[Bug middle-end/54664] New: expand_gimple_cond warning for predictably small BRANCH_COST

["amylaar at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54664

             Bug #: 54664
           Summary: expand_gimple_cond warning for predictably small
                    BRANCH_COST
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: amylaar@gcc.gnu.org
            Blocks: 44756
            Target: pdp11-aout


g++ -c   -g -O2 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE  -fno-exceptions -fno-rtti
-W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute
-pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Werror
-fno-common  -DHAVE_CONFIG_H -I. -I. -I../../../gcc/gcc -I../../../gcc/gcc/.
-I../../../gcc/gcc/../include -I../../../gcc/gcc/../libcpp/include 
-I../../../gcc/gcc/../libdecnumber -I../../../gcc/gcc/../libdecnumber/dpd
-I../libdecnumber    ../../../gcc/gcc/cfgexpand.c -o cfgexpand.o
../../../gcc/gcc/cfgexpand.c: In function âbasic_block_def*
expand_gimple_cond(basic_block, gimple)â:
../../../gcc/gcc/cfgexpand.c:1810:65: error: comparison is always true due to
limited range of data type [-Werror=type-limits]
    else if (BRANCH_COST (optimize_insn_for_speed_p (), false) < 4)
                                                                 ^
cc1plus: all warnings being treated as errors
make[2]: *** [cfgexpand.o] Error 1

pdp11.h defines BRANCH_COST as a macro that yield either 0 or 1.

cfgexpand.c:expand_gimple_cond compares this to 4.  Because of the warning
options we use for building cfgexpand.o, we cant't build it for pdp11
configured with --emable-werror-always.