[llvm-bugs] [Bug 41635] New: [aarch64] llvm.experimental.reduce.{and, any} don't lower properly for boolean vectors

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41635

            Bug ID: 41635
           Summary: [aarch64] llvm.experimental.reduce.{and, any} don't
                    lower properly for boolean vectors
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: AArch64
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: arnaud.degrandmaison at arm.com, gonzalobg88 at gmail.com,
                    llvm-bugs at lists.llvm.org, peter.smith at linaro.org,
                    Ties.Stuij at arm.com

Split off from [Bug #36702], AARCH64 generates poor code for boolean reduction
from generic IR - either with the llvm.experimental.vector.reduce intrinsics
(which expand to a shuffle reduction chain) or with bitcasts of the comparison
result mask:

https://godbolt.org/z/wchsJ6

e.g.

## AArch64

LLVM6:

all_8x8:
 ldr     d0, [x0]
 umov    w8, v0.b[0]
 umov    w9, v0.b[1]
 tst     w8, #0xff
 umov    w10, v0.b[2]
 cset    w8, ne
 tst     w9, #0xff
 cset    w9, ne
 tst     w10, #0xff
 umov    w10, v0.b[3]
 and     w8, w8, w9
 cset    w9, ne
 tst     w10, #0xff
 umov    w10, v0.b[4]
 and     w8, w9, w8
 cset    w9, ne
 tst     w10, #0xff
 umov    w10, v0.b[5]
 and     w8, w9, w8
 cset    w9, ne
 tst     w10, #0xff
 umov    w10, v0.b[6]
 and     w8, w9, w8
 cset    w9, ne
 tst     w10, #0xff
 umov    w10, v0.b[7]
 and     w8, w9, w8
 cset    w9, ne
 tst     w10, #0xff
 and     w8, w9, w8
 cset    w9, ne
 and     w0, w9, w8
 ret
any_8x8:
 ldr     d0, [x0]
 umov    w8, v0.b[0]
 umov    w9, v0.b[1]
 orr     w8, w8, w9
 umov    w9, v0.b[2]
 orr     w8, w8, w9
 umov    w9, v0.b[3]
 orr     w8, w8, w9
 umov    w9, v0.b[4]
 orr     w8, w8, w9
 umov    w9, v0.b[5]
 orr     w8, w8, w9
 umov    w9, v0.b[6]
 orr     w8, w8, w9
 umov    w9, v0.b[7]
 orr     w8, w8, w9
 tst     w8, #0xff
 cset    w0, ne
 ret

Manually generated:

all_8x8:
 ldr     d0, [x0]
 mov     v0.d[1], v0.d[0]
 uminv   b0, v0.16b
 fmov    w8, s0
 tst     w8, #0xff
 cset    w0, ne
 ret
any_8x8:
 ldr     d0, [x0]
 mov     v0.d[1], v0.d[0]
 umaxv   b0, v0.16b
 fmov    w8, s0
 tst     w8, #0xff
 cset    w0, ne
 ret

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