[Bug target/112852] New: [14 Regression] RISCV ICE: vsetvl pass: in partial_subreg_p, at rtl.h:3187 on rv64gcv_zvl512b

["patrick at rivosinc dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112852

            Bug ID: 112852
           Summary: [14 Regression] RISCV ICE: vsetvl pass: in
                    partial_subreg_p, at rtl.h:3187 on rv64gcv_zvl512b
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: patrick at rivosinc dot com
  Target Milestone: ---

Created attachment 56801
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56801&action=edit
-freport-bug output

Only seen on rv64gcv_zvl512b:
pr112598

FAIL: gcc.c-torture/compile/20090907-1.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  (internal compiler
error: in partial_subreg_p, at rtl.h:3187)

Command:
> /scratch/tc-testing/tc-dec-4-trunk/build-rv64gcv/bin/riscv64-unknown-linux-gnu-gcc -march=rv64gcv_zvl512b -mabi=lp64d -O3 20090907-1.c -ftracer -funroll-loops -freport-bug
during RTL pass: vsetvl
20090907-1.c: In function 'metronomefb_probe':
20090907-1.c:84:1: internal compiler error: in partial_subreg_p, at rtl.h:3187
   84 | }
      | ^
0xb3a42b partial_subreg_p(machine_mode, machine_mode)
        ../../../gcc/gcc/rtl.h:3187
0xb3a42b partial_subreg_p(machine_mode, machine_mode)
        ../../../gcc/gcc/rtl.h:3181
0xb3a42b
rtl_ssa::function_info::record_use(rtl_ssa::function_info::build_info&,
rtl_ssa::insn_info*, rtx_obj_reference)
        ../../../gcc/gcc/rtl-ssa/insns.cc:524
0x23ee521
rtl_ssa::function_info::add_insn_to_block(rtl_ssa::function_info::build_info&,
rtx_insn*)
        ../../../gcc/gcc/rtl-ssa/insns.cc:662
0x2a0876d
rtl_ssa::function_info::add_block_contents(rtl_ssa::function_info::build_info&)
        ../../../gcc/gcc/rtl-ssa/blocks.cc:948
0x2a08e8a
rtl_ssa::function_info::start_block(rtl_ssa::function_info::build_info&,
rtl_ssa::bb_info*)
        ../../../gcc/gcc/rtl-ssa/blocks.cc:1064
0x2a08f1c
rtl_ssa::function_info::bb_walker::before_dom_children(basic_block_def*)
        ../../../gcc/gcc/rtl-ssa/blocks.cc:117
0x225c207 dom_walker::walk(basic_block_def*)
        ../../../gcc/gcc/domwalk.cc:311
0x2a0a5c9 rtl_ssa::function_info::process_all_blocks()
        ../../../gcc/gcc/rtl-ssa/blocks.cc:1281
0x23ebb68 rtl_ssa::function_info::function_info(function*)
        ../../../gcc/gcc/rtl-ssa/functions.cc:50
0x1734d12 pre_vsetvl::pre_vsetvl()
        ../../../gcc/gcc/config/riscv/riscv-vsetvl.cc:2218
0x1733527 pass_vsetvl::lazy_vsetvl()
        ../../../gcc/gcc/config/riscv/riscv-vsetvl.cc:3454
0x173391f pass_vsetvl::execute(function*)
        ../../../gcc/gcc/config/riscv/riscv-vsetvl.cc:3518
0x173391f pass_vsetvl::execute(function*)
        ../../../gcc/gcc/config/riscv/riscv-vsetvl.cc:3501
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Preprocessed source stored into /scratch/tmp/ccO9eL35.out file, please attach
this to your bugreport.

Testcase:
https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/gcc.c-torture/compile/20090907-1.c;h=12cf1185b93b973ce21e24039c00d9b7be855894;hb=HEAD

Godbolt:
https://godbolt.org/z/chdK4TnKx

creduced testcase:
char a;
char *b;
int c;
void d() {
  int e = 0, f = 0;
  for (; f <= a; f++)
    if (b[f])
      e = f - 1;
  c = e;
}