Commit feb79af8 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r277755: 

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r277755 | tnorthover | 2016-08-04 12:32:28 -0700 (Thu, 04 Aug 2016) | 5 lines

AArch64: don't assume all i128s are BUILD_PAIRs

It leads to a crash when they're not. I'm *sure* I've made this mistake before,
at least once.

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llvm-svn: 288845
parent 1a8a2edb

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

+13 −6
Original line number Diff line number Diff line
@@ -10083,17 +10083,24 @@ static void ReplaceReductionResults(SDNode *N, 
  Results.push_back(SplitVal);

}



static std::pair<SDValue, SDValue> splitInt128(SDValue N, SelectionDAG &DAG) {

  SDLoc DL(N);

  SDValue Lo = DAG.getNode(ISD::TRUNCATE, DL, MVT::i64, N);

  SDValue Hi = DAG.getNode(ISD::TRUNCATE, DL, MVT::i64,

                           DAG.getNode(ISD::SRL, DL, MVT::i128, N,

                                       DAG.getConstant(64, DL, MVT::i64)));

  return std::make_pair(Lo, Hi);

}



static void ReplaceCMP_SWAP_128Results(SDNode *N,

                                       SmallVectorImpl<SDValue> & Results,

                                       SelectionDAG &DAG) {

  assert(N->getValueType(0) == MVT::i128 &&

         "AtomicCmpSwap on types less than 128 should be legal");

  SDValue Ops[] = {N->getOperand(1),

                   N->getOperand(2)->getOperand(0),

                   N->getOperand(2)->getOperand(1),

                   N->getOperand(3)->getOperand(0),

                   N->getOperand(3)->getOperand(1),

                   N->getOperand(0)};

  auto Desired = splitInt128(N->getOperand(2), DAG);

  auto New = splitInt128(N->getOperand(3), DAG);

  SDValue Ops[] = {N->getOperand(1), Desired.first, Desired.second,

                   New.first,        New.second,    N->getOperand(0)};

  SDNode *CmpSwap = DAG.getMachineNode(

      AArch64::CMP_SWAP_128, SDLoc(N),

      DAG.getVTList(MVT::i64, MVT::i64, MVT::i32, MVT::Other), Ops);

llvm/test/CodeGen/AArch64/cmpxchg-O0.ll

+26 −0
Original line number Diff line number Diff line
@@ -73,3 +73,29 @@ define { i128, i1 } @test_cmpxchg_128(i128* %addr, i128 %desired, i128 %new) nou 
  %res = cmpxchg i128* %addr, i128 %desired, i128 %new seq_cst monotonic

  ret { i128, i1 } %res

}



; Original implementation assumed the desired & new arguments had already been

; type-legalized into some kind of BUILD_PAIR operation and crashed when this

; was false.

@var128 = global i128 0

define {i128, i1} @test_cmpxchg_128_unsplit(i128* %addr) {

; CHECK-LABEL: test_cmpxchg_128_unsplit:

; CHECK:     add x[[VAR128:[0-9]+]], {{x[0-9]+}}, :lo12:var128

; CHECK:     ldr [[DESIRED_HI:x[0-9]+]], [x[[VAR128]], #8]

; CHECK:     ldr [[DESIRED_LO:x[0-9]+]], [x[[VAR128]]]

; CHECK:     ldr [[NEW_HI:x[0-9]+]], [x[[VAR128]], #8]

; CHECK:     ldr [[NEW_LO:x[0-9]+]], [x[[VAR128]]]

; CHECK: [[RETRY:.LBB[0-9]+_[0-9]+]]:

; CHECK:     ldaxp [[OLD_LO:x[0-9]+]], [[OLD_HI:x[0-9]+]], [x0]

; CHECK:     cmp [[OLD_LO]], [[DESIRED_LO]]

; CHECK:     sbcs xzr, [[OLD_HI]], [[DESIRED_HI]]

; CHECK:     b.ne [[DONE:.LBB[0-9]+_[0-9]+]]

; CHECK:     stlxp [[STATUS:w[0-9]+]], [[NEW_LO]], [[NEW_HI]], [x0]

; CHECK:     cbnz [[STATUS]], [[RETRY]]

; CHECK: [[DONE]]:



  %desired = load volatile i128, i128* @var128

  %new = load volatile i128, i128* @var128

  %val = cmpxchg i128* %addr, i128 %desired, i128 %new seq_cst seq_cst

  ret { i128, i1 } %val

}