LLVM ERROR: Cannot select: 0xffff6c0e10d8: i32 = vecreduce_mul 0xffff6c072990

[parched]

Running x.py test --stage 1 on aarch64-unknown-linux-gnu I get one failed test as shown below. This is the first time I've run the tests on this target some I'm unsure if it's a regression.
Nightly commit af50e38

CC @gnzlbg ?

---- [ui] ui/run-pass/simd/simd-intrinsic-generic-reduction.rs stdout ----                                                
                                                                                                                          
error: test compilation failed although it shouldn't!                                                                     
status: exit code: 1                                                                                                      
command: "/usr/src/myapp/build/aarch64-unknown-linux-gnu/stage1/bin/rustc" "/usr/src/myapp/src/test/ui/run-pass/simd/simd-
intrinsic-generic-reduction.rs" "--target=aarch64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-d
ynamic" "-o" "/usr/src/myapp/build/aarch64-unknown-linux-gnu/test/ui/run-pass/simd/simd-intrinsic-generic-reduction/a" "-C
rpath" "-O" "-Zunstable-options" "-Lnative=/usr/src/myapp/build/aarch64-unknown-linux-gnu/native/rust-test-helpers" "-L" "
/usr/src/myapp/build/aarch64-unknown-linux-gnu/test/ui/run-pass/simd/simd-intrinsic-generic-reduction/auxiliary" "-A" "unu
sed"                                                                                                                      
stdout:                                                                                                                   
------------------------------------------                                                                                
                                                                                                                          
------------------------------------------                                                                                
stderr:                                                                                                                   
------------------------------------------                                                                                
LLVM ERROR: Cannot select: 0xffff6c0e10d8: i32 = vecreduce_mul 0xffff6c072990                                             
  0xffff6c072990: v4i32,ch = load<(load 16 from constant-pool)> 0xffff6c0c6eb8, 0xffff6c0e1620, undef:i64                 
    0xffff6c0e1620: i64 = AArch64ISD::ADDlow 0xffff6c0727f0, TargetConstantPool:i64<<4 x i32> <i32 1, i32 -2, i32 3, i32 4
>> 0 [TF=34]                                                                                                              
      0xffff6c0727f0: i64 = AArch64ISD::ADRP TargetConstantPool:i64<<4 x i32> <i32 1, i32 -2, i32 3, i32 4>> 0 [TF=1]     
        0xffff6c0728c0: i64 = TargetConstantPool<<4 x i32> <i32 1, i32 -2, i32 3, i32 4>> 0 [TF=1]                        
      0xffff6c0726b8: i64 = TargetConstantPool<<4 x i32> <i32 1, i32 -2, i32 3, i32 4>> 0 [TF=34]                         
    0xffff6c0e1008: i64 = undef                                                                                           
In function: _ZN32simd_intrinsic_generic_reduction4main17h19818a8328796d6fE                                               
                                                                                                                          
------------------------------------------                                                                                
                                                                                                                          
thread '[ui] ui/run-pass/simd/simd-intrinsic-generic-reduction.rs' panicked at 'explicit panic', tools/compiletest/src/run
test.rs:3238:9

[gnzlbg]

I think that's some flavor of https://bugs.llvm.org/show_bug.cgi?id=36796.

On stdsimd/packed_simd we work around this by falling back to scalar code instead, so this shouldn't be used anywhere in the ecosystem on aarch64 anyways.

The "fix" for this is to just ignore this test on aarch64.

[sanxiyn]

Update: LLVM PR36796 is fixed.

[mati865]

It's not merged to Rust's LLVM fork.

[Centril]

@sanxiyn @mati865 How about now?