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Pull in r326882 from upstream llvm trunk (by Sjoerd Meijer):
[ARM] Fix for PR36577 Don't PerformSHLSimplify if the given node is used by a node that also uses a constant because we may get stuck in an infinite combine loop. bugzilla: https://bugs.llvm.org/show_bug.cgi?id=36577 Patch by Sam Parker. Differential Revision: https://reviews.llvm.org/D44097 This fixes a hang when compiling one particular file in java/openjdk8 for armv6 and armv7. Reported by: swills PR: 226388
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=330686
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@ -10201,7 +10201,14 @@ static SDValue PerformSHLSimplify(SDNode *N,
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case ISD::XOR:
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case ISD::SETCC:
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case ARMISD::CMP:
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// Check that its not already using a shl.
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// Check that the user isn't already using a constant because there
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// aren't any instructions that support an immediate operand and a
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// shifted operand.
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if (isa<ConstantSDNode>(U->getOperand(0)) ||
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isa<ConstantSDNode>(U->getOperand(1)))
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return SDValue();
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// Check that it's not already using a shift.
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if (U->getOperand(0).getOpcode() == ISD::SHL ||
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U->getOperand(1).getOpcode() == ISD::SHL)
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return SDValue();
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@ -10223,8 +10230,6 @@ static SDValue PerformSHLSimplify(SDNode *N,
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if (!C1ShlC2 || !C2)
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return SDValue();
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DEBUG(dbgs() << "Trying to simplify shl: "; N->dump());
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APInt C2Int = C2->getAPIntValue();
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APInt C1Int = C1ShlC2->getAPIntValue();
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@ -10238,12 +10243,12 @@ static SDValue PerformSHLSimplify(SDNode *N,
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C1Int.lshrInPlace(C2Int);
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// The immediates are encoded as an 8-bit value that can be rotated.
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unsigned Zeros = C1Int.countLeadingZeros() + C1Int.countTrailingZeros();
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if (C1Int.getBitWidth() - Zeros > 8)
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return SDValue();
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auto LargeImm = [](const APInt &Imm) {
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unsigned Zeros = Imm.countLeadingZeros() + Imm.countTrailingZeros();
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return Imm.getBitWidth() - Zeros > 8;
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};
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Zeros = C2Int.countLeadingZeros() + C2Int.countTrailingZeros();
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if (C2Int.getBitWidth() - Zeros > 8)
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if (LargeImm(C1Int) || LargeImm(C2Int))
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return SDValue();
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SelectionDAG &DAG = DCI.DAG;
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@ -10254,6 +10259,10 @@ static SDValue PerformSHLSimplify(SDNode *N,
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// Shift left to compensate for the lshr of C1Int.
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SDValue Res = DAG.getNode(ISD::SHL, dl, MVT::i32, BinOp, SHL.getOperand(1));
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DEBUG(dbgs() << "Simplify shl use:\n"; SHL.getOperand(0).dump(); SHL.dump();
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N->dump());
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DEBUG(dbgs() << "Into:\n"; X.dump(); BinOp.dump(); Res.dump());
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DAG.ReplaceAllUsesWith(SDValue(N, 0), Res);
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return SDValue(N, 0);
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}
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