[llvm-commits] CVS: llvm/lib/Target/X86/X86ISelLowering.cpp

[Evan Cheng]

Changes in directory llvm/lib/Target/X86:

X86ISelLowering.cpp updated: 1.320 -> 1.321
---
Log message:

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: http://llvm.org/PR1207 .

---
Diffs of the changes:  (+14 -0)

 X86ISelLowering.cpp |   14 ++++++++++++++
 1 files changed, 14 insertions(+)


Index: llvm/lib/Target/X86/X86ISelLowering.cpp
diff -u llvm/lib/Target/X86/X86ISelLowering.cpp:1.320 llvm/lib/Target/X86/X86ISelLowering.cpp:1.321
--- llvm/lib/Target/X86/X86ISelLowering.cpp:1.320	Thu Feb  1 02:39:52 2007
+++ llvm/lib/Target/X86/X86ISelLowering.cpp	Wed Feb 21 15:18:14 2007
@@ -794,6 +794,8 @@
     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 @@
   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 @@
   } 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 @@
     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);