[llvm] [GlobalISel] Import llvm.stepvector (PR #115721)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` 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/56/builds/11965

<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 :: Transforms/InstCombine/fcmp-fadd-select.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/clang-x86_64-debian-fast/llvm.obj/bin/opt < /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll -passes=instcombine -S | /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/opt -passes=instcombine -S
+ /b/1/clang-x86_64-debian-fast/llvm.obj/bin/FileCheck /b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll:62:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz <2 x float> [[SEL_NEW]], <float 1.000000e+00, float 1.000000e+00>
              ^
<stdin>:29:99: note: scanning from here
 %sel = call nnan nsz <2 x float> @llvm.maxnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:29:99: note: with "SEL_NEW" equal to "%sel"
 %sel = call nnan nsz <2 x float> @llvm.maxnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:30:2: note: possible intended match here
 %add = fadd nnan nsz <2 x float> %sel, splat (float 1.000000e+00)
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll:130:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz <2 x float> [[SEL_NEW]], <float 1.000000e+00, float 1.000000e+00>
              ^
<stdin>:59:99: note: scanning from here
 %sel = call nnan nsz <2 x float> @llvm.minnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:59:99: note: with "SEL_NEW" equal to "%sel"
 %sel = call nnan nsz <2 x float> @llvm.minnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:60:2: note: possible intended match here
 %add = fadd nnan nsz <2 x float> %sel, splat (float 1.000000e+00)
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll:198:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz <2 x float> [[SEL_NEW]], <float 1.000000e+00, float 1.000000e+00>
              ^
<stdin>:89:99: note: scanning from here
 %sel = call nnan nsz <2 x float> @llvm.maxnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:89:99: note: with "SEL_NEW" equal to "%sel"
 %sel = call nnan nsz <2 x float> @llvm.maxnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
<stdin>:90:2: note: possible intended match here
 %add = fadd nnan nsz <2 x float> %sel, splat (float 1.000000e+00)
 ^
/b/1/clang-x86_64-debian-fast/llvm.src/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll:266:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz <2 x float> [[SEL_NEW]], <float 1.000000e+00, float 1.000000e+00>
              ^
<stdin>:119:99: note: scanning from here
 %sel = call nnan nsz <2 x float> @llvm.minnum.v2f32(<2 x float> %in, <2 x float> zeroinitializer)
                                                                                                  ^
...

```

</details>

https://github.com/llvm/llvm-project/pull/115721