[llvm] [SimpleLoopUnswitch] Fix bug in partially invariant unswitching (PR #222118)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 152795 tests passed
* 3273 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### LLVM
<details>
<summary>LLVM.Transforms/SimpleLoopUnswitch/pr219510.ll</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/opt -passes='loop-mssa(simple-loop-unswitch<nontrivial>)' -S < /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/SimpleLoopUnswitch/pr219510.ll | /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/SimpleLoopUnswitch/pr219510.ll
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/opt '-passes=loop-mssa(simple-loop-unswitch<nontrivial>)' -S
# note: command had no output on stdout or stderr
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/FileCheck /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/SimpleLoopUnswitch/pr219510.ll
# .---command stderr------------
# | /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/SimpleLoopUnswitch/pr219510.ll:7:15: error: CHECK-NEXT: is not on the line after the previous match
# | ; CHECK-NEXT: %lv = load i32, ptr %ptr
# |               ^
# | <stdin>:40:2: note: 'next' match was here
# |  %lv = load i32, ptr %ptr, align 4
# |  ^
# | <stdin>:20:22: note: previous match ended here
# |  call void @barrier()
# |                      ^
# | <stdin>:21:1: note: non-matching line after previous match is here
# |  br label %noclobber.us
# | ^
# | 
# | Input file: <stdin>
# | Check file: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/SimpleLoopUnswitch/pr219510.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |           .
# |           .
# |           .
# |          15: entry.split.us: ; preds = %entry 
# |          16:  br label %loop.header.us 
# |          17:  
# |          18: loop.header.us: ; preds = %loop.latch.us, %entry.split.us 
# |          19:  %iv.us = phi i32 [ 0, %entry.split.us ], [ %iv.next.us, %loop.latch.us ] 
# |          20:  call void @barrier() 
# | next:7'0                         {   search range start (exclusive)
# |          21:  br label %noclobber.us 
# |          22:  
# |          23: noclobber.us: ; preds = %loop.header.us 
# |          24:  br label %loop.latch.us 
# |          25:  
# |           .
# |           .
# |           .
# |          35:  br label %loop.header 
# |          36:  
# |          37: loop.header: ; preds = %loop.latch, %entry.split 
# |          38:  %iv = phi i32 [ 0, %entry.split ], [ %iv.next, %loop.latch ] 
# |          39:  call void @barrier() 
# |          40:  %lv = load i32, ptr %ptr, align 4 
# | next:7'1      !~~~~~~~~~~~~~~~~~~~~~~~            error: match on wrong line
# |          41:  %sc = icmp eq i32 %lv, 100 
# |          42:  br i1 %sc, label %noclobber, label %clobber 
# |          43:  
# |          44: noclobber: ; preds = %loop.header 
# |          45:  br label %loop.latch 
# |           .
# |           .
# |           .
# |          61: } 
# |          62:  
# |          63: attributes #0 = { memory(read) } 
# |          64:  
# |          65: !0 = distinct !{!0, !1} 
# |          66: !1 = !{!"llvm.loop.unswitch.partial.disable"} 
# | next:7'2                                                   } search range end (exclusive)
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/222118