ELF / PIC requires GOT be in the EBX register during calls via PLT GOT pointer.

Add implicit uses of EBX to calls to ensure liveintervalanalysis does not treat
the GOT in EBX move as dead upon definition.
This should fix PR1207.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34470 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 49f5cde9bcc1a5468484e2fc293ab66d176a8ac9..839eb8a8ab2a578ca375d498984765938883cb34 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -794,6 +794,8 @@ SDOperand X86TargetLowering::LowerCCCCallTo(SDOperand Op, SelectionDAG &DAG,
     InFlag = Chain.getValue(1);
   }
 
     InFlag = Chain.getValue(1);
   }
 

+  // ELF / PIC requires GOT in the EBX register before function calls via PLT
+  // GOT pointer.

   if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
       Subtarget->isPICStyleGOT()) {
     Chain = DAG.getCopyToReg(Chain, X86::EBX,
   if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
       Subtarget->isPICStyleGOT()) {
     Chain = DAG.getCopyToReg(Chain, X86::EBX,


@@ -825,6 +827,11 @@ SDOperand X86TargetLowering::LowerCCCCallTo(SDOperand Op, SelectionDAG &DAG,
   for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
     Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                   RegsToPass[i].second.getValueType()));
   for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
     Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                   RegsToPass[i].second.getValueType()));

+
+  // Add an implicit use GOT pointer in EBX.
+  if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
+      Subtarget->isPICStyleGOT())
+    Ops.push_back(DAG.getRegister(X86::EBX, getPointerTy()));

   
   if (InFlag.Val)
     Ops.push_back(InFlag);
   
   if (InFlag.Val)
     Ops.push_back(InFlag);


@@ -1788,6 +1795,8 @@ SDOperand X86TargetLowering::LowerFastCCCallTo(SDOperand Op, SelectionDAG &DAG,
   } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee))
     Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
 
   } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee))
     Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
 

+  // ELF / PIC requires GOT in the EBX register before function calls via PLT
+  // GOT pointer.

   if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
       Subtarget->isPICStyleGOT()) {
     Chain = DAG.getCopyToReg(Chain, X86::EBX,
   if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
       Subtarget->isPICStyleGOT()) {
     Chain = DAG.getCopyToReg(Chain, X86::EBX,


@@ -1809,6 +1818,11 @@ SDOperand X86TargetLowering::LowerFastCCCallTo(SDOperand Op, SelectionDAG &DAG,
     Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                   RegsToPass[i].second.getValueType()));
 
     Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                   RegsToPass[i].second.getValueType()));
 

+  // Add an implicit use GOT pointer in EBX.
+  if (getTargetMachine().getRelocationModel() == Reloc::PIC_ &&
+      Subtarget->isPICStyleGOT())
+    Ops.push_back(DAG.getRegister(X86::EBX, getPointerTy()));
+

   if (InFlag.Val)
     Ops.push_back(InFlag);
 
   if (InFlag.Val)
     Ops.push_back(InFlag);