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

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 c0e9adf3cc
commit 39ef2f1d43
1 changed files with 9 additions and 13 deletions
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22
llvm/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));