[llvm] [RISCV] Expand vp.stride.load to splat of a scalar load. (PR #98140)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `llvm` at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/2190

Here is the relevant piece of the build log for the reference:
```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/llvm-x86_64-debian-dylib/build/bin/llc -mtriple=riscv32 -mattr=+m,+d,+zfh,+v,+zvfh      -verify-machineinstrs < /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll      -check-prefixes=CHECK,CHECK-RV32
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll -check-prefixes=CHECK,CHECK-RV32
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llc -mtriple=riscv32 -mattr=+m,+d,+zfh,+v,+zvfh -verify-machineinstrs
RUN: at line 5: /b/1/llvm-x86_64-debian-dylib/build/bin/llc -mtriple=riscv64 -mattr=+m,+d,+zfh,+v,+zvfh      -verify-machineinstrs < /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll      -check-prefixes=CHECK,CHECK-RV64,CHECK-OPT
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llc -mtriple=riscv64 -mattr=+m,+d,+zfh,+v,+zvfh -verify-machineinstrs
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll -check-prefixes=CHECK,CHECK-RV64,CHECK-OPT
/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll:640:19: error: CHECK-OPT-NEXT: is not on the line after the previous match
; CHECK-OPT-NEXT: vsetivli zero, 4, e8, mf4, ta, ma
                  ^
<stdin>:688:2: note: 'next' match was here
 vsetivli zero, 4, e8, mf4, ta, ma
 ^
<stdin>:686:9: note: previous match ended here
# %bb.0:
        ^
<stdin>:687:1: note: non-matching line after previous match is here
 lbu a0, 0(a0)
^
/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll:658:19: error: CHECK-OPT-NEXT: is not on the line after the previous match
; CHECK-OPT-NEXT: vsetivli zero, 4, e16, mf2, ta, ma
                  ^
<stdin>:703:2: note: 'next' match was here
 vsetivli zero, 4, e16, mf2, ta, ma
 ^
<stdin>:701:9: note: previous match ended here
# %bb.0:
        ^
<stdin>:702:1: note: non-matching line after previous match is here
 flh fa5, 0(a0)
^

Input file: <stdin>
Check file: /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-strided-vpload.ll

-dump-input=help explains the following input dump.

Input was:
<<<<<<
          .
          .
          .
        683:  .variant_cc zero_strided_unmasked_vpload_4i8_i8 
        684: zero_strided_unmasked_vpload_4i8_i8: # @zero_strided_unmasked_vpload_4i8_i8 
        685:  .cfi_startproc 
        686: # %bb.0: 
...

```

https://github.com/llvm/llvm-project/pull/98140