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Fixed version of optimized integer divide is now fixed. Calculate the

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quotient, not the remainder.  Also, make sure to remove the old div operand
from the ExprMap and let SelectExpr insert the new one.

llvm-svn: 21111
This commit is contained in:
Nate Begeman 2005-04-06 06:44:57 +00:00
parent 2db29b8016
commit 98251d6a1c
1 changed files with 9 additions and 13 deletions
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22
lib/Target/PowerPC/PPC32ISelPattern.cpp
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@ -551,7 +551,7 @@ static unsigned getImmediateForOpcode(SDOperand N, unsigned Opcode,
if (v <= -2 || v >= 2) { return 4; }
break;
case ISD::UDIV:
if (v != 0) { return 4; }
if (v > 1) { return 4; }
break;
}
return 0;
@ -711,10 +711,7 @@ SDOperand ISel::BuildSDIVSequence(SDOperand N) {
// Extract the sign bit and add it to the quotient
SDOperand T =
ISelDAG->getNode(ISD::SRL, MVT::i32, Q, ISelDAG->getConstant(31, MVT::i32));
Q = ISelDAG->getNode(ISD::ADD, MVT::i32, Q, T);
// Compute the remainder
T = ISelDAG->getNode(ISD::MUL, MVT::i32, Q, N.getOperand(1));
return ISelDAG->getNode(ISD::SUB, MVT::i32, N.getOperand(0), T);
return ISelDAG->getNode(ISD::ADD, MVT::i32, Q, T);
}
/// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant,
@ -739,9 +736,7 @@ SDOperand ISel::BuildUDIVSequence(SDOperand N) {
Q = ISelDAG->getNode(ISD::SRL, MVT::i32, NPQ,
ISelDAG->getConstant(magics.s-1, MVT::i32));
}
// Compute the remainder
SDOperand T = ISelDAG->getNode(ISD::MUL, MVT::i32, Q, N.getOperand(1));
return ISelDAG->getNode(ISD::SUB, MVT::i32, N.getOperand(0), T);
return Q;
}
/// getGlobalBaseReg - Output the instructions required to put the
@ -1601,11 +1596,12 @@ unsigned ISel::SelectExpr(SDOperand N) {
return Result;
// If this is a divide by constant, we can emit code using some magic
// constants to implement it as a multiply instead.
//case 4:
// if (opcode == ISD::SDIV)
// return SelectExpr(BuildSDIVSequence(N));
// else
// return SelectExpr(BuildUDIVSequence(N));
case 4:
ExprMap.erase(N);
if (opcode == ISD::SDIV)
return SelectExpr(BuildSDIVSequence(N));
else
return SelectExpr(BuildUDIVSequence(N));
}
Tmp1 = SelectExpr(N.getOperand(0));
Tmp2 = SelectExpr(N.getOperand(1));