X86: when we are auto-detecting the subtarget features, make sure we turn on
FeatureFastUAMem for Nehalem, Westmere and Sandy Bridge.

FeatureFastUAMem is already on if we pass in nehalem or westmere as a command
argument.

rdar: 7252306


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161717 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86Subtarget.cpp b/lib/Target/X86/X86Subtarget.cpp
index ae22298..d7e3efc 100644
--- a/lib/Target/X86/X86Subtarget.cpp
+++ b/lib/Target/X86/X86Subtarget.cpp
@@ -246,8 +246,11 @@
     }
 
     // If it's Nehalem, unaligned memory access is fast.
-    // FIXME: Nehalem is family 6. Also include Westmere and later processors?
-    if (Family == 15 && Model == 26) {
+    // Include Westmere and Sandy Bridge as well.
+    // FIXME: add later processors.
+    if ((Family == 6 && Model == 26) ||
+        (Family == 6 && Model == 44) ||
+        (Family == 6 && Model == 42)) {
       IsUAMemFast = true;
       ToggleFeature(X86::FeatureFastUAMem);
     }