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.
llvm-svn: 34470
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 49f5cde..839eb8a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -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);