[Bug go/63172] New: gccgo testcase cplx2.go execution provides incorrect answers on trunk for powerpc64, powerpc64le

[boger at us dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63172

            Bug ID: 63172
           Summary: gccgo testcase cplx2.go execution provides incorrect
                    answers on trunk for powerpc64, powerpc64le
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: go
          Assignee: ian at airs dot com
          Reporter: boger at us dot ibm.com
                CC: bergner at vnet dot ibm.com, cmang at google dot com

Built gccgo from trunk.

Testcase cplx2.go in the go testsuite fails with incorrect answers.

>From the go.log when running 'make check-gcc-go'

opcode x (+7.218935e-001-5.325444e-001i) (+7.218935e-001-5.325444e-001i)
panic: fail

goroutine 16 [running]:
main.main
       
/home/boger/gccgo.work/orig/trunk-src/gcc/testsuite/go.test/test/ken/cplx2.go:102
created by main
        /home/boger/gccgo.work/orig/trunk-src/libgo/runtime/go-main.c:42
FAIL: go.test/test/ken/cplx2.go execution,  -O2 -g

Looking at an objdump of the executable, the compiler has determined at compile
time that the values are not correct, omits the code to do the conversion and
compare and generates the printlns and panic directly.

        r64 := real(complex128(ce))
        if r64 != real(Ce) {
                println("real(complex128(ce))", r64, real(Ce))
    10001318:   30 00 9f e8     ld      r4,48(r31)
    1000131c:   28 00 7f e8     ld      r3,40(r31)
    10001320:   41 fc ff 4b     bl      10000f60
<0000005f.plt_call.__go_print_string>
    10001324:   18 00 41 e8     ld      r2,24(r1)
    10001328:   09 fc ff 4b     bl      10000f30
<0000005f.plt_call.__go_print_space>
    1000132c:   18 00 41 e8     ld      r2,24(r1)
    10001330:   90 f8 20 fc     fmr     f1,f31
    10001334:   5d fc ff 4b     bl      10000f90
<0000005f.plt_call.__go_print_double>
    10001338:   18 00 41 e8     ld      r2,24(r1)
    1000133c:   f5 fb ff 4b     bl      10000f30
<0000005f.plt_call.__go_print_space>
    10001340:   18 00 41 e8     ld      r2,24(r1)
    10001344:   90 e8 20 fc     fmr     f1,f29
    10001348:   49 fc ff 4b     bl      10000f90
<0000005f.plt_call.__go_print_double>
    1000134c:   18 00 41 e8     ld      r2,24(r1)
    10001350:   d1 fb ff 4b     bl      10000f20
<0000005f.plt_call.__go_print_nl>
    10001354:   18 00 41 e8     ld      r2,24(r1)
/home/boger/gccgo.work/orig/trunk-src/gcc/testsuite/go.test/test/ken/cplx2.go:120
                panic("fail")
    10001358:   10 00 60 38     li      r3,16
    1000135c:   f5 fb ff 4b     bl      10000f50 <0000005f.plt_call.__go_new>
    10001360:   18 00 41 e8     ld      r2,24(r1)
    10001364:   04 00 20 39     li      r9,4
    10001368:   78 1b 64 7c     mr      r4,r3
    1000136c:   00 00 e3 fb     std     r31,0(r3)
    10001370:   08 00 23 f9     std     r9,8(r3)
    10001374:   ff ff 62 3c     addis   r3,r2,-1
    10001378:   98 7c 63 38     addi    r3,r3,31896
    1000137c:   c5 fb ff 4b     bl      10000f40 <0000005f.plt_call.__go_panic>
    10001380:   18 00 41 e8     ld      r2,24(r1)