Lower setcc branchless, if this is profitable.
Based on the patch by Brian Lucas!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91175 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/MSP430/MSP430ISelLowering.cpp b/lib/Target/MSP430/MSP430ISelLowering.cpp
index 5012791d3..4bd6006 100644
--- a/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -115,8 +115,8 @@
setOperationAction(ISD::BR_CC, MVT::i8, Custom);
setOperationAction(ISD::BR_CC, MVT::i16, Custom);
setOperationAction(ISD::BRCOND, MVT::Other, Expand);
- setOperationAction(ISD::SETCC, MVT::i8, Expand);
- setOperationAction(ISD::SETCC, MVT::i16, Expand);
+ setOperationAction(ISD::SETCC, MVT::i8, Custom);
+ setOperationAction(ISD::SETCC, MVT::i16, Custom);
setOperationAction(ISD::SELECT, MVT::i8, Expand);
setOperationAction(ISD::SELECT, MVT::i16, Expand);
setOperationAction(ISD::SELECT_CC, MVT::i8, Custom);
@@ -183,6 +183,7 @@
case ISD::SRA: return LowerShifts(Op, DAG);
case ISD::GlobalAddress: return LowerGlobalAddress(Op, DAG);
case ISD::ExternalSymbol: return LowerExternalSymbol(Op, DAG);
+ case ISD::SETCC: return LowerSETCC(Op, DAG);
case ISD::BR_CC: return LowerBR_CC(Op, DAG);
case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
case ISD::SIGN_EXTEND: return LowerSIGN_EXTEND(Op, DAG);
@@ -701,6 +702,88 @@
Chain, Dest, TargetCC, Flag);
}
+
+SDValue MSP430TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) {
+ SDValue LHS = Op.getOperand(0);
+ SDValue RHS = Op.getOperand(1);
+ DebugLoc dl = Op.getDebugLoc();
+
+ // If we are doing an AND and testing against zero, then the CMP
+ // will not be generated. The AND (or BIT) will generate the condition codes,
+ // but they are different from CMP.
+ bool andCC = false;
+ if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(RHS)) {
+ if (RHSC->isNullValue() && LHS.hasOneUse() &&
+ (LHS.getOpcode() == ISD::AND ||
+ (LHS.getOpcode() == ISD::TRUNCATE &&
+ LHS.getOperand(0).getOpcode() == ISD::AND))) {
+ andCC = true;
+ }
+ }
+ ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
+ SDValue TargetCC;
+ SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
+
+ // Get the condition codes directly from the status register, if its easy.
+ // Otherwise a branch will be generated. Note that the AND and BIT
+ // instructions generate different flags than CMP, the carry bit can be used
+ // for NE/EQ.
+ bool Invert = false;
+ bool Shift = false;
+ bool Convert = true;
+ switch (cast<ConstantSDNode>(TargetCC)->getZExtValue()) {
+ default:
+ Convert = false;
+ break;
+ case MSP430CC::COND_HS:
+ // Res = SRW & 1, no processing is required
+ break;
+ case MSP430CC::COND_LO:
+ // Res = ~(SRW & 1)
+ Invert = true;
+ break;
+ case MSP430CC::COND_NE:
+ if (andCC) {
+ // C = ~Z, thus Res = SRW & 1, no processing is required
+ } else {
+ // Res = (SRW >> 1) & 1
+ Shift = true;
+ }
+ break;
+ case MSP430CC::COND_E:
+ if (andCC) {
+ // C = ~Z, thus Res = ~(SRW & 1)
+ } else {
+ // Res = ~((SRW >> 1) & 1)
+ Shift = true;
+ }
+ Invert = true;
+ break;
+ }
+ EVT VT = Op.getValueType();
+ SDValue One = DAG.getConstant(1, VT);
+ if (Convert) {
+ SDValue SR = DAG.getCopyFromReg(DAG.getEntryNode(), dl, MSP430::SRW,
+ MVT::i16, Flag);
+ if (Shift)
+ // FIXME: somewhere this is turned into a SRL, lower it MSP specific?
+ SR = DAG.getNode(ISD::SRA, dl, MVT::i16, SR, One);
+ SR = DAG.getNode(ISD::AND, dl, MVT::i16, SR, One);
+ if (Invert)
+ SR = DAG.getNode(ISD::XOR, dl, MVT::i16, SR, One);
+ return SR;
+ } else {
+ SDValue Zero = DAG.getConstant(0, VT);
+ SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Flag);
+ SmallVector<SDValue, 4> Ops;
+ Ops.push_back(One);
+ Ops.push_back(Zero);
+ Ops.push_back(TargetCC);
+ Ops.push_back(Flag);
+ return DAG.getNode(MSP430ISD::SELECT_CC, dl, VTs, &Ops[0], Ops.size());
+ }
+}
+
SDValue MSP430TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) {
SDValue LHS = Op.getOperand(0);
SDValue RHS = Op.getOperand(1);