[llvm] [AMDGPU] Fix @llvm.amdgcn.cs.chain with callee not provably uniform (PR #114200)

[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/11424

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

```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /b/1/llvm-x86_64-debian-dylib/build/bin/llc -global-isel=1 -mtriple=amdgcn--amdpal -mcpu=gfx1100 -mattr=+wavefrontsize32 -stop-after=finalize-isel -verify-machineinstrs < /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck -check-prefix=GISEL-GFX11 /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck -check-prefix=GISEL-GFX11 /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llc -global-isel=1 -mtriple=amdgcn--amdpal -mcpu=gfx1100 -mattr=+wavefrontsize32 -stop-after=finalize-isel -verify-machineinstrs
/b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll:674:22: error: GISEL-GFX11-NEXT: expected string not found in input
 ; GISEL-GFX11-NEXT: $sgpr0 = COPY [[COPY3]]
                     ^
<stdin>:893:27: note: scanning from here
 %2:vgpr_32 = COPY $vgpr10
                          ^
<stdin>:893:27: note: with "COPY3" equal to "%1"
 %2:vgpr_32 = COPY $vgpr10
                          ^
<stdin>:896:2: note: possible intended match here
 $sgpr0 = COPY %7
 ^

Input file: <stdin>
Check file: /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/CodeGen/AMDGPU/isel-amdgcn-cs-chain-intrinsic-w32.ll

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

Input was:
<<<<<<
            .
            .
            .
          888:  %3:vgpr_32 = COPY $vgpr8 
          889:  %4:vgpr_32 = COPY $vgpr9 
          890:  %8:vreg_64 = REG_SEQUENCE %3, %subreg.sub0, %4, %subreg.sub1 
          891:  %0:ccr_sgpr_64 = COPY %8 
          892:  %1:sreg_32 = COPY $sgpr0 
          893:  %2:vgpr_32 = COPY $vgpr10 
next:674'0                               X error: no match found
next:674'1                                 with "COPY3" equal to "%1"
          894:  %9:vgpr_32 = COPY %1 
next:674'0     ~~~~~~~~~~~~~~~~~~~~~~
          895:  %7:sreg_32 = V_READFIRSTLANE_B32 %9, implicit $exec 
next:674'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          896:  $sgpr0 = COPY %7 
next:674'0     ~~~~~~~~~~~~~~~~~~
next:674'2      ?                 possible intended match
          897:  $vgpr8 = COPY %2 
next:674'0     ~~~~~~~~~~~~~~~~~~
          898:  SI_CS_CHAIN_TC_W32 %0, 0, 0, -1, amdgpu_allvgprs, implicit $sgpr0, implicit $vgpr8 
next:674'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/114200