[Bug target/115862] New: [15] RISC-V: ICE during RTL combine pass in malloc.c for zvl512b and zvl1024b

[ewlu at rivosinc dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115862

            Bug ID: 115862
           Summary: [15] RISC-V: ICE during RTL combine pass in malloc.c
                    for zvl512b and zvl1024b
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ewlu at rivosinc dot com
  Target Milestone: ---

Created attachment 58627
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58627&action=edit
-freport-bug output zvl512b

We're seeing an ICE when building glibc for rv64gcv with zvl512b and zvl1024b
on our postcommit

https://github.com/patrick-rivos/gcc-postcommit-ci/issues/1318

Haven't bisected down to which commit but it's still present on trunk as of
r15-1952-g0c27eade475

during RTL pass: combine
malloc.c: In function '__libc_mallinfo':
malloc.c:5367:1: internal compiler error: in smallest_mode_for_size, at
stor-layout.cc:356
 5367 | }
      | ^
0x2da7802 internal_error(char const*, ...)
        ../../../gcc/gcc/diagnostic-global-context.cc:491
0xc708d8 fancy_abort(char const*, int, char const*)
        ../../../gcc/gcc/diagnostic.cc:1725
0x139f897 smallest_mode_for_size(poly_int<2u, unsigned long>, mode_class)
        ../../../gcc/gcc/stor-layout.cc:356
0x124f2ea smallest_int_mode_for_size(poly_int<2u, unsigned long>)
        ../../../gcc/gcc/machmode.h:916
0x124f2ea get_best_extraction_insn
        ../../../gcc/gcc/optabs-query.cc:208
0x267a8e4 make_extraction
        ../../../gcc/gcc/combine.cc:7779
0x267bbcf make_compound_operation_int
        ../../../gcc/gcc/combine.cc:8186
0x267cc0f make_compound_operation(rtx_def*, rtx_code)
        ../../../gcc/gcc/combine.cc:8471
0x268095e simplify_set
        ../../../gcc/gcc/combine.cc:6975
0x268095e combine_simplify_rtx
        ../../../gcc/gcc/combine.cc:6374
0x2682bff subst
        ../../../gcc/gcc/combine.cc:5630
0x2686c91 try_combine
        ../../../gcc/gcc/combine.cc:3312
0x268bee1 combine_instructions
        ../../../gcc/gcc/combine.cc:1264
0x268bee1 rest_of_handle_combine
        ../../../gcc/gcc/combine.cc:15127
0x268bee1 execute
        ../../../gcc/gcc/combine.cc:15171
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