Reimplement r114460 in target-independent DAGCombine rather than target-dependent, by using
the predicate to discover the number of sign bits. Enhance X86's target lowering to provide
a useful response to this query.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114473 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index ad9ef77..ab57353 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1021,7 +1021,6 @@
setTargetDAGCombine(ISD::OR);
setTargetDAGCombine(ISD::STORE);
setTargetDAGCombine(ISD::ZERO_EXTEND);
- setTargetDAGCombine(ISD::ADD);
if (Subtarget->is64Bit())
setTargetDAGCombine(ISD::MUL);
@@ -9980,6 +9979,16 @@
}
}
+unsigned X86TargetLowering::ComputeNumSignBitsForTargetNode(SDValue Op,
+ unsigned Depth) const {
+ // SETCC_CARRY sets the dest to ~0 for true or 0 for false.
+ if (Op.getOpcode() == X86ISD::SETCC_CARRY)
+ return Op.getValueType().getScalarType().getSizeInBits();
+
+ // Fallback case.
+ return 1;
+}
+
/// isGAPlusOffset - Returns true (and the GlobalValue and the offset) if the
/// node is a GlobalAddress + offset.
bool X86TargetLowering::isGAPlusOffset(SDNode *N,
@@ -10454,27 +10463,6 @@
return SDValue();
}
-/// PerformAddCombine - Optimize ADD when combined with X86 opcodes.
-static SDValue PerformAddCombine(SDNode *N, SelectionDAG &DAG,
- TargetLowering::DAGCombinerInfo &DCI) {
- if (DCI.isBeforeLegalize() || DCI.isCalledByLegalizer())
- return SDValue();
-
- EVT VT = N->getValueType(0);
- SDValue Op1 = N->getOperand(1);
- if (Op1->getOpcode() == ISD::AND) {
- SDValue AndOp0 = Op1->getOperand(0);
- ConstantSDNode *AndOp1 = dyn_cast<ConstantSDNode>(Op1->getOperand(1));
- // (add z, (and (sbbl x, x), 1)) -> (sub z, (sbbl x, x))
- if (AndOp0->getOpcode() == X86ISD::SETCC_CARRY &&
- AndOp1 && AndOp1->getZExtValue() == 1) {
- DebugLoc DL = N->getDebugLoc();
- return DAG.getNode(ISD::SUB, DL, VT, N->getOperand(0), AndOp0);
- }
- }
-
- return SDValue();
-}
/// PerformMulCombine - Optimize a single multiply with constant into two
/// in order to implement it with two cheaper instructions, e.g.
@@ -10961,7 +10949,6 @@
return PerformEXTRACT_VECTOR_ELTCombine(N, DAG, *this);
case ISD::SELECT: return PerformSELECTCombine(N, DAG, Subtarget);
case X86ISD::CMOV: return PerformCMOVCombine(N, DAG, DCI);
- case ISD::ADD: return PerformAddCombine(N, DAG, DCI);
case ISD::MUL: return PerformMulCombine(N, DAG, DCI);
case ISD::SHL:
case ISD::SRA: