Change the calling convention used when tail call optimization is enabled from CC_X86_32_TailCall to CC_X86_32_FastCC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56436 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 3401a2c..78121bd 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -890,7 +890,7 @@
     SDValue TargetAddress = TailCall.getOperand(1);
     SDValue StackAdjustment = TailCall.getOperand(2);
     assert(((TargetAddress.getOpcode() == ISD::Register &&
-               (cast<RegisterSDNode>(TargetAddress)->getReg() == X86::ECX ||
+               (cast<RegisterSDNode>(TargetAddress)->getReg() == X86::EAX ||
                 cast<RegisterSDNode>(TargetAddress)->getReg() == X86::R9)) ||
               TargetAddress.getOpcode() == ISD::TargetExternalSymbol ||
               TargetAddress.getOpcode() == ISD::TargetGlobalAddress) && 
@@ -1098,8 +1098,6 @@
 
   if (CC == CallingConv::X86_FastCall)
     return CC_X86_32_FastCall;
-  else if (CC == CallingConv::Fast && PerformTailCallOpt)
-    return CC_X86_32_TailCall;
   else if (CC == CallingConv::Fast)
     return CC_X86_32_FastCC;
   else
@@ -1700,7 +1698,7 @@
   } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
     Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
   } else if (IsTailCall) {
-    unsigned Opc = Is64Bit ? X86::R9 : X86::ECX;
+    unsigned Opc = Is64Bit ? X86::R9 : X86::EAX;
 
     Chain = DAG.getCopyToReg(Chain, 
                              DAG.getRegister(Opc, getPointerTy()),