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| author | Anton Korobeynikov <asl@math.spbu.ru> | 2012-03-19 19:19:50 +0000 |
|---|---|---|
| committer | Anton Korobeynikov <asl@math.spbu.ru> | 2012-03-19 19:19:50 +0000 |
| commit | 2d7ea04e2822bbe5faad0eefceb7a300ea01224e (patch) | |
| tree | d37e72d8497c9880c5764f35ae50eecc738b2a8a /lib | |
| parent | 23f1cbbd686513ae5defbd3afdf5e286befe8a76 (diff) | |
| download | external_llvm-2d7ea04e2822bbe5faad0eefceb7a300ea01224e.tar.gz external_llvm-2d7ea04e2822bbe5faad0eefceb7a300ea01224e.tar.bz2 external_llvm-2d7ea04e2822bbe5faad0eefceb7a300ea01224e.zip | |
Perform mul combine when multiplying wiht negative constants.
Patch by Weiming Zhao!
This fixes PR12212
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153049 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/ARM/ARMISelLowering.cpp | 66 |
1 files changed, 48 insertions, 18 deletions
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp index 459d82cdbe..e26dd22c92 100644 --- a/lib/Target/ARM/ARMISelLowering.cpp +++ b/lib/Target/ARM/ARMISelLowering.cpp @@ -6865,33 +6865,63 @@ static SDValue PerformMULCombine(SDNode *N, if (!C) return SDValue(); - uint64_t MulAmt = C->getZExtValue(); + int64_t MulAmt = C->getSExtValue(); unsigned ShiftAmt = CountTrailingZeros_64(MulAmt); + ShiftAmt = ShiftAmt & (32 - 1); SDValue V = N->getOperand(0); DebugLoc DL = N->getDebugLoc(); SDValue Res; MulAmt >>= ShiftAmt; - if (isPowerOf2_32(MulAmt - 1)) { - // (mul x, 2^N + 1) => (add (shl x, N), x) - Res = DAG.getNode(ISD::ADD, DL, VT, - V, DAG.getNode(ISD::SHL, DL, VT, - V, DAG.getConstant(Log2_32(MulAmt-1), - MVT::i32))); - } else if (isPowerOf2_32(MulAmt + 1)) { - // (mul x, 2^N - 1) => (sub (shl x, N), x) - Res = DAG.getNode(ISD::SUB, DL, VT, - DAG.getNode(ISD::SHL, DL, VT, - V, DAG.getConstant(Log2_32(MulAmt+1), - MVT::i32)), - V); - } else - return SDValue(); + + if (MulAmt >= 0) { + if (isPowerOf2_32(MulAmt - 1)) { + // (mul x, 2^N + 1) => (add (shl x, N), x) + Res = DAG.getNode(ISD::ADD, DL, VT, + V, + DAG.getNode(ISD::SHL, DL, VT, + V, + DAG.getConstant(Log2_32(MulAmt - 1), + MVT::i32))); + } else if (isPowerOf2_32(MulAmt + 1)) { + // (mul x, 2^N - 1) => (sub (shl x, N), x) + Res = DAG.getNode(ISD::SUB, DL, VT, + DAG.getNode(ISD::SHL, DL, VT, + V, + DAG.getConstant(Log2_32(MulAmt + 1), + MVT::i32)), + V); + } else + return SDValue(); + } else { + uint64_t MulAmtAbs = -MulAmt; + if (isPowerOf2_32(MulAmtAbs + 1)) { + // (mul x, -(2^N - 1)) => (sub x, (shl x, N)) + Res = DAG.getNode(ISD::SUB, DL, VT, + V, + DAG.getNode(ISD::SHL, DL, VT, + V, + DAG.getConstant(Log2_32(MulAmtAbs + 1), + MVT::i32))); + } else if (isPowerOf2_32(MulAmtAbs - 1)) { + // (mul x, -(2^N + 1)) => - (add (shl x, N), x) + Res = DAG.getNode(ISD::ADD, DL, VT, + V, + DAG.getNode(ISD::SHL, DL, VT, + V, + DAG.getConstant(Log2_32(MulAmtAbs-1), + MVT::i32))); + Res = DAG.getNode(ISD::SUB, DL, VT, + DAG.getConstant(0, MVT::i32),Res); + + } else + return SDValue(); + } if (ShiftAmt != 0) - Res = DAG.getNode(ISD::SHL, DL, VT, Res, - DAG.getConstant(ShiftAmt, MVT::i32)); + Res = DAG.getNode(ISD::SHL, DL, VT, + Res, DAG.getConstant(ShiftAmt, MVT::i32)); // Do not add new nodes to DAG combiner worklist. DCI.CombineTo(N, Res, false); |