[Bug tree-optimization/67305] New: [6 Regression] gcc.c-torture/compile/20121027-1.c ICE

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67305

            Bug ID: 67305
           Summary: [6 Regression] gcc.c-torture/compile/20121027-1.c ICE
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jiwang at gcc dot gnu.org
                CC: vmakarov at redhat dot com
  Target Milestone: ---
            Target: arm-none-eabi

since r226850, seen on arm-none-eabi only currently.

it can be easily reproduced by the following command. -mfpu and -mfloat are
necessary.

./cc1 -O3 -nostdinc 20121027-1.c  -march=armv8-a -mthumb
-mfpu=crypto-neon-fp-armv8 -mfloat-abi=hard

cross cc1 is generated from
   ../gcc/configure --target=arm-none-eabi --enable-languages=c,c++


t.c:13:1: internal compiler error: in decompose_normal_address, at 
rtlanal.c:6090
 }
 ^
0xc94a37 decompose_normal_address
        /space/rguenther/tramp3d/trunk/gcc/rtlanal.c:6090
0xc94d25 decompose_address(address_info*, rtx_def**, machine_mode, 
unsigned char, rtx_code)
        /space/rguenther/tramp3d/trunk/gcc/rtlanal.c:6167
0xc94dc3 decompose_mem_address(address_info*, rtx_def*)
        /space/rguenther/tramp3d/trunk/gcc/rtlanal.c:6187
0xb61149 process_address_1
        /space/rguenther/tramp3d/trunk/gcc/lra-constraints.c:2867
0xb61c4e process_address
        /space/rguenther/tramp3d/trunk/gcc/lra-constraints.c:3124
0xb62607 curr_insn_transform
        /space/rguenther/tramp3d/trunk/gcc/lra-constraints.c:3419
0xb65250 lra_constraints(bool)
        /space/rguenther/tramp3d/trunk/gcc/lra-constraints.c:4421

Richard's initial comments

that looks like a latent issue to me in an area of GCC I am not
familiar with.  I suggest to open a bugreport and CC Vladimir.

The r226850 change caused us to eliminate an induction variable
early (I suspect IVOPTs would have done this later anyway, but
I did not verify that):

Replaced redundant PHI node defining bl_2 with c_1
Replaced c_1 + 1 with bl_15 in all uses of c_16 = c_1 + 1;
Removing dead stmt c_16 = c_1 + 1;
Removing dead stmt bl_2 = PHI <0(2), bl_15(3)>