[llvm] [X86] getFauxShuffleMask - OR(SHUF(),SHUF()) - treat undemanded elements as undef (PR #182678)

[via llvm-commits]

github-actions[bot] wrote:

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

* 169942 tests passed
* 3067 tests skipped
* 1 test failed

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

### LLVM
<details>
<summary>LLVM.Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/opt -S -p=instcombine < /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.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/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# executed command: /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/opt -S -p=instcombine
# 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/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# .---command stderr------------
# | /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll:376:15: error: CHECK-NEXT: expected string not found in input
# | ; CHECK-NEXT: [[MUL_FABS_X:%.*]] = fmul float [[FABS_X]], 0x4170000000000000
# |               ^
# | <stdin>:179:52: note: scanning from here
# |  %fabs.x = call nnan float @llvm.fabs.f32(float %x)
# |                                                    ^
# | <stdin>:179:52: note: with "FABS_X" equal to "%fabs.x"
# |  %fabs.x = call nnan float @llvm.fabs.f32(float %x)
# |                                                    ^
# | <stdin>:180:21: note: possible intended match here
# |  %mul.fabs.x = fmul nnan float %fabs.x, 0x4170000000000000
# |                     ^
# | 
# | Input file: <stdin>
# | Check file: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/Transforms/InstCombine/select-fcmp-fmul-zero-absorbing-value.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |             .
# |             .
# |             .
# |           174:  %select = select i1 %x.is.zero, float %mul.fabs.x, float %fabs.x 
# |           175:  ret float %select 
# |           176: } 
# |           177:  
# |           178: define float @cmp_one_nnan_fabs(float %x) { 
# |           179:  %fabs.x = call nnan float @llvm.fabs.f32(float %x) 
# | next:376'0                                                        X error: no match found
# | next:376'1                                                          with "FABS_X" equal to "%fabs.x"
# |           180:  %mul.fabs.x = fmul nnan float %fabs.x, 0x4170000000000000 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | next:376'2                         ?                                       possible intended match
# |           181:  %x.is.not.zero = fcmp one float %x, 0.000000e+00 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           182:  %select = select i1 %x.is.not.zero, float %fabs.x, float %mul.fabs.x 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           183:  ret float %select 
# | next:376'0     ~~~~~~~~~~~~~~~~~~~
# |           184: } 
# | next:376'0     ~~
# |           185:  
# | next:376'0     ~
# |             .
# |             .
# |             .
# | >>>>>>
# `-----------------------------
# 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/182678