Fix Bug 4278: X86-64 with -tailcallopt calling convention
out of sync with regular cc.
The only difference between the tail call cc and the normal
cc was that one parameter register - R9 - was reserved for
calling functions through a function pointer. After time the
tail call cc has gotten out of sync with the regular cc.
We can use R11 which is also caller saved but not used as
parameter register for potential function pointers and
remove the special tail call cc on x86-64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73233 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2f94b67..36e3ab2 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -944,7 +944,7 @@
SDValue StackAdjustment = TailCall.getOperand(2);
assert(((TargetAddress.getOpcode() == ISD::Register &&
(cast<RegisterSDNode>(TargetAddress)->getReg() == X86::EAX ||
- cast<RegisterSDNode>(TargetAddress)->getReg() == X86::R9)) ||
+ cast<RegisterSDNode>(TargetAddress)->getReg() == X86::R11)) ||
TargetAddress.getOpcode() == ISD::TargetExternalSymbol ||
TargetAddress.getOpcode() == ISD::TargetGlobalAddress) &&
"Expecting an global address, external symbol, or register");
@@ -1171,8 +1171,6 @@
if (Subtarget->is64Bit()) {
if (Subtarget->isTargetWin64())
return CC_X86_Win64_C;
- else if (CC == CallingConv::Fast && PerformTailCallOpt)
- return CC_X86_64_TailCall;
else
return CC_X86_64_C;
}
@@ -1799,7 +1797,7 @@
} else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
} else if (IsTailCall) {
- unsigned Opc = Is64Bit ? X86::R9 : X86::EAX;
+ unsigned Opc = Is64Bit ? X86::R11 : X86::EAX;
Chain = DAG.getCopyToReg(Chain, dl,
DAG.getRegister(Opc, getPointerTy()),