From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 21 Feb 2007 21:18:14 +0000 (+0000)
Subject: ELF / PIC requires GOT be in the EBX register during calls via PLT GOT pointer.
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=f46847172afea92d73829147a6d9d18cde45ffd7

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 49f5cde9bcc..839eb8a8ab2 100644
--- 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);
   }
 
+  // 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,
@@ -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()));
+
+  // 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);
@@ -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());
 
+  // 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,
@@ -1809,6 +1818,11 @@ SDOperand X86TargetLowering::LowerFastCCCallTo(SDOperand Op, SelectionDAG &DAG,
     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);