[X86] Add missing key feature for core2

clang/test/CodeGen/attr-target-mv.c

 // RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=LINUX
 // RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-windows-pc -emit-llvm %s -o - | FileCheck %s --check-prefix=WINDOWS
 
 int __attribute__((target("sse4.2"))) foo(void) { return 0; }
 int __attribute__((target("arch=sandybridge"))) foo(void);
 int __attribute__((target("arch=ivybridge"))) foo(void) {return 1;}
 int __attribute__((target("arch=goldmont"))) foo(void) {return 3;}
 int __attribute__((target("arch=goldmont-plus"))) foo(void) {return 4;}
 int __attribute__((target("arch=tremont"))) foo(void) {return 5;}
 int __attribute__((target("arch=icelake-client"))) foo(void) {return 6;}
 int __attribute__((target("arch=icelake-server"))) foo(void) {return 7;}
 int __attribute__((target("arch=cooperlake"))) foo(void) {return 8;}
 int __attribute__((target("arch=tigerlake"))) foo(void) {return 9;}
 int __attribute__((target("arch=sapphirerapids"))) foo(void) {return 10;}
 int __attribute__((target("arch=alderlake"))) foo(void) {return 11;}
 int __attribute__((target("arch=rocketlake"))) foo(void) {return 12;}
+int __attribute__((target("arch=core2"))) foo(void) {return 13;}
 int __attribute__((target("default"))) foo(void) { return 2; }
 
 int bar(void) {
   return foo();
 }
 
 inline int __attribute__((target("sse4.2"))) foo_inline(void) { return 0; }
 inline int __attribute__((target("arch=sandybridge"))) foo_inline(void);

 // LINUX: define{{.*}} i32 @foo.arch_tigerlake()
 // LINUX: ret i32 9
 // LINUX: define{{.*}} i32 @foo.arch_sapphirerapids()
 // LINUX: ret i32 10
 // LINUX: define{{.*}} i32 @foo.arch_alderlake()
 // LINUX: ret i32 11
 // LINUX: define{{.*}} i32 @foo.arch_rocketlake()
 // LINUX: ret i32 12
+// LINUX: define{{.*}} i32 @foo.arch_core2()
+// LINUX: ret i32 13
 // LINUX: define{{.*}} i32 @foo()
 // LINUX: ret i32 2
 // LINUX: define{{.*}} i32 @bar()
 // LINUX: call i32 @foo.ifunc()
 
 // WINDOWS: define dso_local i32 @foo.sse4.2()
 // WINDOWS: ret i32 0
 // WINDOWS: define dso_local i32 @foo.arch_ivybridge()

 // WINDOWS: define dso_local i32 @foo.arch_tigerlake()
 // WINDOWS: ret i32 9
 // WINDOWS: define dso_local i32 @foo.arch_sapphirerapids()
 // WINDOWS: ret i32 10
 // WINDOWS: define dso_local i32 @foo.arch_alderlake()
 // WINDOWS: ret i32 11
 // WINDOWS: define dso_local i32 @foo.arch_rocketlake()
 // WINDOWS: ret i32 12
+// WINDOWS: define dso_local i32 @foo.arch_core2()
+// WINDOWS: ret i32 13
 // WINDOWS: define dso_local i32 @foo()
 // WINDOWS: ret i32 2
 // WINDOWS: define dso_local i32 @bar()
 // WINDOWS: call i32 @foo.resolver()
 
 // LINUX: define weak_odr i32 ()* @foo.resolver() comdat
 // LINUX: call void @__cpu_indicator_init()
 // LINUX: ret i32 ()* @foo.arch_sandybridge

llvm/lib/Support/X86TargetParser.cpp

constexpr ProcInfo Processors[] = {
   { {"c3-2"}, CK_C3_2, ~0U, FeaturesPentium3 },
   { {"yonah"}, CK_Yonah, ~0U, FeaturesPrescott },
   // Netburst microarchitecture based processors.
   { {"pentium4"}, CK_Pentium4, ~0U, FeaturesPentium4 },
   { {"pentium4m"}, CK_Pentium4, ~0U, FeaturesPentium4 },
   { {"prescott"}, CK_Prescott, ~0U, FeaturesPrescott },
   { {"nocona"}, CK_Nocona, ~0U, FeaturesNocona },
   // Core microarchitecture based processors.
-  { {"core2"}, CK_Core2, ~0U, FeaturesCore2 },
+  { {"core2"}, CK_Core2, FEATURE_SSSE3, FeaturesCore2 },
   { {"penryn"}, CK_Penryn, ~0U, FeaturesPenryn },
   // Atom processors
   { {"bonnell"}, CK_Bonnell, FEATURE_SSSE3, FeaturesBonnell },
   { {"atom"}, CK_Bonnell, FEATURE_SSSE3, FeaturesBonnell },
   { {"silvermont"}, CK_Silvermont, FEATURE_SSE4_2, FeaturesSilvermont },
   { {"slm"}, CK_Silvermont, FEATURE_SSE4_2, FeaturesSilvermont },
   { {"goldmont"}, CK_Goldmont, FEATURE_SSE4_2, FeaturesGoldmont },
   { {"goldmont-plus"}, CK_GoldmontPlus, FEATURE_SSE4_2, FeaturesGoldmontPlus },