Do not sibcall if stack needs to be dynamically aligned.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99620 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index d08dfc4..707b9fe 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2290,6 +2290,7 @@
     return false;
 
   // If -tailcallopt is specified, make fastcc functions tail-callable.
+  const MachineFunction &MF = DAG.getMachineFunction();
   const Function *CallerF = DAG.getMachineFunction().getFunction();
   if (GuaranteedTailCallOpt) {
     if (IsTailCallConvention(CalleeCC) &&
@@ -2301,6 +2302,11 @@
   // Look for obvious safe cases to perform tail call optimization that does not
   // requite ABI changes. This is what gcc calls sibcall.
 
+  // Can't do sibcall if stack needs to be dynamically re-aligned. PEI needs to
+  // emit a special epilogue.
+  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())