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[SystemZ] Extend integer absolute selection

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This patch makes more use of LPGFR and LNGFR.  It builds on top of
the LTGFR selection from r197234.  Most of the tests are motivated
by what InstCombine would produce.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197236 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Sandiford
2013-12-13 15:35:00 +00:00
parent 467a3f9b3f
commit 193bf3171f
6 changed files with 252 additions and 4 deletions
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38
lib/Target/SystemZ/SystemZISelLowering.cpp
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@@ -1622,6 +1622,28 @@ SDValue SystemZTargetLowering::lowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
DAG.getConstant(C.CCMask, MVT::i32), Dest, Glue);
}
// Return true if Pos is CmpOp and Neg is the negative of CmpOp,
// allowing Pos and Neg to be wider than CmpOp.
static bool isAbsolute(SDValue CmpOp, SDValue Pos, SDValue Neg) {
return (Neg.getOpcode() == ISD::SUB &&
Neg.getOperand(0).getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(Neg.getOperand(0))->getZExtValue() == 0 &&
Neg.getOperand(1) == Pos &&
(Pos == CmpOp ||
(Pos.getOpcode() == ISD::SIGN_EXTEND &&
Pos.getOperand(0) == CmpOp)));
}
// Return the absolute or negative absolute of Op; IsNegative decides which.
static SDValue getAbsolute(SelectionDAG &DAG, SDLoc DL, SDValue Op,
bool IsNegative) {
Op = DAG.getNode(SystemZISD::IABS, DL, Op.getValueType(), Op);
if (IsNegative)
Op = DAG.getNode(ISD::SUB, DL, Op.getValueType(),
DAG.getConstant(0, Op.getValueType()), Op);
return Op;
}
SDValue SystemZTargetLowering::lowerSELECT_CC(SDValue Op,
SelectionDAG &DAG) const {
SDValue CmpOp0 = Op.getOperand(0);
@@ -1632,6 +1654,21 @@ SDValue SystemZTargetLowering::lowerSELECT_CC(SDValue Op,
SDLoc DL(Op);
Comparison C(getCmp(DAG, CmpOp0, CmpOp1, CC));
// Check for absolute and negative-absolute selections, including those
// where the comparison value is sign-extended (for LPGFR and LNGFR).
// This check supplements the one in DAGCombiner.
if (C.Opcode == SystemZISD::ICMP &&
C.CCMask != SystemZ::CCMASK_CMP_EQ &&
C.CCMask != SystemZ::CCMASK_CMP_NE &&
C.Op1.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(C.Op1)->getZExtValue() == 0) {
if (isAbsolute(C.Op0, TrueOp, FalseOp))
return getAbsolute(DAG, DL, TrueOp, C.CCMask & SystemZ::CCMASK_CMP_LT);
if (isAbsolute(C.Op0, FalseOp, TrueOp))
return getAbsolute(DAG, DL, FalseOp, C.CCMask & SystemZ::CCMASK_CMP_GT);
}
SDValue Glue = emitCmp(DAG, DL, C);
// Special case for handling -1/0 results. The shifts we use here
@@ -2324,6 +2361,7 @@ const char *SystemZTargetLowering::getTargetNodeName(unsigned Opcode) const {
OPCODE(SIBCALL);
OPCODE(PCREL_WRAPPER);
OPCODE(PCREL_OFFSET);
OPCODE(IABS);
OPCODE(ICMP);
OPCODE(FCMP);
OPCODE(TM);