Use LEA to adjust stack ptr for Atom. Patch by Andy Zhang.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150008 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86Subtarget.h

@@ -132,6 +132,10 @@ protected:
   /// this is true for most x86-64 chips, but not the first AMD chips.
   bool HasCmpxchg16b;
 
+  /// UseLeaForSP - True if the LEA instruction should be used for adjusting
+  /// the stack pointer. This is an optimization for Intel Atom processors.
+  bool UseLeaForSP;
+
   /// PostRAScheduler - True if using post-register-allocation scheduler.
   bool PostRAScheduler;
 
@@ -214,6 +218,7 @@ public:
   bool isUnalignedMemAccessFast() const { return IsUAMemFast; }
   bool hasVectorUAMem() const { return HasVectorUAMem; }
   bool hasCmpxchg16b() const { return HasCmpxchg16b; }
+  bool useLeaForSP() const { return UseLeaForSP; }
 
   bool isAtom() const { return X86ProcFamily == IntelAtom; }