[Bug middle-end/66253] New: [6 Regression] 459.GemsFDTD in SPEC CPU 2006 is miscompiled

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66253

            Bug ID: 66253
           Summary: [6 Regression] 459.GemsFDTD in SPEC CPU 2006 is
                    miscompiled
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

On Linux/x86-64, 459.GemsFDTD in SPEC CPU 2006 is miscompiled:

gfortran  -O3 -funroll-loops -ffast-math   -DSPEC_CPU_LP64        errorcheck.o
parameter.o globalvar.o excite.o fourier_transf.o huygens.fppized.o posvector.o
NFT.fppized.o readline.o PEC.o UPML.fppized.o calcflops.o progress.o
update.fppized.o leapfrog.o readdata.o GemsFDTD.o timerRoutine.o               
     -o GemsFDTD

Running Benchmarks
  Running 459.GemsFDTD ref peak lnx32e-gcc default

*** Miscompare of sphere_td.nft; for details see

r223425 is OK and r223491 is bad.