[Bug target/69124] New: arm miss compiled code since gcc 5

[gcc at breakpoint dot cc]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69124

            Bug ID: 69124
           Summary: arm miss compiled code since gcc 5
           Product: gcc
           Version: 5.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc at breakpoint dot cc
  Target Milestone: ---
              Host: arm-linux-gnueabihf
            Target: arm-linux-gnueabihf
             Build: arm-linux-gnueabihf

Created attachment 37213
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37213&action=edit
test case, fp_mul_comba_32.c

Attached a testcase that miss compiles on ARM since gcc-5 (Debian gcc, built
with --with-arch=armv7-a --with-fpu=vfpv3-d16 --with-float=hard).

gcc -o fp_mul fp_mul_comba_32.c -O2 -Wall -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations

./fp_mul
27 0x0a7d8ff8 != 0xce804437
28 0x1c8a1f70 != 0x1c8a1f6f
-> 3

I don't see this with problem with -O1, or arm-linux-gnueabi target (i.e. no
output). 

The bug does not trigger with -fsanitize=undefined but it does not show any
output.