SelectionDAG: Factor FP_TO_SINT lower code out of DAGLegalizer
Move the code to a helper function to allow calls from TypeLegalizer.
No functionality change intended
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Tom Stellard <tom@stellard.net>
Reviewed-by: Owen Anderson <resistor@mac.com>
llvm-svn: 212772
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 42372a2..05ace41 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2885,3 +2885,65 @@
}
return false;
}
+
+bool TargetLowering::expandFP_TO_SINT(SDNode *Node, SDValue &Result,
+ SelectionDAG &DAG) const {
+ EVT VT = Node->getOperand(0).getValueType();
+ EVT NVT = Node->getValueType(0);
+ SDLoc dl(SDValue(Node, 0));
+
+ // FIXME: Only f32 to i64 conversions are supported.
+ if (VT != MVT::f32 || NVT != MVT::i64)
+ return false;
+
+ // Expand f32 -> i64 conversion
+ // This algorithm comes from compiler-rt's implementation of fixsfdi:
+ // https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/fixsfdi.c
+ EVT IntVT = EVT::getIntegerVT(*DAG.getContext(),
+ VT.getSizeInBits());
+ SDValue ExponentMask = DAG.getConstant(0x7F800000, IntVT);
+ SDValue ExponentLoBit = DAG.getConstant(23, IntVT);
+ SDValue Bias = DAG.getConstant(127, IntVT);
+ SDValue SignMask = DAG.getConstant(APInt::getSignBit(VT.getSizeInBits()),
+ IntVT);
+ SDValue SignLowBit = DAG.getConstant(VT.getSizeInBits() - 1, IntVT);
+ SDValue MantissaMask = DAG.getConstant(0x007FFFFF, IntVT);
+
+ SDValue Bits = DAG.getNode(ISD::BITCAST, dl, IntVT, Node->getOperand(0));
+
+ SDValue ExponentBits = DAG.getNode(ISD::SRL, dl, IntVT,
+ DAG.getNode(ISD::AND, dl, IntVT, Bits, ExponentMask),
+ DAG.getZExtOrTrunc(ExponentLoBit, dl, getShiftAmountTy(IntVT)));
+ SDValue Exponent = DAG.getNode(ISD::SUB, dl, IntVT, ExponentBits, Bias);
+
+ SDValue Sign = DAG.getNode(ISD::SRA, dl, IntVT,
+ DAG.getNode(ISD::AND, dl, IntVT, Bits, SignMask),
+ DAG.getZExtOrTrunc(SignLowBit, dl, getShiftAmountTy(IntVT)));
+ Sign = DAG.getSExtOrTrunc(Sign, dl, NVT);
+
+ SDValue R = DAG.getNode(ISD::OR, dl, IntVT,
+ DAG.getNode(ISD::AND, dl, IntVT, Bits, MantissaMask),
+ DAG.getConstant(0x00800000, IntVT));
+
+ R = DAG.getZExtOrTrunc(R, dl, NVT);
+
+
+ R = DAG.getSelectCC(dl, Exponent, ExponentLoBit,
+ DAG.getNode(ISD::SHL, dl, NVT, R,
+ DAG.getZExtOrTrunc(
+ DAG.getNode(ISD::SUB, dl, IntVT, Exponent, ExponentLoBit),
+ dl, getShiftAmountTy(IntVT))),
+ DAG.getNode(ISD::SRL, dl, NVT, R,
+ DAG.getZExtOrTrunc(
+ DAG.getNode(ISD::SUB, dl, IntVT, ExponentLoBit, Exponent),
+ dl, getShiftAmountTy(IntVT))),
+ ISD::SETGT);
+
+ SDValue Ret = DAG.getNode(ISD::SUB, dl, NVT,
+ DAG.getNode(ISD::XOR, dl, NVT, R, Sign),
+ Sign);
+
+ Result = DAG.getSelectCC(dl, Exponent, DAG.getConstant(0, IntVT),
+ DAG.getConstant(0, NVT), Ret, ISD::SETLT);
+ return true;
+}