[X86] Move even more of our CPU to feature mapping switch to use fallthroughs

[craig.topper]

Summary

This arranges more of the Intel and AMD CPUs into fallthrough positions based on their features. We may be able to merge this new AMD set with the BTVER or BDVER sets but I didn't look that closely.

[RKSimon]

LGTM, there are a couple of other fall-throughs that could still be done.

lib/Basic/Targets/X86.cpp

141 ↗

(On Diff #115517)

CK_Pentium3/CK_C3_2/CK_PentiumM/CK_Pentium4/CK_x86_64 can be put below Yonah et al. (unless you're worried about including non-Intel enums)?

cfe/trunk/lib/Basic/Targets/X86.cpp

bool X86TargetInfo::initFeatureMap(
   case CK_i386:
   case CK_i486:
   case CK_i586:
   case CK_Pentium:
   case CK_i686:
   case CK_PentiumPro:
   case CK_Lakemont:
     break;
+
   case CK_PentiumMMX:
   case CK_Pentium2:
   case CK_K6:
   case CK_WinChipC6:
     setFeatureEnabledImpl(Features, "mmx", true);
     break;
-  case CK_Pentium3:
-  case CK_C3_2:
-    setFeatureEnabledImpl(Features, "sse", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    break;
-  case CK_PentiumM:
-  case CK_Pentium4:
-  case CK_x86_64:
-    setFeatureEnabledImpl(Features, "sse2", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    break;
-  case CK_Yonah:
-  case CK_Prescott:
-  case CK_Nocona:
-    setFeatureEnabledImpl(Features, "sse3", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    setFeatureEnabledImpl(Features, "cx16", true);
-    break;
-  case CK_Core2:
-    setFeatureEnabledImpl(Features, "ssse3", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    setFeatureEnabledImpl(Features, "cx16", true);
-    break;
-  case CK_Penryn:
-    setFeatureEnabledImpl(Features, "sse4.1", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    setFeatureEnabledImpl(Features, "cx16", true);
-    break;
+
   case CK_Cannonlake:
     setFeatureEnabledImpl(Features, "avx512ifma", true);
     setFeatureEnabledImpl(Features, "avx512vbmi", true);
     setFeatureEnabledImpl(Features, "sha", true);
     LLVM_FALLTHROUGH;
   case CK_SkylakeServer:
     setFeatureEnabledImpl(Features, "avx512f", true);
     setFeatureEnabledImpl(Features, "avx512cd", true);
case CK_SandyBridge:
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     LLVM_FALLTHROUGH;
   case CK_Westmere:
     setFeatureEnabledImpl(Features, "aes", true);
     setFeatureEnabledImpl(Features, "pclmul", true);
     LLVM_FALLTHROUGH;
   case CK_Nehalem:
     setFeatureEnabledImpl(Features, "sse4.2", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
+    LLVM_FALLTHROUGH;
+  case CK_Penryn:
+    setFeatureEnabledImpl(Features, "sse4.1", true);
+    LLVM_FALLTHROUGH;
+  case CK_Core2:
+    setFeatureEnabledImpl(Features, "ssse3", true);
+    LLVM_FALLTHROUGH;
+  case CK_Yonah:
+  case CK_Prescott:
+  case CK_Nocona:
+    setFeatureEnabledImpl(Features, "sse3", true);
     setFeatureEnabledImpl(Features, "cx16", true);
+    LLVM_FALLTHROUGH;
+  case CK_PentiumM:
+  case CK_Pentium4:
+  case CK_x86_64:
+    setFeatureEnabledImpl(Features, "sse2", true);
+    LLVM_FALLTHROUGH;
+  case CK_Pentium3:
+  case CK_C3_2:
+    setFeatureEnabledImpl(Features, "sse", true);
+    setFeatureEnabledImpl(Features, "fxsr", true);
     break;
+
   case CK_Goldmont:
     setFeatureEnabledImpl(Features, "sha", true);
     setFeatureEnabledImpl(Features, "rdrnd", true);
     setFeatureEnabledImpl(Features, "rdseed", true);
     setFeatureEnabledImpl(Features, "xsave", true);
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     setFeatureEnabledImpl(Features, "xsavec", true);
     setFeatureEnabledImpl(Features, "xsaves", true);
     setFeatureEnabledImpl(Features, "clflushopt", true);
     setFeatureEnabledImpl(Features, "mpx", true);
     LLVM_FALLTHROUGH;
   case CK_Silvermont:
     setFeatureEnabledImpl(Features, "aes", true);
     setFeatureEnabledImpl(Features, "pclmul", true);
     setFeatureEnabledImpl(Features, "sse4.2", true);
     LLVM_FALLTHROUGH;
   case CK_Bonnell:
     setFeatureEnabledImpl(Features, "movbe", true);
     setFeatureEnabledImpl(Features, "ssse3", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
     setFeatureEnabledImpl(Features, "cx16", true);
     break;
+
   case CK_KNL:
     setFeatureEnabledImpl(Features, "avx512f", true);
     setFeatureEnabledImpl(Features, "avx512cd", true);
     setFeatureEnabledImpl(Features, "avx512er", true);
     setFeatureEnabledImpl(Features, "avx512pf", true);
     setFeatureEnabledImpl(Features, "prefetchwt1", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
     setFeatureEnabledImpl(Features, "rdseed", true);
     setFeatureEnabledImpl(Features, "adx", true);
     setFeatureEnabledImpl(Features, "lzcnt", true);
     setFeatureEnabledImpl(Features, "bmi", true);
     setFeatureEnabledImpl(Features, "bmi2", true);
     setFeatureEnabledImpl(Features, "rtm", true);
     setFeatureEnabledImpl(Features, "fma", true);
     setFeatureEnabledImpl(Features, "rdrnd", true);
     setFeatureEnabledImpl(Features, "f16c", true);
     setFeatureEnabledImpl(Features, "fsgsbase", true);
     setFeatureEnabledImpl(Features, "aes", true);
     setFeatureEnabledImpl(Features, "pclmul", true);
     setFeatureEnabledImpl(Features, "cx16", true);
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     setFeatureEnabledImpl(Features, "xsave", true);
     setFeatureEnabledImpl(Features, "movbe", true);
     break;
+
   case CK_K6_2:
   case CK_K6_3:
   case CK_WinChip2:
   case CK_C3:
     setFeatureEnabledImpl(Features, "3dnow", true);
     break;
-  case CK_Athlon:
-  case CK_Geode:
-    setFeatureEnabledImpl(Features, "3dnowa", true);
-    break;
-  case CK_AthlonXP:
-    setFeatureEnabledImpl(Features, "sse", true);
-    setFeatureEnabledImpl(Features, "3dnowa", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    break;
-  case CK_K8:
-    setFeatureEnabledImpl(Features, "sse2", true);
-    setFeatureEnabledImpl(Features, "3dnowa", true);
-    setFeatureEnabledImpl(Features, "fxsr", true);
-    break;
+
   case CK_AMDFAM10:
     setFeatureEnabledImpl(Features, "sse4a", true);
     setFeatureEnabledImpl(Features, "lzcnt", true);
     setFeatureEnabledImpl(Features, "popcnt", true);
     LLVM_FALLTHROUGH;
   case CK_K8SSE3:
     setFeatureEnabledImpl(Features, "sse3", true);
-    setFeatureEnabledImpl(Features, "3dnowa", true);
+    LLVM_FALLTHROUGH;
+  case CK_K8:
+    setFeatureEnabledImpl(Features, "sse2", true);
+    LLVM_FALLTHROUGH;
+  case CK_AthlonXP:
+    setFeatureEnabledImpl(Features, "sse", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
+    LLVM_FALLTHROUGH;
+  case CK_Athlon:
+  case CK_Geode:
+    setFeatureEnabledImpl(Features, "3dnowa", true);
     break;
+
   case CK_BTVER2:
     setFeatureEnabledImpl(Features, "avx", true);
     setFeatureEnabledImpl(Features, "aes", true);
     setFeatureEnabledImpl(Features, "pclmul", true);
     setFeatureEnabledImpl(Features, "bmi", true);
     setFeatureEnabledImpl(Features, "f16c", true);
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     setFeatureEnabledImpl(Features, "movbe", true);
     LLVM_FALLTHROUGH;
   case CK_BTVER1:
     setFeatureEnabledImpl(Features, "ssse3", true);
     setFeatureEnabledImpl(Features, "sse4a", true);
     setFeatureEnabledImpl(Features, "lzcnt", true);
     setFeatureEnabledImpl(Features, "popcnt", true);
     setFeatureEnabledImpl(Features, "prfchw", true);
     setFeatureEnabledImpl(Features, "cx16", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
     break;
+
   case CK_ZNVER1:
     setFeatureEnabledImpl(Features, "adx", true);
     setFeatureEnabledImpl(Features, "aes", true);
     setFeatureEnabledImpl(Features, "avx2", true);
     setFeatureEnabledImpl(Features, "bmi", true);
     setFeatureEnabledImpl(Features, "bmi2", true);
     setFeatureEnabledImpl(Features, "clflushopt", true);
     setFeatureEnabledImpl(Features, "clzero", true);
case CK_ZNVER1:
     setFeatureEnabledImpl(Features, "rdseed", true);
     setFeatureEnabledImpl(Features, "sha", true);
     setFeatureEnabledImpl(Features, "sse4a", true);
     setFeatureEnabledImpl(Features, "xsave", true);
     setFeatureEnabledImpl(Features, "xsavec", true);
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     setFeatureEnabledImpl(Features, "xsaves", true);
     break;
+
   case CK_BDVER4:
     setFeatureEnabledImpl(Features, "avx2", true);
     setFeatureEnabledImpl(Features, "bmi2", true);
     setFeatureEnabledImpl(Features, "mwaitx", true);
     LLVM_FALLTHROUGH;
   case CK_BDVER3:
     setFeatureEnabledImpl(Features, "fsgsbase", true);
     setFeatureEnabledImpl(Features, "xsaveopt", true);