http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50146
Bug #: 50146
Summary: [4.7 regression] unused variable saved_nregs in
ira-color.c broke arm-linux-gnueabi bootstrap
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: bootstrap
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: mi...@it.uu.se
gcc-4.7-20110820 fails to bootstrap on arm-linux-gnueabi with:
/mnt/scratch/objdir47/./prev-gcc/xgcc -B/mnt/scratch/objdir47/./prev-gcc/
-B/mnt/scratch/install47/armv5tel-brewer-linux-gnueabi/bin/
-B/mnt/scratch/install47/armv5tel-brewer-linux-gnueabi/bin/
-B/mnt/scratch/install47/armv5tel-brewer-linux-gnueabi/lib/ -isystem
/mnt/scratch/install47/armv5tel-brewer-linux-gnueabi/include -isystem
/mnt/scratch/install47/armv5tel-brewer-linux-gnueabi/sys-include -c -g -O2
-gtoggle -DIN_GCC -W -Wall -Wwrite-strings -Wcast-qual -Wstrict-prototypes
-Wmissing-prototypes -Wmissing-format-attribute -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Werror -Wold-style-definition
-Wc++-compat -DHAVE_CONFIG_H -I. -I. -I/mnt/scratch/gcc-4.7-20110820/gcc
-I/mnt/scratch/gcc-4.7-20110820/gcc/.
-I/mnt/scratch/gcc-4.7-20110820/gcc/../include
-I/mnt/scratch/gcc-4.7-20110820/gcc/../libcpp/include
-I/home/mikpe/pkgs/linux-armv5l/gmp-4.3.2/include
-I/home/mikpe/pkgs/linux-armv5l/mpfr-2.4.2/include
-I/home/mikpe/pkgs/linux-armv5l/mpc-0.8.2/include
-I/mnt/scratch/gcc-4.7-20110820/gcc/../libdecnumber
-I/mnt/scratch/gcc-4.7-20110820/gcc/../libdecnumber/dpd -I../libdecnumber
/mnt/scratch/gcc-4.7-20110820/gcc/ira-color.c -o ira-color.o
/mnt/scratch/gcc-4.7-20110820/gcc/ira-color.c: In function 'assign_hard_reg':
/mnt/scratch/gcc-4.7-20110820/gcc/ira-color.c:1570:54: error: unused variable
'saved_nregs' [-Werror=unused-variable]
cc1: all warnings being treated as errors
make[3]: *** [ira-color.o] Error 1
make[3]: Leaving directory `/mnt/scratch/objdir47/gcc'
make[2]: *** [all-stage2-gcc] Error 2
make[2]: Leaving directory `/mnt/scratch/objdir47'
make[1]: *** [stage2-bubble] Error 2
make[1]: Leaving directory `/mnt/scratch/objdir47'
make: *** [bootstrap] Error 2
The previous weekly snapshot, gcc-4.7-20110813, bootstrapped fine.
The issue is that saved_nregs is declared unconditionally but used #ifndef
HONOR_REG_ALLOC_ORDER. The ARM backend does define HONOR_REG_ALLOC_ORDER, so
the warning is expected.
I'm testing the following fix:
--- gcc-4.7-20110820/gcc/ira-color.c.~1~ 2011-08-18 16:56:36.000000000
+0200
+++ gcc-4.7-20110820/gcc/ira-color.c 2011-08-21 19:11:00.000000000 +0200
@@ -1567,13 +1567,14 @@ static bool
assign_hard_reg (ira_allocno_t a, bool retry_p)
{
HARD_REG_SET conflicting_regs[2], profitable_hard_regs[2];
- int i, j, hard_regno, best_hard_regno, class_size, saved_nregs;
+ int i, j, hard_regno, best_hard_regno, class_size;
int cost, mem_cost, min_cost, full_cost, min_full_cost, nwords, word;
int *a_costs;
enum reg_class aclass;
enum machine_mode mode;
static int costs[FIRST_PSEUDO_REGISTER], full_costs[FIRST_PSEUDO_REGISTER];
#ifndef HONOR_REG_ALLOC_ORDER
+ int saved_nregs;
enum reg_class rclass;
int add_cost;
#endif
