From: Evan Cheng <evan.cheng@apple.com>
Date: Mon, 15 Mar 2010 18:54:48 +0000 (+0000)
Subject: Avoid sibcall optimization if either caller or callee is using sret semantics.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a375d471378b1674a9d77d180a0b05ea8c90cb4b;p=oota-llvm.git

Avoid sibcall optimization if either caller or callee is using sret semantics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98561 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 9c541dd1b9f..06642a9a77c 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1524,7 +1524,6 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain,
                                         DebugLoc dl,
                                         SelectionDAG &DAG,
                                         SmallVectorImpl<SDValue> &InVals) {
-
   MachineFunction &MF = DAG.getMachineFunction();
   X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
 
@@ -1826,7 +1825,8 @@ X86TargetLowering::LowerCall(SDValue Chain, SDValue Callee,
 
   if (isTailCall) {
     // Check if it's really possible to do a tail call.
-    isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv, isVarArg,
+    isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv,
+                    isVarArg, IsStructRet, MF.getFunction()->hasStructRetAttr(),
                                                    Outs, Ins, DAG);
 
     // Sibcalls are automatically detected tailcalls which do not require
@@ -2324,6 +2324,8 @@ bool
 X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
                                                      CallingConv::ID CalleeCC,
                                                      bool isVarArg,
+                                                     bool isCalleeStructRet,
+                                                     bool isCallerStructRet,
                                     const SmallVectorImpl<ISD::OutputArg> &Outs,
                                     const SmallVectorImpl<ISD::InputArg> &Ins,
                                                      SelectionDAG& DAG) const {
@@ -2343,10 +2345,15 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
   // Look for obvious safe cases to perform tail call optimization that does not
   // requite ABI changes. This is what gcc calls sibcall.
 
-  // Do not tail call optimize vararg calls for now.
+  // Do not sibcall optimize vararg calls for now.
   if (isVarArg)
     return false;
 
+  // Also avoid sibcall optimization if either caller or callee uses struct
+  // return semantics.
+  if (isCalleeStructRet || isCallerStructRet)
+    return false;
+
   // If the callee takes no arguments then go on to check the results of the
   // call.
   if (!Outs.empty()) {
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index 4c07b65d4d3..0f15ebafb0e 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -630,6 +630,8 @@ namespace llvm {
     bool IsEligibleForTailCallOptimization(SDValue Callee,
                                            CallingConv::ID CalleeCC,
                                            bool isVarArg,
+                                           bool isCalleeStructRet,
+                                           bool isCallerStructRet,
                                     const SmallVectorImpl<ISD::OutputArg> &Outs,
                                     const SmallVectorImpl<ISD::InputArg> &Ins,
                                            SelectionDAG& DAG) const;