[X86] Remove portions of r275950 that are no longer needed with i1 not being a legal type

Summary:
r275950 added support for turning (trunc (X >> N) to i1) into BT(X, N). But that's no longer necessary now that i1 isn't legal.

This patch removes the support for that, but preserves some of the refactorings done in that commit.

Reviewers: guyblank, RKSimon, spatel, zvi

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37673

llvm-svn: 312925

Author: topperc

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -16959,6 +16959,7 @@ static SDValue getBitTestCondition(SDValue Src, SDValue BitNo, ISD::CondCode CC,
 /// Result of 'and' is compared against zero. Change to a BT node if possible.
 static SDValue LowerAndToBT(SDValue And, ISD::CondCode CC,
                             const SDLoc &dl, SelectionDAG &DAG) {
+  assert(And.getOpcode() == ISD::AND && "Expected AND node!");
   SDValue Op0 = And.getOperand(0);
   SDValue Op1 = And.getOperand(1);
   if (Op0.getOpcode() == ISD::TRUNCATE)
@@ -17007,32 +17008,6 @@ static SDValue LowerAndToBT(SDValue And, ISD::CondCode CC,
   return SDValue();
 }
 
-// Convert (truncate (srl X, N) to i1) to (bt X, N)
-static SDValue LowerTruncateToBT(SDValue Op, ISD::CondCode CC,
-                                 const SDLoc &dl, SelectionDAG &DAG) {
-
-  assert(Op.getOpcode() == ISD::TRUNCATE && Op.getValueType() == MVT::i1 &&
-         "Expected TRUNCATE to i1 node");
-
-  if (Op.getOperand(0).getOpcode() != ISD::SRL)
-    return SDValue();
-
-  SDValue ShiftRight = Op.getOperand(0);
-  return getBitTestCondition(ShiftRight.getOperand(0), ShiftRight.getOperand(1),
-                             CC, dl, DAG);
-}
-
-/// Result of 'and' or 'trunc to i1' is compared against zero.
-/// Change to a BT node if possible.
-SDValue X86TargetLowering::LowerToBT(SDValue Op, ISD::CondCode CC,
-                                     const SDLoc &dl, SelectionDAG &DAG) const {
-  if (Op.getOpcode() == ISD::AND)
-    return LowerAndToBT(Op, CC, dl, DAG);
-  if (Op.getOpcode() == ISD::TRUNCATE && Op.getValueType() == MVT::i1)
-    return LowerTruncateToBT(Op, CC, dl, DAG);
-  return SDValue();
-}
-
 /// Turns an ISD::CondCode into a value suitable for SSE floating-point mask
 /// CMPs.
 static int translateX86FSETCC(ISD::CondCode SetCCOpcode, SDValue &Op0,
@@ -17554,14 +17529,10 @@ SDValue X86TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) const {
   // Lower (X & (1 << N)) == 0 to BT(X, N).
   // Lower ((X >>u N) & 1) != 0 to BT(X, N).
   // Lower ((X >>s N) & 1) != 0 to BT(X, N).
-  // Lower (trunc (X >> N) to i1) to BT(X, N).
-  if (Op0.hasOneUse() && isNullConstant(Op1) &&
+  if (Op0.getOpcode() == ISD::AND && Op0.hasOneUse() && isNullConstant(Op1) &&
       (CC == ISD::SETEQ || CC == ISD::SETNE)) {
-    if (SDValue NewSetCC = LowerToBT(Op0, CC, dl, DAG)) {
-      if (VT == MVT::i1)
-        return DAG.getNode(ISD::TRUNCATE, dl, MVT::i1, NewSetCC);
+    if (SDValue NewSetCC = LowerAndToBT(Op0, CC, dl, DAG))
       return NewSetCC;
-    }
   }
 
   // Look for X == 0, X == 1, X != 0, or X != 1.  We can simplify some forms of
@@ -17935,7 +17906,7 @@ SDValue X86TargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const {
     // We know the result of AND is compared against zero. Try to match
     // it to BT.
     if (Cond.getOpcode() == ISD::AND && Cond.hasOneUse()) {
-      if (SDValue NewSetCC = LowerToBT(Cond, ISD::SETNE, DL, DAG)) {
+      if (SDValue NewSetCC = LowerAndToBT(Cond, ISD::SETNE, DL, DAG)) {
         CC = NewSetCC.getOperand(0);
         Cond = NewSetCC.getOperand(1);
         AddTest = false;
@@ -18790,9 +18761,10 @@ SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) const {
     if (isTruncWithZeroHighBitsInput(Cond, DAG))
         Cond = Cond.getOperand(0);
 
-    // We know the result is compared against zero. Try to match it to BT.
-    if (Cond.hasOneUse()) {
-      if (SDValue NewSetCC = LowerToBT(Cond, ISD::SETNE, dl, DAG)) {
+    // We know the result of AND is compared against zero. Try to match
+    // it to BT.
+    if (Cond.getOpcode() == ISD::AND && Cond.hasOneUse()) {
+      if (SDValue NewSetCC = LowerAndToBT(Cond, ISD::SETNE, dl, DAG)) {
         CC = NewSetCC.getOperand(0);
         Cond = NewSetCC.getOperand(1);
         addTest = false;

llvm/lib/Target/X86/X86ISelLowering.h

@@ -1203,8 +1203,6 @@ namespace llvm {
     SDValue lowerUINT_TO_FP_vec(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerTRUNCATE(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFP_TO_INT(SDValue Op, SelectionDAG &DAG) const;
-    SDValue LowerToBT(SDValue And, ISD::CondCode CC, const SDLoc &dl,
-                      SelectionDAG &DAG) const;
     SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSETCCCARRY(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSELECT(SDValue Op, SelectionDAG &DAG) const;