Re-apply r127953 with fixes: eliminate empty return block if it has no predecessors; update dominator tree if cfg is modified.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127981 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 576c879..58acf4f 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -45,6 +45,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/VectorExtras.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
@@ -1595,6 +1596,18 @@
return (CC == CallingConv::Fast || CC == CallingConv::GHC);
}
+bool X86TargetLowering::mayBeEmittedAsTailCall(CallInst *CI) const {
+ if (!CI->isTailCall())
+ return false;
+
+ CallSite CS(CI);
+ CallingConv::ID CalleeCC = CS.getCallingConv();
+ if (!IsTailCallConvention(CalleeCC) && CalleeCC != CallingConv::C)
+ return false;
+
+ return true;
+}
+
/// FuncIsMadeTailCallSafe - Return true if the function is being made into
/// a tailcall target by changing its ABI.
static bool FuncIsMadeTailCallSafe(CallingConv::ID CC) {