[Bug target/114801] New: [14 Regression] arm: ICE in find_cached_value, at rtx-vector-builder.cc:100 with MVE intrinsics

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114801

            Bug ID: 114801
           Summary: [14 Regression] arm: ICE in find_cached_value, at
                    rtx-vector-builder.cc:100 with MVE intrinsics
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

The following testcase:

#include <arm_mve.h>
uint32x4_t test_9() {
  return vdupq_m_n_u32(vdupq_n_u32(0), 0, 0xcccc);
}

ICEs with -march=armv8.1-m.main+mve -mfloat-abi=hard on the trunk. This appears
to be a regression from GCC 13.

For a preprocessed reproducer, take the following:

$ cat t.c
#pragma GCC arm "arm_mve_types.h"
#pragma GCC arm "arm_mve.h" false
uint32x4_t test_9() {
  return vdupq_m_n_u32(vdupq_n_u32(0), 0, 0xcccc);
}
$ gcc/xgcc -B gcc -c t.c -S -o /dev/null -march=armv8.1-m.main+mve
-mfloat-abi=hard
during RTL pass: expand
t.c: In function ‘test_9’:
t.c:4:10: internal compiler error: in find_cached_value, at
rtx-vector-builder.cc:100
    4 |   return vdupq_m_n_u32(vdupq_n_u32(0), 0, 0xcccc);
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0x2a7fc16 rtx_vector_builder::find_cached_value()
        /home/alecop01/toolchain/src/gcc/gcc/rtx-vector-builder.cc:100
0x2a7f9c9 rtx_vector_builder::build()
        /home/alecop01/toolchain/src/gcc/gcc/rtx-vector-builder.cc:64
0x2adff41 native_decode_vector_rtx(machine_mode, vec<unsigned char, va_heap,
vl_ptr> const&, unsigned int, unsigned int, unsigned int)
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7269
0x2ae0068 native_decode_rtx(machine_mode, vec<unsigned char, va_heap, vl_ptr>
const&, unsigned int)
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7289
0x2ae10c4 simplify_immed_subreg
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7529
0x2ae1807 simplify_context::simplify_subreg(machine_mode, rtx_def*,
machine_mode, poly_int<1u, unsigned long>)
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7603
0x2ae31f2 simplify_context::simplify_gen_subreg(machine_mode, rtx_def*,
machine_mode, poly_int<1u, unsigned long>)
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7875
0x2ae3644 simplify_context::lowpart_subreg(machine_mode, rtx_def*,
machine_mode)
        /home/alecop01/toolchain/src/gcc/gcc/simplify-rtx.cc:7904
0x1e92c3e lowpart_subreg(machine_mode, rtx_def*, machine_mode)
        /home/alecop01/toolchain/src/gcc/gcc/rtl.h:3565
0x22f4d11 gen_lowpart_common(machine_mode, rtx_def*)
        /home/alecop01/toolchain/src/gcc/gcc/emit-rtl.cc:1627
0x2a7f336 gen_lowpart_general(machine_mode, rtx_def*)
        /home/alecop01/toolchain/src/gcc/gcc/rtlhooks.cc:48
0x327a20e arm_mve::function_expander::add_input_operand(insn_code, rtx_def*)
       
/home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-mve-builtins.cc:2103
0x327a887 arm_mve::function_expander::use_cond_insn(insn_code, unsigned int)
       
/home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-mve-builtins.cc:2227
0x3282fe2
arm_mve::unspec_mve_function_exact_insn::expand(arm_mve::function_expander&)
const
       
/home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-mve-builtins-functions.h:339
0x327ab65 arm_mve::function_expander::expand()
       
/home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-mve-builtins.cc:2287
0x327ae1d arm_mve::expand_builtin(unsigned int, tree_node*, rtx_def*)
       
/home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-mve-builtins.cc:2352
0x3275215 arm_expand_builtin(tree_node*, rtx_def*, rtx_def*, machine_mode, int)
        /home/alecop01/toolchain/src/gcc/gcc/config/arm/arm-builtins.cc:4103
0x20fd3b9 expand_builtin(tree_node*, rtx_def*, rtx_def*, machine_mode, int)
        /home/alecop01/toolchain/src/gcc/gcc/builtins.cc:7769
0x236a0ed expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier, rtx_def**, bool)
        /home/alecop01/toolchain/src/gcc/gcc/expr.cc:12350
0x235c6d1 expand_expr_real(tree_node*, rtx_def*, machine_mode, expand_modifier,
rtx_def**, bool)
        /home/alecop01/toolchain/src/gcc/gcc/expr.cc:9440
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.