[llvm-bugs] [Bug 43056] New: Assertion failure in AArch64 backend: "Detected cycle in SelectionDAG"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=43056

            Bug ID: 43056
           Summary: Assertion failure in AArch64 backend: "Detected cycle
                    in SelectionDAG"
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: AArch64
          Assignee: unassignedbugs at nondot.org
          Reporter: tstellar at redhat.com
                CC: arnaud.degrandmaison at arm.com,
                    llvm-bugs at lists.llvm.org, peter.smith at linaro.org,
                    Ties.Stuij at arm.com
            Blocks: 42474

Created attachment 22397
  --> https://bugs.llvm.org/attachment.cgi?id=22397&action=edit
Original Test Case

Reproduce with:

llc -march=aarch64 -mcpu=thunderxt88 < aarch64-sdag-cycle-reduced.ll

Full error message:

Detected cycle in SelectionDAG
Offending node:
t659: v4f32,i64,ch = AArch64ISD::LD1DUPpost<(load 4 from %ir.96)> t489, t460,
t120
  t460: i64,ch = load<(load 8 from %ir."&context.constants_ptr[]7")> t456, t2,
undef:i64
    t2: i64,ch = CopyFromReg t0, Register:i64 %7
      t1: i64 = Register %7
    t11: i64 = undef
  t120: i64 = shl t118, Constant:i64<2>
    t118: i64 = sign_extend t117
      t117: i32 = extract_vector_elt t589, Constant:i64<0>
        t589: v4i32 = and t584, t587
          t584: v4i32 = AArch64ISD::VSHL t407, Constant:i32<2>
            t407: v4i32 = add t582, t655
              t582: v4i32 = AArch64ISD::VSHL t96, Constant:i32<1>
                t96: v4i32 = bitcast t659
                  t659: v4f32,i64,ch = AArch64ISD::LD1DUPpost<(load 4 from
%ir.96)> t489, t460, t120


                t124: i32 = Constant<1>
              t655: v4i32 = AArch64ISD::MOVIshift Constant:i32<3>,
Constant:i32<0>
                t106: i32 = Constant<3>
                t19: i32 = Constant<0>
            t97: i32 = Constant<2>
          t587: v4i32 = xor t583, t586
            t583: v4i32 = AArch64ISD::CMHS t407, t647
              t407: v4i32 = add t582, t655
                t582: v4i32 = AArch64ISD::VSHL t96, Constant:i32<1>
                  t96: v4i32 = bitcast t659

                  t124: i32 = Constant<1>
                t655: v4i32 = AArch64ISD::MOVIshift Constant:i32<3>,
Constant:i32<0>
                  t106: i32 = Constant<3>
                  t19: i32 = Constant<0>
              t647: v4i32 = AArch64ISD::DUP t457
                t457: i32,ch = load<(load 4 from %ir.95)> t456, t73, undef:i64
                  t73: i64 = add t2, Constant:i64<128>


                  t11: i64 = undef
            t586: v4i32 = BUILD_VECTOR Constant:i32<-1>, Constant:i32<-1>,
Constant:i32<-1>, Constant:i32<-1>
              t585: i32 = Constant<-1>
              t585: i32 = Constant<-1>
              t585: i32 = Constant<-1>
              t585: i32 = Constant<-1>
        t10: i64 = Constant<0>
    t119: i64 = Constant<2>


Referenced Bugs:

https://bugs.llvm.org/show_bug.cgi?id=42474
[Bug 42474] [meta] 9.0.0 Release Blockers
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