1 files changed, 54 insertions, 18 deletions

diff --git a/lib/MC/SubtargetFeature.cpp b/lib/MC/SubtargetFeature.cpp
index b9caece..348cd4c 100644
--- a/lib/MC/SubtargetFeature.cpp
+++ b/lib/MC/SubtargetFeature.cpp
@@ -224,6 +224,38 @@ void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
   }
 }
 
+/// ToggleFeature - Toggle a feature and returns the newly updated feature
+/// bits.
+uint64_t
+SubtargetFeatures::ToggleFeature(uint64_t Bits, const StringRef Feature,
+                                 const SubtargetFeatureKV *FeatureTable,
+                                 size_t FeatureTableSize) {
+  // Find feature in table.
+  const SubtargetFeatureKV *FeatureEntry =
+    Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
+  // If there is a match
+  if (FeatureEntry) {
+    if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
+      Bits &= ~FeatureEntry->Value;
+
+      // For each feature that implies this, clear it.
+      ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
+    } else {
+      Bits |=  FeatureEntry->Value;
+
+      // For each feature that this implies, set it.
+      SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
+    }
+  } else {
+    errs() << "'" << Feature
+           << "' is not a recognized feature for this target"
+           << " (ignoring feature)\n";
+  }
+
+  return Bits;
+}
+           
+
 /// getFeatureBits - Get feature bits a CPU.
 ///
 uint64_t SubtargetFeatures::getFeatureBits(const StringRef CPU,
@@ -231,8 +263,9 @@ uint64_t SubtargetFeatures::getFeatureBits(const StringRef CPU,
                                          size_t CPUTableSize,
                                          const SubtargetFeatureKV *FeatureTable,
                                          size_t FeatureTableSize) {
-  assert(CPUTable && "missing CPU table");
-  assert(FeatureTable && "missing features table");
+  if (!FeatureTableSize || !CPUTableSize)
+    return 0;
+
 #ifndef NDEBUG
   for (size_t i = 1; i < CPUTableSize; i++) {
     assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
@@ -249,24 +282,27 @@ uint64_t SubtargetFeatures::getFeatureBits(const StringRef CPU,
   if (CPU == "help")
     Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
   
-  // Find CPU entry
-  const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable, CPUTableSize);
-  // If there is a match
-  if (CPUEntry) {
-    // Set base feature bits
-    Bits = CPUEntry->Value;
-
-    // Set the feature implied by this CPU feature, if any.
-    for (size_t i = 0; i < FeatureTableSize; ++i) {
-      const SubtargetFeatureKV &FE = FeatureTable[i];
-      if (CPUEntry->Value & FE.Value)
-        SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
+  // Find CPU entry if CPU name is specified.
+  if (!CPU.empty()) {
+    const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable, CPUTableSize);
+    // If there is a match
+    if (CPUEntry) {
+      // Set base feature bits
+      Bits = CPUEntry->Value;
+
+      // Set the feature implied by this CPU feature, if any.
+      for (size_t i = 0; i < FeatureTableSize; ++i) {
+        const SubtargetFeatureKV &FE = FeatureTable[i];
+        if (CPUEntry->Value & FE.Value)
+          SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
+      }
+    } else {
+      errs() << "'" << CPU
+             << "' is not a recognized processor for this target"
+             << " (ignoring processor)\n";
     }
-  } else {
-    errs() << "'" << CPU
-           << "' is not a recognized processor for this target"
-           << " (ignoring processor)\n";
   }
+
   // Iterate through each feature
   for (size_t i = 0, E = Features.size(); i < E; i++) {
     const StringRef Feature = Features[i];