[Bug tree-optimization/61917] [4.9 Regression] ICE on valid code at -O3 on x86_64-linux-gnu in vectorizable_reduction, at tree-vect-loop.c:4913

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61917

--- Comment #15 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Kai Tietz from comment #14)
> (In reply to H.J. Lu from comment #13)
> > (In reply to Kai Tietz from comment #12)
> > > Hmm, just retested it for gcc's trunk.  Can't reproduce it.  I will retest
> > > with current trunk, I might have a different patch in tree, which makes the
> > > difference here.
> > > Additionally, what target you are using?
> > 
> > Also happened on 4.9 branch:
> 
> So for me it doesn't happen on trunk, so the "Also" seems to me something
> special for you.  I will recheck 4.9, as here we might have a regression I
> didn't caught ...

I don't know why you didn't see it:

Starting program: /export/build/gnu/gcc-4.9/build-x86_64-linux/gcc/cc1
-fpreprocessed /tmp/x.i -quiet -dumpbase x.i -mtune=generic -march=x86-64
-auxbase x -O -version -ftree-vectorize -o x.i
GNU C (GCC) version 4.9.3 20150225 (prerelease) (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.8.3 20140911 (Red Hat 4.8.3-7), GMP version
5.1.2, MPFR version 3.1.2, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C (GCC) version 4.9.3 20150225 (prerelease) (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.8.3 20140911 (Red Hat 4.8.3-7), GMP version
5.1.2, MPFR version 3.1.2, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: e64a271cb64a39ff067a5fd30c57a8d9

Program received signal SIGSEGV, Segmentation fault.
0x0000000000c1efa1 in gimple_code (g=0x0)
    at /export/gnu/import/git/gcc-release/gcc/gimple.h:1406
1406      return g->code;
(gdb) bt
#0  0x0000000000c1efa1 in gimple_code (g=0x0)
    at /export/gnu/import/git/gcc-release/gcc/gimple.h:1406
#1  0x0000000000c2bc5d in vectorizable_reduction (
    stmt=<gimple_assign 0x7ffff19e0000>, gsi=0x0, vec_stmt=0x0, slp_node=0x0)
    at /export/gnu/import/git/gcc-release/gcc/tree-vect-loop.c:4915
#2  0x0000000000c1bcca in vect_analyze_stmt (
    stmt=<gimple_assign 0x7ffff19e0000>, need_to_vectorize=0x7fffffffd6af, 
    node=0x0) at /export/gnu/import/git/gcc-release/gcc/tree-vect-stmts.c:7107
#3  0x0000000000c1b723 in vect_analyze_stmt (
    stmt=<gimple_assign 0x7ffff19d32c0>, need_to_vectorize=0x7fffffffd6af, 
    node=0x0) at /export/gnu/import/git/gcc-release/gcc/tree-vect-stmts.c:7023
#4  0x0000000000c24048 in vect_analyze_loop_operations (loop_vinfo=0x1a75950, 
    slp=false) at /export/gnu/import/git/gcc-release/gcc/tree-vect-loop.c:1505
#5  0x0000000000c247ee in vect_analyze_loop_2 (loop_vinfo=0x1a75950)
    at /export/gnu/import/git/gcc-release/gcc/tree-vect-loop.c:1766
#6  0x0000000000c24b73 in vect_analyze_loop (loop=0x7ffff19d50a0)
    at /export/gnu/import/git/gcc-release/gcc/tree-vect-loop.c:1864
#7  0x0000000000c41516 in vectorize_loops ()
    at /export/gnu/import/git/gcc-release/gcc/tree-vectorizer.c:430
#8  0x0000000000b713d3 in tree_loop_vectorize ()
    at /export/gnu/import/git/gcc-release/gcc/tree-ssa-loop.c:154
#9  0x0000000000b7145d in (anonymous namespace)::pass_vectorize::execute (
    this=0x1a20150)
---Type <return> to continue, or q <return> to quit---
    at /export/gnu/import/git/gcc-release/gcc/tree-ssa-loop.c:189
#10 0x000000000095dde6 in execute_one_pass (
    pass=<opt_pass* 0x1a20150 "vect"(119)>)
    at /export/gnu/import/git/gcc-release/gcc/passes.c:2233
#11 0x000000000095dfff in execute_pass_list (
    pass=<opt_pass* 0x1a20150 "vect"(119)>)
    at /export/gnu/import/git/gcc-release/gcc/passes.c:2286
#12 0x000000000095e030 in execute_pass_list (
    pass=<opt_pass* 0x1a1fa30 "loop"(101)>)
    at /export/gnu/import/git/gcc-release/gcc/passes.c:2287
#13 0x000000000095e030 in execute_pass_list (
    pass=<opt_pass* 0x1a1e950 "*all_optimizations"(-1)>)
    at /export/gnu/import/git/gcc-release/gcc/passes.c:2287
#14 0x00000000006bb569 in expand_function (
    node=<cgraph_node* 0x7ffff18a9e18 "f">)
    at /export/gnu/import/git/gcc-release/gcc/cgraphunit.c:1774
#15 0x00000000006bb9ca in expand_all_functions ()
    at /export/gnu/import/git/gcc-release/gcc/cgraphunit.c:1908
#16 0x00000000006bc2ed in compile ()
    at /export/gnu/import/git/gcc-release/gcc/cgraphunit.c:2252
#17 0x00000000006bc3c8 in finalize_compilation_unit ()
    at /export/gnu/import/git/gcc-release/gcc/cgraphunit.c:2329
#18 0x00000000005817c7 in c_write_global_declarations ()
---Type <return> to continue, or q <return> to quit---q
 at /export/gnu/import/gQuit
(gdb) f 2
#2  0x0000000000c1bcca in vect_analyze_stmt (
    stmt=<gimple_assign 0x7ffff19e0000>, need_to_vectorize=0x7fffffffd6af, 
    node=0x0) at /export/gnu/import/git/gcc-release/gcc/tree-vect-stmts.c:7107
7107                || vectorizable_reduction (stmt, NULL, NULL, NULL)
(gdb) call debug_gimple_stmt (stmt)
patt_25 = a_lsm.8_11 < 0 ? 7 : 0;
(gdb) f 1
#1  0x0000000000c2bc5d in vectorizable_reduction (
    stmt=<gimple_assign 0x7ffff19e0000>, gsi=0x0, vec_stmt=0x0, slp_node=0x0)
    at /export/gnu/import/git/gcc-release/gcc/tree-vect-loop.c:4915
4915      if (gimple_code (reduc_def_stmt) != GIMPLE_PHI)
(gdb) p reduc_def_stmt
$2 = <gimple 0x0>
(gdb)