http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56023
Bug #: 56023
Summary: [4.6 Regression]: [alpha] -fcompare-debug failure due
to sched1 pass
Classification: Unclassified
Product: gcc
Version: 4.6.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ubiz...@gmail.com
Host: x86_64-linux-gnu
Target: alpha-linux-gnu
Following compare-debug failure breaks bootstrap on alpha-linux-gnu on 4.6:
--cut here--
void
foo (char *c)
{
unsigned int x = 0;
unsigned int i;
for (i = 0; c[i]; i++)
{
if (i >= 5 && x != 1)
break;
else if (c[i] == ' ')
x = i;
else if (c[i] == '/' && c[i + 1] != ' ' && i)
x = i + 1;
}
}
--cut here--
The compare-debug failure can be reproduced on a cross to alpha-linux-gnu:
~/gcc-build-alpha/gcc/xgcc -B ~/gcc-build-alpha/gcc -O2 -fcompare-debug -S t.c
xgcc: error: t.c: -fcompare-debug failure
~/gcc-build-alpha/gcc/xgcc -v
Using built-in specs.
COLLECT_GCC=/home/uros/gcc-build-alpha/gcc/xgcc
Target: alpha-linux-gnu
Configured with: ../gcc-svn/branches/gcc-4_6-branch/configure
--target=alpha-linux-gnu
Thread model: posix
gcc version 4.6.4 20130117 (prerelease) [gcc-4_6-branch revision 195276] (GCC)
The resulting assembly differs in:
--with g--
$L8:
$LM8:
cmpeq $5,1,$5 # 30 *setcc_internal [length = 4]
cmpult $8,$2,$2 # 35 *setcc_internal [length = 4]
cmpeq $5,0,$5 # 31 *setcc_internal [length = 4]
(*) addl $3,1,$3 # 43 *addsi_se/1 [length = 4]
and $5,$2,$2 # 39 anddi3/1 [length = 4]
cpys $f31,$f31,$f31 # 171 fnop [length = 4]
(**) addl $4,1,$4 # 41 *addsi_se/1 [length = 4]
bne $2,$L1 # 44 *bcc_normal [length = 4]
$L9:
--/with g--
--without g--
$L8:
cmpeq $5,1,$5 # 26 *setcc_internal [length = 4]
cmpult $8,$2,$2 # 31 *setcc_internal [length = 4]
cmpeq $5,0,$5 # 27 *setcc_internal [length = 4]
(**) addl $4,1,$4 # 37 *addsi_se/1 [length = 4]
and $5,$2,$2 # 35 anddi3/1 [length = 4]
cpys $f31,$f31,$f31 # 143 fnop [length = 4]
(*) addl $3,1,$3 # 39 *addsi_se/1 [length = 4]
bne $2,$L1 # 40 *bcc_normal [length = 4]
$L9:
--/without g--
Insns (*) and (**) switched places when compiled w/ or w/o "-g".
The problem is in sched1 pass, where the first difference occurs, and adding
-fno-schedule-insns to compile flags avoids the failure.
