[Bug tree-optimization/71643] New: [7 Regression] internal compiler error: in redirect_eh_edge_1, at tree-eh.c:2318 after r237427

[jgreenhalgh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71643

            Bug ID: 71643
           Summary: [7 Regression] internal compiler error: in
                    redirect_eh_edge_1, at tree-eh.c:2318 after r237427
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jgreenhalgh at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org, jakub at redhat dot com
  Target Milestone: ---

Created attachment 38755
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38755&action=edit
Reduced testcase

After r237427:

        PR tree-optimization/71520
        * tree-ssa-tail-merge.c (find_duplicate): Handle labels.
        (replace_block_by): Move user labels from bb1 to bb2.

        * gcc.dg/tree-ssa/pr71520.c: New test.

I'm seeing the following ICE for the attached reduced testcase when compiling
with -O3 on aarch64-none-linux-gnu/x86_64-unknown-linux-gnu:

x.cpp:30:1: internal compiler error: in redirect_eh_edge_1, at tree-eh.c:2318
 foo (void)
 ^~~
0xd2d737 redirect_eh_edge_1
        .../gcc/tree-eh.c:2318
0xd2d8e7 redirect_eh_edge(edge_def*, basic_block_def*)
        .../gcc/tree-eh.c:2370
0xd12d5e gimple_redirect_edge_and_branch
        .../gcc/tree-cfg.c:5664
0x8d2976 redirect_edge_and_branch(edge_def*, basic_block_def*)
        .../gcc/cfghooks.c:356
0xec9098 replace_block_by
        .../gcc/tree-ssa-tail-merge.c:1538
0xec9098 apply_clusters
        .../gcc/tree-ssa-tail-merge.c:1635
0xec9098 tail_merge_optimize(unsigned int)
        .../gcc/tree-ssa-tail-merge.c:1743
0xe78871 execute
        .../gcc/tree-ssa-pre.c:4826
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