Fix divmod libcall lowering. Convert to {S|U}DIVREM first and then expand the node to a libcall. rdar://9280991

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129633 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 96 insertions, 71 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index e42e4cd22e..bf06adbf6b 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -158,7 +158,7 @@ private:
                            RTLIB::Libcall Call_I32,
                            RTLIB::Libcall Call_I64,
                            RTLIB::Libcall Call_I128);
-  SDValue ExpandDivRemLibCall(SDNode *Node, bool isSigned, bool isDIV);
+  void ExpandDivRemLibCall(SDNode *Node, SmallVectorImpl<SDValue> &Results);
 
   SDValue EmitStackConvert(SDValue SrcOp, EVT SlotVT, EVT DestVT, DebugLoc dl);
   SDValue ExpandBUILD_VECTOR(SDNode *Node);
@@ -2121,10 +2121,9 @@ SDValue SelectionDAGLegalize::ExpandIntLibCall(SDNode* Node, bool isSigned,
   return ExpandLibCall(LC, Node, isSigned);
 }
 
-/// ExpandDivRemLibCall - Issue libcalls to __{u}divmod to compute div / rem
-/// pairs.
-SDValue SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node, bool isSigned,
-                                                  bool isDIV) {
+/// isDivRemLibcallAvailable - Return true if divmod libcall is available.
+static bool isDivRemLibcallAvailable(SDNode *Node, bool isSigned,
+                                     const TargetLowering &TLI) {
   RTLIB::Libcall LC;
   switch (Node->getValueType(0).getSimpleVT().SimpleTy) {
   default: assert(0 && "Unexpected request for libcall!");
@@ -2135,17 +2134,18 @@ SDValue SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node, bool isSigned,
   case MVT::i128: LC= isSigned ? RTLIB::SDIVREM_I128:RTLIB::UDIVREM_I128; break;
   }
 
-  if (!TLI.getLibcallName(LC))
-    return SDValue();
+  return TLI.getLibcallName(LC) != 0;
+}
 
-  // Only issue divrem libcall if both quotient and remainder are needed.
+/// UseDivRem - Only issue divrem libcall if both quotient and remainder are
+/// needed.
+static bool UseDivRem(SDNode *Node, bool isSigned, bool isDIV) {
   unsigned OtherOpcode = 0;
-  if (isSigned) {
+  if (isSigned)
     OtherOpcode = isDIV ? ISD::SREM : ISD::SDIV;
-  } else {
+  else
     OtherOpcode = isDIV ? ISD::UREM : ISD::UDIV;
-  }
-  SDNode *OtherNode = 0;
+
   SDValue Op0 = Node->getOperand(0);
   SDValue Op1 = Node->getOperand(1);
   for (SDNode::use_iterator UI = Op0.getNode()->use_begin(),
@@ -2155,32 +2155,28 @@ SDValue SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node, bool isSigned,
       continue;
     if (User->getOpcode() == OtherOpcode &&
         User->getOperand(0) == Op0 &&
-        User->getOperand(1) == Op1) {
-      OtherNode = User;
-      break;
-    }
+        User->getOperand(1) == Op1)
+      return true;
   }
-  if (!OtherNode)
-    return SDValue();
+  return false;
+}
 
-  // If the libcall is already generated, no need to issue it again.
-  DenseMap<SDValue, SDValue>::iterator I
-    = LegalizedNodes.find(SDValue(OtherNode,0));
-  if (I != LegalizedNodes.end()) {
-    OtherNode = I->second.getNode();
-    SDNode *Chain = OtherNode->getOperand(0).getNode();
-    for (SDNode::use_iterator UI = Chain->use_begin(), UE = Chain->use_end();
-         UI != UE; ++UI) {
-      SDNode *User = *UI;
-      if (User == OtherNode)
-        continue;
-      if (isDIV) {
-        assert(User->getOpcode() == ISD::CopyFromReg);
-      } else {
-        assert(User->getOpcode() == ISD::LOAD);
-      }
-      return SDValue(User, 0);
-    }
+/// ExpandDivRemLibCall - Issue libcalls to __{u}divmod to compute div / rem
+/// pairs.
+void
+SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node,
+                                          SmallVectorImpl<SDValue> &Results) {
+  unsigned Opcode = Node->getOpcode();
+  bool isSigned = Opcode == ISD::SDIVREM;
+
+  RTLIB::Libcall LC;
+  switch (Node->getValueType(0).getSimpleVT().SimpleTy) {
+  default: assert(0 && "Unexpected request for libcall!");
+  case MVT::i8:   LC= isSigned ? RTLIB::SDIVREM_I8  : RTLIB::UDIVREM_I8;  break;
+  case MVT::i16:  LC= isSigned ? RTLIB::SDIVREM_I16 : RTLIB::UDIVREM_I16; break;
+  case MVT::i32:  LC= isSigned ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32; break;
+  case MVT::i64:  LC= isSigned ? RTLIB::SDIVREM_I64 : RTLIB::UDIVREM_I64; break;
+  case MVT::i128: LC= isSigned ? RTLIB::SDIVREM_I128:RTLIB::UDIVREM_I128; break;
   }
 
   // The input chain to this libcall is the entry node of the function.
@@ -2228,7 +2224,8 @@ SDValue SelectionDAGLegalize::ExpandDivRemLibCall(SDNode *Node, bool isSigned,
   // Remainder is loaded back from the stack frame.
   SDValue Rem = DAG.getLoad(RetVT, dl, LastCALLSEQ_END, FIPtr,
                             MachinePointerInfo(), false, false, 0);
-  return isDIV ? CallInfo.first : Rem;
+  Results.push_back(CallInfo.first);
+  Results.push_back(Rem);
 }
 
 /// ExpandLegalINT_TO_FP - This function is responsible for legalizing a
@@ -3204,28 +3201,25 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
     unsigned DivRemOpc = isSigned ? ISD::SDIVREM : ISD::UDIVREM;
     Tmp2 = Node->getOperand(0);
     Tmp3 = Node->getOperand(1);
-    if (TLI.isOperationLegalOrCustom(DivRemOpc, VT)) {
+    if (TLI.isOperationLegalOrCustom(DivRemOpc, VT) ||
+        (isDivRemLibcallAvailable(Node, isSigned, TLI) &&
+         UseDivRem(Node, isSigned, false))) {
       Tmp1 = DAG.getNode(DivRemOpc, dl, VTs, Tmp2, Tmp3).getValue(1);
     } else if (TLI.isOperationLegalOrCustom(DivOpc, VT)) {
       // X % Y -> X-X/Y*Y
       Tmp1 = DAG.getNode(DivOpc, dl, VT, Tmp2, Tmp3);
       Tmp1 = DAG.getNode(ISD::MUL, dl, VT, Tmp1, Tmp3);
       Tmp1 = DAG.getNode(ISD::SUB, dl, VT, Tmp2, Tmp1);
-    } else if (isSigned) {
-      Tmp1 = ExpandDivRemLibCall(Node, true, false);
-      if (!Tmp1.getNode())
-        Tmp1 = ExpandIntLibCall(Node, true,
-                                RTLIB::SREM_I8,
-                                RTLIB::SREM_I16, RTLIB::SREM_I32,
-                                RTLIB::SREM_I64, RTLIB::SREM_I128);
-    } else {
-      Tmp1 = ExpandDivRemLibCall(Node, false, false);
-      if (!Tmp1.getNode())
-        Tmp1 = ExpandIntLibCall(Node, false,
-                                RTLIB::UREM_I8,
-                                RTLIB::UREM_I16, RTLIB::UREM_I32,
-                                RTLIB::UREM_I64, RTLIB::UREM_I128);
-    }
+    } else if (isSigned)
+      Tmp1 = ExpandIntLibCall(Node, true,
+                              RTLIB::SREM_I8,
+                              RTLIB::SREM_I16, RTLIB::SREM_I32,
+                              RTLIB::SREM_I64, RTLIB::SREM_I128);
+    else
+      Tmp1 = ExpandIntLibCall(Node, false,
+                              RTLIB::UREM_I8,
+                              RTLIB::UREM_I16, RTLIB::UREM_I32,
+                              RTLIB::UREM_I64, RTLIB::UREM_I128);
     Results.push_back(Tmp1);
     break;
   }
@@ -3235,26 +3229,21 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
     unsigned DivRemOpc = isSigned ? ISD::SDIVREM : ISD::UDIVREM;
     EVT VT = Node->getValueType(0);
     SDVTList VTs = DAG.getVTList(VT, VT);
-    if (TLI.isOperationLegalOrCustom(DivRemOpc, VT))
+    if (TLI.isOperationLegalOrCustom(DivRemOpc, VT) ||
+        (isDivRemLibcallAvailable(Node, isSigned, TLI) &&
+         UseDivRem(Node, isSigned, true)))
       Tmp1 = DAG.getNode(DivRemOpc, dl, VTs, Node->getOperand(0),
                          Node->getOperand(1));
-    else if (isSigned) {
-      Tmp1 = ExpandDivRemLibCall(Node, true, true);
-      if (!Tmp1.getNode()) {
-        Tmp1 = ExpandIntLibCall(Node, true,
-                                RTLIB::SDIV_I8,
-                                RTLIB::SDIV_I16, RTLIB::SDIV_I32,
-                                RTLIB::SDIV_I64, RTLIB::SDIV_I128);
-      }
-    } else {
-      Tmp1 = ExpandDivRemLibCall(Node, false, true);
-      if (!Tmp1.getNode()) {
-        Tmp1 = ExpandIntLibCall(Node, false,
-                                RTLIB::UDIV_I8,
-                                RTLIB::UDIV_I16, RTLIB::UDIV_I32,
-                                RTLIB::UDIV_I64, RTLIB::UDIV_I128);
-      }
-    }
+    else if (isSigned)
+      Tmp1 = ExpandIntLibCall(Node, true,
+                              RTLIB::SDIV_I8,
+                              RTLIB::SDIV_I16, RTLIB::SDIV_I32,
+                              RTLIB::SDIV_I64, RTLIB::SDIV_I128);
+    else
+      Tmp1 = ExpandIntLibCall(Node, false,
+                              RTLIB::UDIV_I8,
+                              RTLIB::UDIV_I16, RTLIB::UDIV_I32,
+                              RTLIB::UDIV_I64, RTLIB::UDIV_I128);
     Results.push_back(Tmp1);
     break;
   }
@@ -3271,6 +3260,11 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
     Results.push_back(Tmp1.getValue(1));
     break;
   }
+  case ISD::SDIVREM:
+  case ISD::UDIVREM:
+    // Expand into divrem libcall
+    ExpandDivRemLibCall(Node, Results);
+    break;
   case ISD::MUL: {
     EVT VT = Node->getValueType(0);
     SDVTList VTs = DAG.getVTList(VT, VT);
diff --git a/test/CodeGen/ARM/divmod.ll b/test/CodeGen/ARM/divmod.ll
index 04b8fbf0f0..9c90a8296b 100644
--- a/test/CodeGen/ARM/divmod.ll
+++ b/test/CodeGen/ARM/divmod.ll
@@ -25,3 +25,34 @@ entry:
   store i32 %rem, i32* %arrayidx6, align 4
   ret void
 }
+
+; rdar://9280991
+@flags = external unnamed_addr global i32
+@tabsize = external unnamed_addr global i32
+
+define void @do_indent(i32 %cols) nounwind {
+entry:
+; CHECK: do_indent:
+  %0 = load i32* @flags, align 4
+  %1 = and i32 %0, 67108864
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb
+
+bb:
+; CHECK: bl ___divmodsi4
+  %3 = load i32* @tabsize, align 4
+  %4 = srem i32 %cols, %3
+  %5 = sdiv i32 %cols, %3
+  %6 = tail call i32 @llvm.objectsize.i32(i8* null, i1 false)
+  %7 = tail call i8* @__memset_chk(i8* null, i32 9, i32 %5, i32 %6) nounwind
+  br label %bb1
+
+bb1:
+  %line_indent_len.0 = phi i32 [ %4, %bb ], [ 0, %entry ]
+  %8 = getelementptr inbounds i8* null, i32 %line_indent_len.0
+  store i8 0, i8* %8, align 1
+  ret void
+}
+
+declare i32 @llvm.objectsize.i32(i8*, i1) nounwind readnone
+declare i8* @__memset_chk(i8*, i32, i32, i32) nounwind