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

llvm-svn: 150008
diff --git a/llvm/lib/Target/X86/X86.td b/llvm/lib/Target/X86/X86.td
index d5db45b..7f2ece7 100644
--- a/llvm/lib/Target/X86/X86.td
+++ b/llvm/lib/Target/X86/X86.td
@@ -115,6 +115,8 @@
                                       "Support BMI instructions">;
 def FeatureBMI2    : SubtargetFeature<"bmi2", "HasBMI2", "true",
                                       "Support BMI2 instructions">;
+def FeatureLeaForSP : SubtargetFeature<"lea-sp", "UseLeaForSP", "true",
+                                     "Use LEA for adjusting the stack pointer">;
 
 //===----------------------------------------------------------------------===//
 // X86 processors supported.
@@ -155,7 +157,7 @@
 def : Proc<"penryn",          [FeatureSSE41, FeatureCMPXCHG16B,
                                FeatureSlowBTMem]>;
 def : AtomProc<"atom",        [ProcIntelAtom, FeatureSSE3, FeatureCMPXCHG16B,
-                               FeatureMOVBE, FeatureSlowBTMem]>;
+                               FeatureMOVBE, FeatureSlowBTMem, FeatureLeaForSP]>;
 // "Arrandale" along with corei3 and corei5
 def : Proc<"corei7",          [FeatureSSE42, FeatureCMPXCHG16B,
                                FeatureSlowBTMem, FeatureFastUAMem,