2 files changed, 19 insertions, 4 deletions
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 21ad062eda8..bf0ba09e23a 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -925,7 +925,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const {
       .addReg(StackPtr)
       .setMIFlag(MachineInstr::FrameSetup);
 
-    MFI->setBasePtrStackAdjustment(NumBytes);
+    X86FI->setBasePtrStackAdjustment(NumBytes);
   }
 
   if (( (!HasFP && NumBytes) || PushedRegs) && needsFrameMoves) {
@@ -1051,7 +1051,7 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
             StackPtr).addReg(BasePtr);
 
     // When restoring from the BP we must use a cached SP adjustment.
-    NumBytes = MFI->getBasePtrStackAdjustment();
+    NumBytes = X86FI->getBasePtrStackAdjustment();
   }
 
   // If dynamic alloca is used, then reset esp to point to the last callee-saved
diff --git a/llvm/lib/Target/X86/X86MachineFunctionInfo.h b/llvm/lib/Target/X86/X86MachineFunctionInfo.h
index 2bc308d86c5..cdf907b8c04 100644
--- a/llvm/lib/Target/X86/X86MachineFunctionInfo.h
+++ b/llvm/lib/Target/X86/X86MachineFunctionInfo.h
@@ -69,6 +69,10 @@ class X86MachineFunctionInfo : public MachineFunctionInfo {
   /// NumLocalDynamics - Number of local-dynamic TLS accesses.
   unsigned NumLocalDynamics;
 
+  /// After the stack pointer has been restore from the base pointer we
+  /// use a cached adjusment.
+  int64_t BPAdj;
+
 public:
   X86MachineFunctionInfo() : ForceFramePointer(false),
                              CalleeSavedFrameSize(0),
@@ -97,8 +101,9 @@ public:
       VarArgsGPOffset(0),
       VarArgsFPOffset(0),
       ArgumentStackSize(0),
-      NumLocalDynamics(0) {}
-  
+      NumLocalDynamics(0),
+      BPAdj(0) {}
+
   bool getForceFramePointer() const { return ForceFramePointer;} 
   void setForceFramePointer(bool forceFP) { ForceFramePointer = forceFP; }
 
@@ -137,6 +142,16 @@ public:
 
   unsigned getNumLocalDynamicTLSAccesses() const { return NumLocalDynamics; }
   void incNumLocalDynamicTLSAccesses() { ++NumLocalDynamics; }
+
+  /// setBasePtrStackAdjustment - If we're restoring the stack pointer from the
+  /// base pointer, due to dynamic stack realignment + VLAs, we cache the
+  /// number of bytes initially allocated for the stack frame.  In obscure
+  /// cases (e.g., tail calls with byval argument and no stack protector), the
+  /// stack gets adjusted outside of the prolog, but these shouldn't be 
+  /// considered when restoring from the base pointer.  Currently, this is only
+  /// needed for x86.
+  void setBasePtrStackAdjustment(int64_t adj) { BPAdj = adj; }
+  int64_t getBasePtrStackAdjustment() const { return BPAdj; }
 };
 
 } // End llvm namespace