Add support for ELF PLT references for ARM MC asm printing. Adding a

new VariantKind to the MCSymbolExpr seems like overkill, but I'm not sure
there's a more straightforward way to get the printing difference captured.
(i.e., x86 uses @PLT, ARM uses (PLT)).

llvm-svn: 114613

4 files changed, 45 insertions, 15 deletions

diff --git a/llvm/lib/Target/ARM/ARMBaseInfo.h b/llvm/lib/Target/ARM/ARMBaseInfo.h
index a460a5c05ca..2da7be25a13 100644
--- a/llvm/lib/Target/ARM/ARMBaseInfo.h
+++ b/llvm/lib/Target/ARM/ARMBaseInfo.h
@@ -181,7 +181,11 @@ namespace ARMII {
 
     /// MO_HI16 - On a symbol operand, this represents a relocation containing
     /// higher 16 bit of the address. Used only via movt instruction.
-    MO_HI16
+    MO_HI16,
+
+    /// MO_PLT - On a symbol operand, this represents an ELF PLT reference on a
+    /// call operand.
+    MO_PLT
   };
 } // end namespace ARMII
 
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index dc68d3980f6..ae1fead462d 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1195,8 +1195,14 @@ ARMTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
       SDValue PICLabel = DAG.getConstant(ARMPCLabelIndex, MVT::i32);
       Callee = DAG.getNode(ARMISD::PIC_ADD, dl,
                            getPointerTy(), Callee, PICLabel);
-    } else
-      Callee = DAG.getTargetGlobalAddress(GV, dl, getPointerTy());
+    } else {
+      // On ELF targets for PIC code, direct calls should go through the PLT
+      unsigned OpFlags = 0;
+      if (Subtarget->isTargetELF() &&
+                  getTargetMachine().getRelocationModel() == Reloc::PIC_)
+        OpFlags = ARMII::MO_PLT;
+      Callee = DAG.getTargetGlobalAddress(GV, dl, getPointerTy(), 0, OpFlags);
+    }
   } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
     isDirect = true;
     bool isStub = Subtarget->isTargetDarwin() &&
@@ -1217,8 +1223,14 @@ ARMTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
       SDValue PICLabel = DAG.getConstant(ARMPCLabelIndex, MVT::i32);
       Callee = DAG.getNode(ARMISD::PIC_ADD, dl,
                            getPointerTy(), Callee, PICLabel);
-    } else
-      Callee = DAG.getTargetExternalSymbol(Sym, getPointerTy());
+    } else {
+      unsigned OpFlags = 0;
+      // On ELF targets for PIC code, direct calls should go through the PLT
+      if (Subtarget->isTargetELF() &&
+                  getTargetMachine().getRelocationModel() == Reloc::PIC_)
+        OpFlags = ARMII::MO_PLT;
+      Callee = DAG.getTargetExternalSymbol(Sym, getPointerTy(), OpFlags);
+    }
   }
 
   // FIXME: handle tail calls differently.
diff --git a/llvm/lib/Target/ARM/ARMMCInstLower.cpp b/llvm/lib/Target/ARM/ARMMCInstLower.cpp
index ecd289c7962..e2155f1a02a 100644
--- a/llvm/lib/Target/ARM/ARMMCInstLower.cpp
+++ b/llvm/lib/Target/ARM/ARMMCInstLower.cpp
@@ -33,7 +33,6 @@ MCSymbol *ARMMCInstLower::GetGlobalAddressSymbol(const GlobalValue *GV) const {
 const MCSymbolRefExpr *ARMMCInstLower::
 GetSymbolRef(const MachineOperand &MO) const {
   assert(MO.isGlobal() && "Isn't a global address reference?");
-  // FIXME: HANDLE PLT references how??
 
   const MCSymbolRefExpr *SymRef;
   const MCSymbol *Symbol = GetGlobalAddressSymbol(MO.getGlobal());
@@ -49,22 +48,36 @@ GetSymbolRef(const MachineOperand &MO) const {
   case ARMII::MO_HI16:
     SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_HI16, Ctx);
     break;
+  case ARMII::MO_PLT:
+    SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_PLT, Ctx);
+    break;
   }
 
   return SymRef;
 }
 
-MCSymbol *ARMMCInstLower::
+const MCSymbolRefExpr *ARMMCInstLower::
 GetExternalSymbolSymbol(const MachineOperand &MO) const {
-  // FIXME: HANDLE PLT references how??
-  // FIXME: This probably needs to be merged with the above SymbolRef stuff
-  // to handle :lower16: and :upper16: (?)
+  const MCSymbolRefExpr *SymRef;
+  const MCSymbol *Symbol = Printer.GetExternalSymbolSymbol(MO.getSymbolName());
+
   switch (MO.getTargetFlags()) {
-  default: assert(0 && "Unknown target flag on GV operand");
-  case 0: break;
+  default: assert(0 && "Unknown target flag on external symbol operand");
+  case 0:
+    SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_None, Ctx);
+    break;
+  case ARMII::MO_LO16:
+    SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_LO16, Ctx);
+    break;
+  case ARMII::MO_HI16:
+    SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_HI16, Ctx);
+    break;
+  case ARMII::MO_PLT:
+    SymRef = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_PLT, Ctx);
+    break;
   }
 
-  return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
+  return SymRef;
 }
 
 
@@ -157,7 +170,7 @@ void ARMMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
       MCOp = LowerSymbolRefOperand(MO, GetSymbolRef(MO));
       break;
     case MachineOperand::MO_ExternalSymbol:
-      MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
+      MCOp = LowerSymbolRefOperand(MO, GetExternalSymbolSymbol(MO));
       break;
     case MachineOperand::MO_JumpTableIndex:
       MCOp = LowerSymbolOperand(MO, GetJumpTableSymbol(MO));
diff --git a/llvm/lib/Target/ARM/ARMMCInstLower.h b/llvm/lib/Target/ARM/ARMMCInstLower.h
index 79ed2e9c484..c4d27f88df1 100644
--- a/llvm/lib/Target/ARM/ARMMCInstLower.h
+++ b/llvm/lib/Target/ARM/ARMMCInstLower.h
@@ -43,7 +43,8 @@ public:
   //MCSymbol *GetPICBaseSymbol() const;
   MCSymbol *GetGlobalAddressSymbol(const GlobalValue *GV) const;
   const MCSymbolRefExpr *GetSymbolRef(const MachineOperand &MO) const;
-  MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
+  const MCSymbolRefExpr *GetExternalSymbolSymbol(const MachineOperand &MO)
+    const;
   MCSymbol *GetJumpTableSymbol(const MachineOperand &MO) const;
   MCSymbol *GetConstantPoolIndexSymbol(const MachineOperand &MO) const;
   MCOperand LowerSymbolRefOperand(const MachineOperand &MO,