Indirect tail call has to go through a call preserved register since it's after callee register pops. X86 isel lowering is using EAX / R11 and it was somehow adding that to function live out. That prevented the real function return register from being added to the function live out list and bad things happen.
This fixes 483.xalancbmk (with tail call opt).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95280 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2b5ff3c..a44afb5 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1196,13 +1196,11 @@
RVLocs, *DAG.getContext());
CCInfo.AnalyzeReturn(Outs, RetCC_X86);
- // If this is the first return lowered for this function, add the regs to the
- // liveout set for the function.
- if (DAG.getMachineFunction().getRegInfo().liveout_empty()) {
- for (unsigned i = 0; i != RVLocs.size(); ++i)
- if (RVLocs[i].isRegLoc())
- DAG.getMachineFunction().getRegInfo().addLiveOut(RVLocs[i].getLocReg());
- }
+ // Add the regs to the liveout set for the function.
+ MachineRegisterInfo &MRI = DAG.getMachineFunction().getRegInfo();
+ for (unsigned i = 0; i != RVLocs.size(); ++i)
+ if (RVLocs[i].isRegLoc() && !MRI.isLiveOut(RVLocs[i].getLocReg()))
+ MRI.addLiveOut(RVLocs[i].getLocReg());
SDValue Flag;
@@ -1255,7 +1253,7 @@
X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
unsigned Reg = FuncInfo->getSRetReturnReg();
if (!Reg) {
- Reg = MF.getRegInfo().createVirtualRegister(getRegClassFor(MVT::i64));
+ Reg = MRI.createVirtualRegister(getRegClassFor(MVT::i64));
FuncInfo->setSRetReturnReg(Reg);
}
SDValue Val = DAG.getCopyFromReg(Chain, dl, Reg, getPointerTy());
@@ -1264,7 +1262,7 @@
Flag = Chain.getValue(1);
// RAX now acts like a return value.
- MF.getRegInfo().addLiveOut(X86::RAX);
+ MRI.addLiveOut(X86::RAX);
}
RetOps[0] = Chain; // Update chain.
@@ -2097,14 +2095,15 @@
}
if (isTailCall && !WasGlobalOrExternal) {
- unsigned Opc = Is64Bit ? X86::R11 : X86::EAX;
-
+ // Force the address into a (call preserved) caller-saved register since
+ // tailcall must happen after callee-saved registers are poped.
+ // FIXME: Give it a special register class that contains caller-saved
+ // register instead?
+ unsigned TCReg = Is64Bit ? X86::R11 : X86::EAX;
Chain = DAG.getCopyToReg(Chain, dl,
- DAG.getRegister(Opc, getPointerTy()),
+ DAG.getRegister(TCReg, getPointerTy()),
Callee,InFlag);
- Callee = DAG.getRegister(Opc, getPointerTy());
- // Add register as live out.
- MF.getRegInfo().addLiveOut(Opc);
+ Callee = DAG.getRegister(TCReg, getPointerTy());
}
// Returns a chain & a flag for retval copy to use.