1 files changed, 30 insertions, 4 deletions
diff --git a/include/llvm/CodeGen/MachineFrameInfo.h b/include/llvm/CodeGen/MachineFrameInfo.h
index 667736021f927..40f3b4944cc1e 100644
--- a/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/include/llvm/CodeGen/MachineFrameInfo.h
@@ -246,6 +246,21 @@ class MachineFrameInfo {
   /// True if this is a varargs function that contains a musttail call.
   bool HasMustTailInVarArgFunc;
 
+  /// True if this function contains a tail call. If so immutable objects like
+  /// function arguments are no longer so. A tail call *can* override fixed
+  /// stack objects like arguments so we can't treat them as immutable.
+  bool HasTailCall;
+
+  /// Not null, if shrink-wrapping found a better place for the prologue.
+  MachineBasicBlock *Save;
+  /// Not null, if shrink-wrapping found a better place for the epilogue.
+  MachineBasicBlock *Restore;
+
+  /// Check if it exists a path from \p MBB leading to the basic
+  /// block with a SavePoint (a.k.a. prologue).
+  bool isBeforeSavePoint(const MachineFunction &MF,
+                         const MachineBasicBlock &MBB) const;
+
 public:
   explicit MachineFrameInfo(unsigned StackAlign, bool isStackRealign,
                             bool RealignOpt)
@@ -269,6 +284,9 @@ public:
     HasInlineAsmWithSPAdjust = false;
     HasVAStart = false;
     HasMustTailInVarArgFunc = false;
+    Save = nullptr;
+    Restore = nullptr;
+    HasTailCall = false;
   }
 
   /// hasStackObjects - Return true if there are any stack objects in this
@@ -496,6 +514,10 @@ public:
   bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
   void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
 
+  /// Returns true if the function contains a tail call.
+  bool hasTailCall() const { return HasTailCall; }
+  void setHasTailCall() { HasTailCall = true; }
+
   /// getMaxCallFrameSize - Return the maximum size of a call frame that must be
   /// allocated for an outgoing function call.  This is only available if
   /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
@@ -516,10 +538,6 @@ public:
   /// on the stack.  Returns an index with a negative value.
   int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset);
 
-  /// Allocates memory at a fixed, target-specific offset from the frame
-  /// pointer. Marks the function as having its frame address taken.
-  int CreateFrameAllocation(uint64_t Size);
-
   /// isFixedObjectIndex - Returns true if the specified index corresponds to a
   /// fixed stack object.
   bool isFixedObjectIndex(int ObjectIdx) const {
@@ -537,6 +555,9 @@ public:
   /// isImmutableObjectIndex - Returns true if the specified index corresponds
   /// to an immutable object.
   bool isImmutableObjectIndex(int ObjectIdx) const {
+    // Tail calling functions can clobber their function arguments.
+    if (HasTailCall)
+      return false;
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isImmutable;
@@ -601,6 +622,11 @@ public:
 
   void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
 
+  MachineBasicBlock *getSavePoint() const { return Save; }
+  void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
+  MachineBasicBlock *getRestorePoint() const { return Restore; }
+  void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
+
   /// getPristineRegs - Return a set of physical registers that are pristine on
   /// entry to the MBB.
   ///