Merging r195355:

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r195355 | dsanders | 2013-11-21 13:24:49 +0000 (Thu, 21 Nov 2013) | 20 lines

Add support for legalizing SETNE/SETEQ by inverting the condition code and the result of the comparison.

Summary:
LegalizeSetCCCondCode can now legalize SETEQ and SETNE by returning the inverse
condition and requesting that the caller invert the result of the condition.

The caller of LegalizeSetCCCondCode must handle the inverted CC, and they do
so as follows:
  SETCC, BR_CC:
    Invert the result of the SETCC with SelectionDAG::getNOT()
  SELECT_CC:
    Swap the true/false operands.

This is necessary for MSA which lacks an integer SETNE instruction.

Reviewers: resistor

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2229
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195363 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 54 insertions, 14 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index f50e5e7..9061ae9 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -96,7 +96,7 @@ private:
                                      ArrayRef<int> Mask) const;
 
   bool LegalizeSetCCCondCode(EVT VT, SDValue &LHS, SDValue &RHS, SDValue &CC,
-                             SDLoc dl);
+                             bool &NeedInvert, SDLoc dl);
 
   SDValue ExpandLibCall(RTLIB::Libcall LC, SDNode *Node, bool isSigned);
   SDValue ExpandLibCall(RTLIB::Libcall LC, EVT RetVT, const SDValue *Ops,
@@ -1597,18 +1597,30 @@ void SelectionDAGLegalize::ExpandDYNAMIC_STACKALLOC(SDNode* Node,
 
 /// LegalizeSetCCCondCode - Legalize a SETCC with given LHS and RHS and
 /// condition code CC on the current target.
+///
 /// If the SETCC has been legalized using AND / OR, then the legalized node
-/// will be stored in LHS.  RHS and CC will be set to SDValue().
+/// will be stored in LHS. RHS and CC will be set to SDValue(). NeedInvert
+/// will be set to false.
+///
 /// If the SETCC has been legalized by using getSetCCSwappedOperands(),
-/// then the values of LHS and RHS will be swapped and CC will be set to the
-/// new condition.
+/// then the values of LHS and RHS will be swapped, CC will be set to the
+/// new condition, and NeedInvert will be set to false.
+///
+/// If the SETCC has been legalized using the inverse condcode, then LHS and
+/// RHS will be unchanged, CC will set to the inverted condcode, and NeedInvert
+/// will be set to true. The caller must invert the result of the SETCC with
+/// SelectionDAG::getNOT() or take equivalent action to swap the effect of a
+/// true/false result.
+///
 /// \returns true if the SetCC has been legalized, false if it hasn't.
 bool SelectionDAGLegalize::LegalizeSetCCCondCode(EVT VT,
                                                  SDValue &LHS, SDValue &RHS,
                                                  SDValue &CC,
+                                                 bool &NeedInvert,
                                                  SDLoc dl) {
   MVT OpVT = LHS.getSimpleValueType();
   ISD::CondCode CCCode = cast<CondCodeSDNode>(CC)->get();
+  NeedInvert = false;
   switch (TLI.getCondCodeAction(CCCode, OpVT)) {
   default: llvm_unreachable("Unknown condition code action!");
   case TargetLowering::Legal:
@@ -1661,11 +1673,21 @@ bool SelectionDAGLegalize::LegalizeSetCCCondCode(EVT VT,
     case ISD::SETGT:
     case ISD::SETGE:
     case ISD::SETLT:
-    case ISD::SETNE:
-    case ISD::SETEQ:
       // We only support using the inverted operation, which is computed above
       // and not a different manner of supporting expanding these cases.
       llvm_unreachable("Don't know how to expand this condition!");
+    case ISD::SETNE:
+    case ISD::SETEQ:
+      // Try inverting the result of the inverse condition.
+      InvCC = CCCode == ISD::SETEQ ? ISD::SETNE : ISD::SETEQ;
+      if (TLI.isCondCodeLegal(InvCC, OpVT)) {
+        CC = DAG.getCondCode(InvCC);
+        NeedInvert = true;
+        return true;
+      }
+      // If inverting the condition didn't work then we have no means to expand
+      // the condition.
+      llvm_unreachable("Don't know how to expand this condition!");
     }
 
     SDValue SetCC1, SetCC2;
@@ -2783,6 +2805,7 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
   SmallVector<SDValue, 8> Results;
   SDLoc dl(Node);
   SDValue Tmp1, Tmp2, Tmp3, Tmp4;
+  bool NeedInvert;
   switch (Node->getOpcode()) {
   case ISD::CTPOP:
   case ISD::CTLZ:
@@ -3673,15 +3696,20 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     Tmp2 = Node->getOperand(1);
     Tmp3 = Node->getOperand(2);
     bool Legalized = LegalizeSetCCCondCode(Node->getValueType(0), Tmp1, Tmp2,
-                                           Tmp3, dl);
+                                           Tmp3, NeedInvert, dl);
 
     if (Legalized) {
-      // If we exapanded the SETCC by swapping LHS and RHS, create a new SETCC
-      // node.
+      // If we expanded the SETCC by swapping LHS and RHS, or by inverting the
+      // condition code, create a new SETCC node.
       if (Tmp3.getNode())
         Tmp1 = DAG.getNode(ISD::SETCC, dl, Node->getValueType(0),
                            Tmp1, Tmp2, Tmp3);
 
+      // If we expanded the SETCC by inverting the condition code, then wrap
+      // the existing SETCC in a NOT to restore the intended condition.
+      if (NeedInvert)
+        Tmp1 = DAG.getNOT(dl, Tmp1, Tmp1->getValueType(0));
+
       Results.push_back(Tmp1);
       break;
     }
@@ -3736,11 +3764,18 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
 
     if (!Legalized) {
       Legalized = LegalizeSetCCCondCode(
-          getSetCCResultType(Tmp1.getValueType()), Tmp1, Tmp2, CC, dl);
+          getSetCCResultType(Tmp1.getValueType()), Tmp1, Tmp2, CC, NeedInvert,
+          dl);
 
       assert(Legalized && "Can't legalize SELECT_CC with legal condition!");
-      // If we exapanded the SETCC by swapping LHS and RHS, create a new
-      // SELECT_CC node.
+
+      // If we expanded the SETCC by inverting the condition code, then swap
+      // the True/False operands to match.
+      if (NeedInvert)
+        std::swap(Tmp3, Tmp4);
+
+      // If we expanded the SETCC by swapping LHS and RHS, or by inverting the
+      // condition code, create a new SELECT_CC node.
       if (CC.getNode()) {
         Tmp1 = DAG.getNode(ISD::SELECT_CC, dl, Node->getValueType(0),
                            Tmp1, Tmp2, Tmp3, Tmp4, CC);
@@ -3761,11 +3796,16 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
     Tmp4 = Node->getOperand(1);              // CC
 
     bool Legalized = LegalizeSetCCCondCode(getSetCCResultType(
-        Tmp2.getValueType()), Tmp2, Tmp3, Tmp4, dl);
+        Tmp2.getValueType()), Tmp2, Tmp3, Tmp4, NeedInvert, dl);
     (void)Legalized;
     assert(Legalized && "Can't legalize BR_CC with legal condition!");
 
-    // If we exapanded the SETCC by swapping LHS and RHS, create a new BR_CC
+    // If we expanded the SETCC by inverting the condition code, then wrap
+    // the existing SETCC in a NOT to restore the intended condition.
+    if (NeedInvert)
+      Tmp4 = DAG.getNOT(dl, Tmp4, Tmp4->getValueType(0));
+
+    // If we expanded the SETCC by swapping LHS and RHS, create a new BR_CC
     // node.
     if (Tmp4.getNode()) {
       Tmp1 = DAG.getNode(ISD::BR_CC, dl, Node->getValueType(0), Tmp1,