Enables vararg functions that pass all arguments via registers to be optimized into tail-calls when possible.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131560 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index ff4a283..9b985f9 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2525,16 +2525,29 @@
if (RegInfo->needsStackRealignment(MF))
return false;
- // Do not sibcall optimize vararg calls unless the call site is not passing
- // any arguments.
- if (isVarArg && !Outs.empty())
- return false;
-
// Also avoid sibcall optimization if either caller or callee uses struct
// return semantics.
if (isCalleeStructRet || isCallerStructRet)
return false;
+ // Do not sibcall optimize vararg calls unless all arguments are passed via
+ // registers
+ if (isVarArg && !Outs.empty()) {
+ SmallVector<CCValAssign, 16> ArgLocs;
+ CCState CCInfo(CalleeCC, isVarArg, getTargetMachine(),
+ ArgLocs, *DAG.getContext());
+
+ // Allocate shadow area for Win64
+ if (Subtarget->isTargetWin64()) {
+ CCInfo.AllocateStack(32, 8);
+ }
+
+ CCInfo.AnalyzeCallOperands(Outs, CC_X86);
+ for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i)
+ if (!ArgLocs[i].isRegLoc())
+ return false;
+ }
+
// If the call result is in ST0 / ST1, it needs to be popped off the x87 stack.
// Therefore if it's not used by the call it is not safe to optimize this into
// a sibcall.