[Bug target/68293] New: [6 Regression] ICE: in prepare_cmp_insn, at optabs.c:3813 with vector compare with -O0 @ aarch64

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68293

            Bug ID: 68293
           Summary: [6 Regression] ICE: in prepare_cmp_insn, at
                    optabs.c:3813 with vector compare with -O0 @ aarch64
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---

Created attachment 36684
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36684&action=edit
reduced testcase

This seems to be a recent regression.

r230014 is fine (only 6 ICEs in prepare_cmp_insn in the whole testsuite run),
r230115 and r230151 are failing (hundreds of ICEs)

Compiler output:
$ cc1 -quiet testcase.c
testcase.c: In function 'foo':
testcase.c:6:13: internal compiler error: in prepare_cmp_insn, at optabs.c:3813
   return *u == *v;
             ^

0xa00156 prepare_cmp_insn
        /repo/gcc-trunk/gcc/optabs.c:3813
0xa00251 emit_cmp_and_jump_insns(rtx_def*, rtx_def*, rtx_code, rtx_def*,
machine_mode, int, rtx_def*, int)
        /repo/gcc-trunk/gcc/optabs.c:3960
0x737d82 do_compare_rtx_and_jump(rtx_def*, rtx_def*, rtx_code, int,
machine_mode, rtx_def*, rtx_code_label*, rtx_code_label*, int)
        /repo/gcc-trunk/gcc/dojump.c:1140
0x738d58 do_compare_and_jump
        /repo/gcc-trunk/gcc/dojump.c:1219
0x73b089 do_jump_1(tree_code, tree_node*, tree_node*, rtx_code_label*,
rtx_code_label*, int)
        /repo/gcc-trunk/gcc/dojump.c:231
0x7ee12f expand_expr_real_2(separate_ops*, rtx_def*, machine_mode,
expand_modifier)
        /repo/gcc-trunk/gcc/expr.c:9076
0x6c5d6b expand_gimple_stmt_1
        /repo/gcc-trunk/gcc/cfgexpand.c:3613
0x6c5d6b expand_gimple_stmt
        /repo/gcc-trunk/gcc/cfgexpand.c:3673
0x6c76e2 expand_gimple_basic_block
        /repo/gcc-trunk/gcc/cfgexpand.c:5679
0x6cce6e execute
        /repo/gcc-trunk/gcc/cfgexpand.c:6291
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
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$ xgcc -v              
Using built-in specs.
COLLECT_GCC=/repo/build-trunk-230151-checking-yes-rtl-df-nographite-aarch64/gcc/xgcc
Target: aarch64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-checking=yes,rtl,df --without-cloog --without-ppl --without-isl
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=aarch64-unknown-linux-gnu
--with-ld=/usr/bin/aarch64-unknown-linux-gnu-ld
--with-as=/usr/bin/aarch64-unknown-linux-gnu-as --with-sysroot=/chroot/aarch64
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-230151-checking-yes-rtl-df-nographite-aarch64
Thread model: posix
gcc version 6.0.0 20151111 (experimental) (GCC) 

Tested revisions:
r230151 - ICE
r230115 - ICE
r230014 - OK
4_5-branch r230093 - OK