[Bug rtl-optimization/52170] New: ICE in trunc_int_for_mode, at explow.c:57 during simplify_plus_minus

["Greta.Yorsh at arm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52170

             Bug #: 52170
           Summary: ICE in trunc_int_for_mode, at explow.c:57 during
                    simplify_plus_minus
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Greta.Yorsh@arm.com


Created attachment 26609
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26609
testcase that triggers the ICE

cc1 -quiet -mcpu=cortex-a9 -mfloat-abi=softfp -mfpu=neon -O3 smallest.c
smallest.c: In function 'f0a':
smallest.c:24:1: internal compiler error: in trunc_int_for_mode, at explow.c:57

57: gcc_assert (SCALAR_INT_MODE_P (mode));

(gdb) info stack
#0  fancy_abort (file=0x132ccd0 "/work/local-checkouts/gcc-fsf/gcc/explow.c",
line=57, function=0x132d130 "trunc_int_for_mode") at
/work/local-checkouts/gcc-fsf/gcc/diagnostic.c:899
#1  0x0000000000753919 in trunc_int_for_mode (c=1, mode=V16QImode) at
/work/local-checkouts/gcc-fsf/gcc/explow.c:57
#2  0x000000000073c90f in gen_int_mode (c=1, mode=V16QImode) at
/work/local-checkouts/gcc-fsf/gcc/emit-rtl.c:421
#3  0x0000000000adba40 in neg_const_int (mode=V16QImode, i=0x7ffff765c460) at
/work/local-checkouts/gcc-fsf/gcc/simplify-rtx.c:70
#4  0x0000000000ae96bf in simplify_plus_minus (code=MINUS, mode=V16QImode,
op0=0x7ffff75f17e0, op1=0x7ffff76010e0) at
/work/local-checkouts/gcc-fsf/gcc/simplify-rtx.c:3963
#5  0x0000000000ae2e20 in simplify_binary_operation_1 (code=MINUS,
mode=V16QImode, op0=0x7ffff75f17e0, op1=0x7ffff76010e0, trueop0=0x7ffff75f17e0,
trueop1=0x7ffff76010e0) at
/work/local-checkouts/gcc-fsf/gcc/simplify-rtx.c:2307
#6  0x0000000000ae1049 in simplify_binary_operation (code=MINUS,
mode=V16QImode, op0=0x7ffff75f17e0, op1=0x7ffff76010e0) at
/work/local-checkouts/gcc-fsf/gcc/simplify-rtx.c:1909
#7  0x0000000001116fe8 in combine_simplify_rtx (x=0x7ffff75f1828,
op0_mode=V16QImode, in_dest=0, in_cond=0) at
/work/local-checkouts/gcc-fsf/gcc/combine.c:5459
#8  0x000000000111688a in subst (x=0x7ffff75f1828, from=0x7ffff75ff800,
to=0x7ffff75f17e0, in_dest=0, in_cond=0, unique_copy=0) at
/work/local-checkouts/gcc-fsf/gcc/combine.c:5292
#9  0x0000000001116674 in subst (x=0x7ffff75f1840, from=0x7ffff75ff800,
to=0x7ffff75f17e0, in_dest=0, in_cond=0, unique_copy=0) at
/work/local-checkouts/gcc-fsf/gcc/combine.c:5228
#10 0x0000000001110569 in try_combine (i3=0x7ffff7600678, i2=0x7ffff7600630,
i1=0x7ffff76005e8, i0=0x0, new_direct_jump_p=0x7fffffffe05c,
last_combined_insn=0x7ffff7600678) at
/work/local-checkouts/gcc-fsf/gcc/combine.c:3253
#11 0x000000000110b0d8 in combine_instructions (f=0x7ffff75c4a00, nregs=582) at
/work/local-checkouts/gcc-fsf/gcc/combine.c:1340
#12 0x000000000112be4d in rest_of_handle_combine () at
/work/local-checkouts/gcc-fsf/gcc/combine.c:13953
#13 0x0000000000a238cf in execute_one_pass (pass=0x18e6500) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2081
#14 0x0000000000a23abd in execute_pass_list (pass=0x18e6500) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2136
#15 0x0000000000a23ade in execute_pass_list (pass=0x18dcb40) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2137
#16 0x0000000000bc8d2a in tree_rest_of_compilation (fndecl=0x7ffff759c300) at
/work/local-checkouts/gcc-fsf/gcc/tree-optimize.c:422
#17 0x000000000069e420 in cgraph_expand_function (node=0x7ffff75c1000) at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1829
#18 0x000000000069e5eb in cgraph_expand_all_functions () at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1896
#19 0x000000000069f131 in cgraph_optimize () at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:2210
#20 0x000000000069c16d in cgraph_finalize_compilation_unit () at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1338
#21 0x00000000004cd66d in c_write_global_declarations () at
/work/local-checkouts/gcc-fsf/gcc/c-decl.c:10030
#22 0x0000000000b1634a in compile_file () at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:573
#23 0x0000000000b185a8 in do_compile () at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:1938
#24 0x0000000000b1871f in toplev_main (argc=7, argv=0x7fffffffe448) at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:2014
#25 0x00000000005ce980 in main (argc=7, argv=0x7fffffffe448) at
/work/local-checkouts/gcc-fsf/gcc/main.c:36

Fails on trunk. 

The problem seems to be that the "mode" argument of simplify_plus_minus, which
satisfies INTEGRAL_MODE_P (mode), is passed on to trunc_int_for_mode, which
requires stronger SCALAR_INT_MODE_P (mode). The assert fails in the attached
test case, because the mode is V16QImode a vector mode not scalar mode.