[llvm] [RISCV][GISEL] Legalize G_INSERT_SUBVECTOR (PR #108859)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/7470

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 2: /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=riscv64 -mattr=+v -run-pass=legalizer /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir -o - | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir -check-prefixes=CHECK,RV32
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir -check-prefixes=CHECK,RV32
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=riscv64 -mattr=+v -run-pass=legalizer /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir -o -

# After Legalizer
# Machine code for function insert_subvector_nxv8i16_nxv1i16: IsSSA, TracksLiveness, Legalized

bb.0.entry:
  liveins: $v8m8
  %0:_(<vscale x 8 x s16>) = COPY $v8
  %1:_(<vscale x 1 x s16>) = G_IMPLICIT_DEF
  %3:_(<vscale x 4 x s16>) = G_EXTRACT_SUBVECTOR %0:_(<vscale x 8 x s16>), 4
  %4:_(<vscale x 4 x s16>) = G_IMPLICIT_DEF
  %5:_(<vscale x 4 x s16>) = G_INSERT_SUBVECTOR %4:_, %1:_(<vscale x 1 x s16>), 0
  %6:_(s64) = G_CONSTANT i64 -1
  %7:_(<vscale x 8 x s1>) = G_VMSET_VL %6:_(s64)
  %10:_(s64) = G_READ_VLENB
  %11:_(s64) = G_CONSTANT i64 3
  %8:_(s64) = G_LSHR %10:_, %11:_(s64)
  %9:_(<vscale x 4 x s16>) = G_VMV_V_V_VL %3:_, %5:_(<vscale x 4 x s16>), %8:_(s64)
  %2:_(<vscale x 8 x s16>) = G_INSERT_SUBVECTOR %0:_, %9:_(<vscale x 4 x s16>), 4
  $v8 = COPY %2:_(<vscale x 8 x s16>)
  PseudoRET implicit $v8

# End machine code for function insert_subvector_nxv8i16_nxv1i16.

*** Bad machine code: Extra explicit operand on non-variadic instruction ***
- function:    insert_subvector_nxv8i16_nxv1i16
- basic block: %bb.0 entry (0xa76f218)
- instruction: %9:_(<vscale x 4 x s16>) = G_VMV_V_V_VL %3:_, %5:_(<vscale x 4 x s16>), %8:_(s64)
- operand 3:   %8:_
LLVM ERROR: Found 1 machine code errors.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=riscv64 -mattr=+v -run-pass=legalizer /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir -o -
1.	Running pass 'Function Pass Manager' on module '/b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rvv/legalize-insert-subvector.mir'.
2.	Running pass 'Verify generated machine code' on function '@insert_subvector_nxv8i16_nxv1i16'
 #0 0x00000000035d3317 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc+0x35d3317)
 #1 0x00000000035d0dce llvm::sys::RunSignalHandlers() (/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc+0x35d0dce)
 #2 0x00000000035d39cf SignalHandler(int) Signals.cpp:0:0
 #3 0x00007fa797fbe140 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x13140)
 #4 0x00007fa797ad2d51 raise (/lib/x86_64-linux-gnu/libc.so.6+0x38d51)
 #5 0x00007fa797abc537 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22537)
 #6 0x0000000003543f2a llvm::report_fatal_error(llvm::Twine const&, bool) (/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc+0x3543f2a)
 #7 0x00000000028009ba (/b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc+0x28009ba)
...

```

</details>

https://github.com/llvm/llvm-project/pull/108859