Fix typo.

[oota-llvm.git] / lib / CodeGen / SelectionDAG / FastISel.cpp

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index 5b4c79a9fd92d8a995531057256ccbe431acbd3a..54544a4d1499eebf13fc44e4428f42f54909a196 100644 (file)
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -608,6 +608,49 @@ FastISel::FastEmitBranch(MachineBasicBlock *MSucc) {
   MBB->addSuccessor(MSucc);
 }
 
+/// SelectFNeg - Emit an FNeg operation.
+///
+bool
+FastISel::SelectFNeg(User *I) {
+  unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I));
+  if (OpReg == 0) return false;
+
+  // If the target has ISD::FNEG, use it.
+  EVT VT = TLI.getValueType(I->getType());
+  unsigned ResultReg = FastEmit_r(VT.getSimpleVT(), VT.getSimpleVT(),
+                                  ISD::FNEG, OpReg);
+  if (ResultReg != 0) {
+    UpdateValueMap(I, ResultReg);
+    return true;
+  }
+
+  // Bitcast the value to integer, twiddle the sign bit with xor,
+  // and then bitcast it back to floating-point.
+  if (VT.getSizeInBits() > 64) return false;
+  EVT IntVT = EVT::getIntegerVT(I->getContext(), VT.getSizeInBits());
+  if (!TLI.isTypeLegal(IntVT))
+    return false;
+
+  unsigned IntReg = FastEmit_r(VT.getSimpleVT(), IntVT.getSimpleVT(),
+                               ISD::BIT_CONVERT, OpReg);
+  if (IntReg == 0)
+    return false;
+
+  unsigned IntResultReg = FastEmit_ri_(IntVT.getSimpleVT(), ISD::XOR, IntReg,
+                                       UINT64_C(1) << (VT.getSizeInBits()-1),
+                                       IntVT.getSimpleVT());
+  if (IntResultReg == 0)
+    return false;
+
+  ResultReg = FastEmit_r(IntVT.getSimpleVT(), VT.getSimpleVT(),
+                         ISD::BIT_CONVERT, IntResultReg);
+  if (ResultReg == 0)
+    return false;
+
+  UpdateValueMap(I, ResultReg);
+  return true;
+}
+
 bool
 FastISel::SelectOperator(User *I, unsigned Opcode) {
   switch (Opcode) {
@@ -618,6 +661,9 @@ FastISel::SelectOperator(User *I, unsigned Opcode) {
   case Instruction::Sub:
     return SelectBinaryOp(I, ISD::SUB);
   case Instruction::FSub:
+    // FNeg is currently represented in LLVM IR as a special case of FSub.
+    if (BinaryOperator::isFNeg(I))
+      return SelectFNeg(I);
     return SelectBinaryOp(I, ISD::FSUB);
   case Instruction::Mul:
     return SelectBinaryOp(I, ISD::MUL);