[llvm] [InstCombine] Avoid rewriting multi-use post-inc latch icmps (PR #215989)

[via llvm-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 139678 tests passed
* 3677 tests skipped
* 1 test failed

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

### LLVM
<details>
<summary>LLVM.CodeGen/Thumb2/2009-12-01-LoopIVUsers.ll</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\opt.exe < C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Thumb2\2009-12-01-LoopIVUsers.ll -O3 |    c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=thumbv7-apple-darwin10 -mattr=+neon | c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Thumb2\2009-12-01-LoopIVUsers.ll
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\opt.exe' -O3
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\llc.exe' -mtriple=thumbv7-apple-darwin10 -mattr=+neon
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Thumb2\2009-12-01-LoopIVUsers.ll'
# .---command stderr------------
# | C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Thumb2\2009-12-01-LoopIVUsers.ll:11:14: error: CHECK-NOT: excluded string found in input
# | ; CHECK-NOT: adds
# |              ^
# | <stdin>:86:2: note: found here
# |  adds r1, #1
# |  ^~~~
# | 
# | Input file: <stdin>
# | Check file: C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\Thumb2\2009-12-01-LoopIVUsers.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |           .
# |           .
# |           .
# |          44:  and.w r2, r2, r4, lsl #1 
# |          45:  vadd.i32 q8, q9, q8 
# |          46:  vmov.i32 q10, #0x4 
# |          47:  subs r1, r2, r4 
# |          48:  adds r3, r0, r2 
# |          49:  vldr d18, LCPI0_1 
# | not:11'0         {                search range start (exclusive)
# |          50: LBB0_6: @ %vector.body 
# |          51:  @ =>This Inner Loop Header: Depth=1 
# |          52:  vmul.i32 q0, q8, q8 
# |          53:  subs r2, #4 
# |          54:  vadd.i32 q8, q8, q10 
# |           .
# |           .
# |           .
# |          81: LBB0_8: @ %bb4.preheader15 
# |          82:  vldr d16, LCPI0_1 
# |          83: LBB0_9: @ %bb4 
# |          84:  @ =>This Inner Loop Header: Depth=1 
# |          85:  mul r2, r1, r1 
# |          86:  adds r1, #1 
# | not:11'1      !~~~          error: no match expected
# |          87:  cmp r1, r4 
# |          88:  vmov s0, r2 
# |          89:  vcvt.f64.s32 d17, s0 
# |          90:  vmul.f64 d17, d17, d16 
# |          91:  vcvt.s32.f64 s0, d17 
# |           .
# |           .
# |           .
# |         105: LCPI0_1: 
# |         106:  .long 3367254360 @ double 1.234 
# |         107:  .long 1072938614 
# |         108:  .end_data_region 
# |         109:  @ -- End function 
# |         110: .subsections_via_symbols 
# | not:11'2      }                         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/215989