[Bug bootstrap/71399] GCC 5.3.0 bootstrap comparison failure on arm-linux-gnueabihf

[ludo at gnu dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71399

--- Comment #5 from Ludovic Courtès <ludo at gnu dot org> ---
I tried this time with GCC 5.4.0, and with BOOT_CFLAGS='-O2 -g0 -da'.  I'm also
getting the failure:

  make[3]: Leaving directory '/tmp/guix-build-gcc-5.4.0.drv-0/build'
  Comparing stages 2 and 3
  warning: gcc/cc1plus-checksum.o differs
  warning: gcc/cc1-checksum.o differs
  Bootstrap comparison failure!
  gcc/c/c-parser.o differs
  gcc/c/c-typeck.o differs
  gcc/cp/semantics.o differs
  gcc/cp/optimize.o differs
  gcc/c-family/cilk.o differs
  gcc/coverage.o differs
  gcc/df-scan.o differs
  gcc/double-int.o differs
  gcc/dwarf2cfi.o differs
  gcc/fold-const.o differs
  gcc/ipa-inline.o differs
  gcc/omp-low.o differs
  gcc/real.o differs
  gcc/simplify-rtx.o differs
  gcc/tree-dfa.o differs
  gcc/tree-nested.o differs
  gcc/tree-inline.o differs
  gcc/tree-switch-conversion.o differs
  gcc/tree-ssa-math-opts.o differs
  gcc/tree-ssa-sccvn.o differs
  gcc/gcov-dump.o differs
  gcc/libgcov-driver-tool.o differs
  libiberty/simple-object-xcoff.o differs
  libiberty/fibheap.o differs
  libiberty/sort.o differs
  libiberty/pic/simple-object-xcoff.o differs
  libiberty/pic/fibheap.o differs
  libiberty/pic/sort.o differs
  Makefile:21400: recipe for target 'compare' failed
  make[2]: *** [compare] Error 1
  make[2]: Leaving directory '/tmp/guix-build-gcc-5.4.0.drv-0/build'

I have attached the diff of stage[23]-gcc/real.c.192r.expand in the hope it
would provide useful info.  I have hundreds of GiBs of RTL dumps to share, so
let me know what you'd like to see!  :-)