Implement flt_rounds for PowerPC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46174 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 20e2632..87f101d 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -109,6 +109,8 @@
setOperationAction(ISD::FCOS , MVT::f32, Expand);
setOperationAction(ISD::FREM , MVT::f32, Expand);
setOperationAction(ISD::FPOW , MVT::f32, Expand);
+
+ setOperationAction(ISD::FLT_ROUNDS, MVT::i32, Custom);
// If we're enabling GP optimizations, use hardware square root
if (!TM.getSubtarget<PPCSubtarget>().hasFSQRT()) {
@@ -2207,6 +2209,67 @@
return FP;
}
+static SDOperand LowerFLT_ROUNDS(SDOperand Op, SelectionDAG &DAG) {
+ /*
+ The rounding mode is in bits 30:31 of FPSR, and has the following
+ settings:
+ 00 Round to nearest
+ 01 Round to 0
+ 10 Round to +inf
+ 11 Round to -inf
+
+ FLT_ROUNDS, on the other hand, expects the following:
+ -1 Undefined
+ 0 Round to 0
+ 1 Round to nearest
+ 2 Round to +inf
+ 3 Round to -inf
+
+ To perform the conversion, we do:
+ ((FPSCR & 0x3) ^ ((~FPSCR & 0x3) >> 1))
+ */
+
+ MachineFunction &MF = DAG.getMachineFunction();
+ MVT::ValueType VT = Op.getValueType();
+ MVT::ValueType PtrVT = DAG.getTargetLoweringInfo().getPointerTy();
+ std::vector<MVT::ValueType> NodeTys;
+ SDOperand MFFSreg, InFlag;
+
+ // Save FP Control Word to register
+ NodeTys.push_back(MVT::f64); // return register
+ NodeTys.push_back(MVT::Flag); // unused in this context
+ SDOperand Chain = DAG.getNode(PPCISD::MFFS, NodeTys, &InFlag, 0);
+
+ // Save FP register to stack slot
+ int SSFI = MF.getFrameInfo()->CreateStackObject(8, 8);
+ SDOperand StackSlot = DAG.getFrameIndex(SSFI, PtrVT);
+ SDOperand Store = DAG.getStore(DAG.getEntryNode(), Chain,
+ StackSlot, NULL, 0);
+
+ // Load FP Control Word from low 32 bits of stack slot.
+ SDOperand Four = DAG.getConstant(4, PtrVT);
+ SDOperand Addr = DAG.getNode(ISD::ADD, PtrVT, StackSlot, Four);
+ SDOperand CWD = DAG.getLoad(MVT::i32, Store, Addr, NULL, 0);
+
+ // Transform as necessary
+ SDOperand CWD1 =
+ DAG.getNode(ISD::AND, MVT::i32,
+ CWD, DAG.getConstant(3, MVT::i32));
+ SDOperand CWD2 =
+ DAG.getNode(ISD::SRL, MVT::i32,
+ DAG.getNode(ISD::AND, MVT::i32,
+ DAG.getNode(ISD::XOR, MVT::i32,
+ CWD, DAG.getConstant(3, MVT::i32)),
+ DAG.getConstant(3, MVT::i32)),
+ DAG.getConstant(1, MVT::i8));
+
+ SDOperand RetVal =
+ DAG.getNode(ISD::XOR, MVT::i32, CWD1, CWD2);
+
+ return DAG.getNode((MVT::getSizeInBits(VT) < 16 ?
+ ISD::TRUNCATE : ISD::ZERO_EXTEND), VT, RetVal);
+}
+
static SDOperand LowerSHL_PARTS(SDOperand Op, SelectionDAG &DAG) {
assert(Op.getNumOperands() == 3 && Op.getValueType() == MVT::i32 &&
Op.getOperand(1).getValueType() == MVT::i32 && "Unexpected SHL!");
@@ -3027,6 +3090,7 @@
case ISD::FP_TO_SINT: return LowerFP_TO_SINT(Op, DAG);
case ISD::SINT_TO_FP: return LowerSINT_TO_FP(Op, DAG);
case ISD::FP_ROUND_INREG: return LowerFP_ROUND_INREG(Op, DAG);
+ case ISD::FLT_ROUNDS: return LowerFLT_ROUNDS(Op, DAG);
// Lower 64-bit shifts.
case ISD::SHL_PARTS: return LowerSHL_PARTS(Op, DAG);