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R600: Implement iterative algorithm for udivrem

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Initial implementation, rather slow

Patch by: Jan Vesely

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207588 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tom Stellard 2014-04-29 23:12:45 +00:00
parent dbe7f8723a
commit ea89cd8b52
1 changed files with 50 additions and 0 deletions
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50
lib/Target/R600/AMDGPUISelLowering.cpp
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@ -427,6 +427,56 @@ void AMDGPUTargetLowering::ReplaceNodeResults(SDNode *N,
Results.push_back(UDIVREM.getValue(1));
break;
}
case ISD::UDIVREM: {
SDValue Op = SDValue(N, 0);
SDLoc DL(Op);
EVT VT = Op.getValueType();
EVT HalfVT = VT.getHalfSizedIntegerVT(*DAG.getContext());
//HiLo split
SDValue LHS_Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT,
N->getOperand(0), DAG.getConstant(0, HalfVT));
SDValue LHS_Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, DL, HalfVT,
N->getOperand(0), DAG.getConstant(1, HalfVT));
SDValue RHS = N->getOperand(1);
SDValue DIV = DAG.getConstant(0, VT);
SDValue REM = DAG.getConstant(0, VT);
const unsigned bitWidth = VT.getSizeInBits();
const unsigned halfBitWidth = HalfVT.getSizeInBits();
SDValue one = DAG.getConstant(1, HalfVT);
SDValue one_VT = DAG.getConstant(1, VT);
for (unsigned i = 0; i < bitWidth; ++i) {
SDValue POS = DAG.getConstant((bitWidth - i - 1) % halfBitWidth, HalfVT);
// Get Value of high bit
SDValue HBit = DAG.getNode(ISD::SRL, DL, HalfVT,
i < halfBitWidth ? LHS_Hi : LHS_Lo, POS);
HBit = DAG.getNode(ISD::AND, DL, HalfVT, HBit, one);
HBit = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, HBit);
// Add the high bit to shifted remainder
REM = DAG.getNode(ISD::SHL, DL, VT, REM, one);
REM = DAG.getNode(ISD::OR, DL, VT, REM, HBit);
// Update DIV
SDValue ShDIV = DAG.getNode(ISD::SHL, DL, VT, DIV, one);
SDValue ShDIV_plus = DAG.getNode(ISD::OR, DL, VT, ShDIV, one_VT);
DIV = DAG.getSelectCC(DL, REM, RHS, ShDIV_plus, ShDIV, ISD::SETGE);
// Update REM
SDValue REM_sub = DAG.getNode(ISD::SUB, DL, VT, REM, RHS);
REM = DAG.getSelectCC(DL, REM, RHS, REM_sub, REM, ISD::SETGE);
}
Results.push_back(DIV);
Results.push_back(REM);
break;
}
default:
return;
}