[x86] fix formatting; NFC

This should really be generalized to allow increment and/or
we should replace it by using ISD::matchUnaryPredicate().
See D55515 for context.

llvm-svn: 348776

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a9bc93f..e82a79f 100644 (file)
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -19148,34 +19148,32 @@ static SDValue LowerIntVSETCC_AVX512(SDValue Op, SelectionDAG &DAG) {
   return DAG.getSetCC(dl, VT, Op0, Op1, SetCCOpcode);
 }
 
-/// Try to turn a VSETULT into a VSETULE by modifying its second
-/// operand \p Op1.  If non-trivial (for example because it's not constant)
-/// return an empty value.
-static SDValue ChangeVSETULTtoVSETULE(const SDLoc &dl, SDValue Op1,
-                                      SelectionDAG &DAG) {
-  BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(Op1.getNode());
+/// Given a simple buildvector constant, return a new vector constant with each
+/// element decremented. If decrementing would result in underflow or this
+/// is not a simple vector constant, return an empty value.
+static SDValue decrementVectorConstant(SDValue V, SelectionDAG &DAG) {
+  auto *BV = dyn_cast<BuildVectorSDNode>(V.getNode());
   if (!BV)
     return SDValue();
 
-  MVT VT = Op1.getSimpleValueType();
-  MVT EVT = VT.getVectorElementType();
-  unsigned n = VT.getVectorNumElements();
-  SmallVector<SDValue, 8> ULTOp1;
-
-  for (unsigned i = 0; i < n; ++i) {
-    ConstantSDNode *Elt = dyn_cast<ConstantSDNode>(BV->getOperand(i));
-    if (!Elt || Elt->isOpaque() || Elt->getSimpleValueType(0) != EVT)
+  MVT VT = V.getSimpleValueType();
+  MVT EltVT = VT.getVectorElementType();
+  unsigned NumElts = VT.getVectorNumElements();
+  SmallVector<SDValue, 8> NewVecC;
+  SDLoc DL(V);
+  for (unsigned i = 0; i < NumElts; ++i) {
+    auto *Elt = dyn_cast<ConstantSDNode>(BV->getOperand(i));
+    if (!Elt || Elt->isOpaque() || Elt->getSimpleValueType(0) != EltVT)
       return SDValue();
 
     // Avoid underflow.
-    APInt Val = Elt->getAPIntValue();
-    if (Val == 0)
+    if (Elt->getAPIntValue().isNullValue())
       return SDValue();
 
-    ULTOp1.push_back(DAG.getConstant(Val - 1, dl, EVT));
+    NewVecC.push_back(DAG.getConstant(Elt->getAPIntValue() - 1, DL, EltVT));
   }
 
-  return DAG.getBuildVector(VT, dl, ULTOp1);
+  return DAG.getBuildVector(VT, DL, NewVecC);
 }
 
 /// As another special case, use PSUBUS[BW] when it's profitable. E.g. for
@@ -19204,7 +19202,7 @@ static SDValue LowerVSETCCWithSUBUS(SDValue Op0, SDValue Op1, MVT VT,
     // Only do this pre-AVX since vpcmp* is no longer destructive.
     if (Subtarget.hasAVX())
       return SDValue();
-    SDValue ULEOp1 = ChangeVSETULTtoVSETULE(dl, Op1, DAG);
+    SDValue ULEOp1 = decrementVectorConstant(Op1, DAG);
     if (!ULEOp1)
       return SDValue();
     Op1 = ULEOp1;