[llvm] r354243 - [MC] Make SubtargetFeatureKV only store one FeatureBitset and use an 'unsigned' to hold the value.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sun Feb 17 22:46:17 2019
New Revision: 354243

URL: http://llvm.org/viewvc/llvm-project?rev=354243&view=rev
Log:
[MC] Make SubtargetFeatureKV only store one FeatureBitset and use an 'unsigned' to hold the value.

This class is used for two difference tablegen generated tables. For one of the tables the Value FeatureBitset only has one bit set. For the other usage the Implies field was unused.

This patch changes the Value field to just be an unsigned. For the usage that put a real vector in bitset, we now use the previously unused Implies field and leave the Value field unused instead.

This is good for a 16K reduction in the size of llc on my local build with all targets enabled.

Modified:
    llvm/trunk/include/llvm/MC/SubtargetFeature.h
    llvm/trunk/lib/MC/SubtargetFeature.cpp
    llvm/trunk/utils/TableGen/SubtargetEmitter.cpp

Modified: llvm/trunk/include/llvm/MC/SubtargetFeature.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/SubtargetFeature.h?rev=354243&r1=354242&r2=354243&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/SubtargetFeature.h (original)
+++ llvm/trunk/include/llvm/MC/SubtargetFeature.h Sun Feb 17 22:46:17 2019
@@ -52,7 +52,7 @@ public:
 struct SubtargetFeatureKV {
   const char *Key;                      ///< K-V key string
   const char *Desc;                     ///< Help descriptor
-  FeatureBitset Value;                  ///< K-V integer value
+  unsigned Value;                       ///< K-V integer value
   FeatureBitset Implies;                ///< K-V bit mask
 
   /// Compare routine for std::lower_bound

Modified: llvm/trunk/lib/MC/SubtargetFeature.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/SubtargetFeature.cpp?rev=354243&r1=354242&r2=354243&view=diff
==============================================================================
--- llvm/trunk/lib/MC/SubtargetFeature.cpp (original)
+++ llvm/trunk/lib/MC/SubtargetFeature.cpp Sun Feb 17 22:46:17 2019
@@ -127,8 +127,8 @@ void SetImpliedBits(FeatureBitset &Bits,
   for (const SubtargetFeatureKV &FE : FeatureTable) {
     if (FeatureEntry.Value == FE.Value) continue;
 
-    if ((FeatureEntry.Implies & FE.Value).any()) {
-      Bits |= FE.Value;
+    if (FeatureEntry.Implies.test(FE.Value)) {
+      Bits.set(FE.Value);
       SetImpliedBits(Bits, FE, FeatureTable);
     }
   }
@@ -142,8 +142,8 @@ void ClearImpliedBits(FeatureBitset &Bit
   for (const SubtargetFeatureKV &FE : FeatureTable) {
     if (FeatureEntry.Value == FE.Value) continue;
 
-    if ((FE.Implies & FeatureEntry.Value).any()) {
-      Bits &= ~FE.Value;
+    if (FE.Implies.test(FeatureEntry.Value)) {
+      Bits.reset(FE.Value);
       ClearImpliedBits(Bits, FE, FeatureTable);
     }
   }
@@ -157,12 +157,12 @@ SubtargetFeatures::ToggleFeature(Feature
       Find(StripFlag(Feature), FeatureTable);
   // If there is a match
   if (FeatureEntry) {
-    if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
-      Bits &= ~FeatureEntry->Value;
+    if (Bits.test(FeatureEntry->Value)) {
+      Bits.reset(FeatureEntry->Value);
       // For each feature that implies this, clear it.
       ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
     } else {
-      Bits |=  FeatureEntry->Value;
+      Bits.set(FeatureEntry->Value);
 
       // For each feature that this implies, set it.
       SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
@@ -184,12 +184,12 @@ void SubtargetFeatures::ApplyFeatureFlag
   if (FeatureEntry) {
     // Enable/disable feature in bits
     if (isEnabled(Feature)) {
-      Bits |= FeatureEntry->Value;
+      Bits.set(FeatureEntry->Value);
 
       // For each feature that this implies, set it.
       SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
     } else {
-      Bits &= ~FeatureEntry->Value;
+      Bits.reset(FeatureEntry->Value);
 
       // For each feature that implies this, clear it.
       ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
@@ -225,11 +225,11 @@ SubtargetFeatures::getFeatureBits(String
     // If there is a match
     if (CPUEntry) {
       // Set base feature bits
-      Bits = CPUEntry->Value;
+      Bits = CPUEntry->Implies;
 
       // Set the feature implied by this CPU feature, if any.
       for (auto &FE : FeatureTable) {
-        if ((CPUEntry->Value & FE.Value).any())
+        if (CPUEntry->Implies.test(FE.Value))
           SetImpliedBits(Bits, FE, FeatureTable);
       }
     } else {

Modified: llvm/trunk/utils/TableGen/SubtargetEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/SubtargetEmitter.cpp?rev=354243&r1=354242&r2=354243&view=diff
==============================================================================
--- llvm/trunk/utils/TableGen/SubtargetEmitter.cpp (original)
+++ llvm/trunk/utils/TableGen/SubtargetEmitter.cpp Sun Feb 17 22:46:17 2019
@@ -203,7 +203,7 @@ unsigned SubtargetEmitter::FeatureKeyVal
     OS << "  { "
        << "\"" << CommandLineName << "\", "
        << "\"" << Desc << "\", "
-       << "{ " << Target << "::" << Name << " }, ";
+       << Target << "::" << Name << ", ";
 
     RecVec ImpliesList = Feature->getValueAsListOfDefs("Implies");
 
@@ -242,18 +242,18 @@ unsigned SubtargetEmitter::CPUKeyValues(
     StringRef Name = Processor->getValueAsString("Name");
     RecVec FeatureList = Processor->getValueAsListOfDefs("Features");
 
-    // Emit as { "cpu", "description", { f1 , f2 , ... fn } },
-    OS << "  { "
+    // Emit as { "cpu", "description", 0, { f1 , f2 , ... fn } },
+    // The 0 is for the feature id which isn't used for CPUs.
+    OS << " { "
        << "\"" << Name << "\", "
-       << "\"Select the " << Name << " processor\", ";
+       << "\"Select the " << Name << " processor\", 0, ";
 
     OS << "{";
     for (unsigned j = 0, M = FeatureList.size(); j < M;) {
       OS << " " << Target << "::" << FeatureList[j]->getName();
       if (++j < M) OS << ",";
     }
-    // The { } is for the "implies" section of this data structure.
-    OS << " }, { } },\n";
+    OS << " } },\n";
   }
 
   // End processor table