Simplify: truncate ({zero|sign}_extend (X))

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19353 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-07 21:56:24 +00:00
parent 03c0cf822e
commit fd8c39b773

View File

@ -428,6 +428,15 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
if (Operand.getValueType() == VT) return Operand; // noop truncate
if (OpOpcode == ISD::TRUNCATE)
return getNode(ISD::TRUNCATE, VT, Operand.Val->getOperand(0));
else if (OpOpcode == ISD::ZERO_EXTEND || OpOpcode == ISD::SIGN_EXTEND) {
// If the source is smaller than the dest, we still need an extend.
if (Operand.Val->getOperand(0).getValueType() < VT)
return getNode(OpOpcode, VT, Operand.Val->getOperand(0));
else if (Operand.Val->getOperand(0).getValueType() > VT)
return getNode(ISD::TRUNCATE, VT, Operand.Val->getOperand(0));
else
return Operand.Val->getOperand(0);
}
break;
}