rtl-all -fsched-verbose=8 -O3 -fpch-preprocess -o a.i
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/ia64-linux-elf/4.6.0/include
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/ia64-linux-elf/4.6.0/include-fixed
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/ia64-linux-elf/4.6.0/../../../../ia64-linux-elf/sys-include
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/ia64-linux-elf/4.6.0/../../../../ia64-linux-elf/include
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/../../lib/gcc/ia64-linux-elf/4.6.0/include
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/../../lib/gcc/ia64-linux-elf/4.6.0/include-fixed
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/../../lib/gcc/ia64-linux-elf/4.6.0/../../../../ia64-linux-elf/sys-include
ignoring nonexistent directory
/home/swproj/sw/users/eyalhar/ia64-new/gcc/../lib/gcc/../../lib/gcc/ia64-linux-elf/4.6.0/../../../../ia64-linux-elf/include
#include ... search starts here:
#include ... search starts here:
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-funroll-loops' '-fdump-rtl-all'
'-fsched-verbose=8'
cc1 -fpreprocessed a.i -quiet -dumpbase a.c -auxbase a -O3 -version
-funroll-loops -fdump-rtl-all -fsched-verbose=8 -o a.s
GNU C (GCC) version 4.6.0 20101106 (experimental) (ia64-linux-elf)
compiled by GNU C version 4.1.2 20080704 (Red Hat 4.1.2-44), GMP
version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU C (GCC) version 4.6.0 20101106 (experimental) (ia64-linux-elf)
compiled by GNU C version 4.1.2 20080704 (Red Hat 4.1.2-44), GMP
version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum:
