[X86] Cleanup FCOPYSIGN lowering. NFC intended.

llvm-svn: 223542

1 files changed, 15 insertions, 29 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f1384116638..8fa01465268 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -14461,19 +14461,17 @@ static SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) {
   // At this point the operands and the result should have the same
   // type, and that won't be f80 since that is not custom lowered.
 
-  // First get the sign bit of second operand.
-  SmallVector<Constant*,4> CV;
-  if (SrcVT == MVT::f64) {
-    const fltSemantics &Sem = APFloat::IEEEdouble;
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(64, 1ULL << 63))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(64, 0))));
-  } else {
-    const fltSemantics &Sem = APFloat::IEEEsingle;
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 1U << 31))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-  }
+  const fltSemantics &Sem =
+      VT == MVT::f64 ? APFloat::IEEEdouble : APFloat::IEEEsingle;
+  const unsigned SizeInBits = VT.getSizeInBits();
+
+  SmallVector<Constant *, 4> CV(
+      VT == MVT::f64 ? 2 : 4,
+      ConstantFP::get(*Context, APFloat(Sem, APInt(SizeInBits, 0))));
+
+  // First, clear all bits but the sign bit from the second operand (sign).
+  CV[0] = ConstantFP::get(*Context,
+                          APFloat(Sem, APInt::getHighBitsSet(SizeInBits, 1)));
   Constant *C = ConstantVector::get(CV);
   SDValue CPIdx = DAG.getConstantPool(C, TLI.getPointerTy(), 16);
   SDValue Mask1 = DAG.getLoad(SrcVT, dl, DAG.getEntryNode(), CPIdx,
@@ -14481,21 +14479,9 @@ static SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) {
                               false, false, false, 16);
   SDValue SignBit = DAG.getNode(X86ISD::FAND, dl, SrcVT, Op1, Mask1);
 
-  // Clear first operand sign bit.
-  CV.clear();
-  if (VT == MVT::f64) {
-    const fltSemantics &Sem = APFloat::IEEEdouble;
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem,
-                                                   APInt(64, ~(1ULL << 63)))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(64, 0))));
-  } else {
-    const fltSemantics &Sem = APFloat::IEEEsingle;
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem,
-                                                   APInt(32, ~(1U << 31)))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-    CV.push_back(ConstantFP::get(*Context, APFloat(Sem, APInt(32, 0))));
-  }
+  // Next, clear the sign bit from the first operand (magnitude).
+  CV[0] = ConstantFP::get(
+      *Context, APFloat(Sem, APInt::getLowBitsSet(SizeInBits, SizeInBits - 1)));
   C = ConstantVector::get(CV);
   CPIdx = DAG.getConstantPool(C, TLI.getPointerTy(), 16);
   SDValue Mask2 = DAG.getLoad(VT, dl, DAG.getEntryNode(), CPIdx,
@@ -14503,7 +14489,7 @@ static SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) {
                               false, false, false, 16);
   SDValue Val = DAG.getNode(X86ISD::FAND, dl, VT, Op0, Mask2);
 
-  // Or the value with the sign bit.
+  // OR the magnitude value with the sign bit.
   return DAG.getNode(X86ISD::FOR, dl, VT, Val, SignBit);
 }