[SubtargetFeatuers] Simplify the code used to imply features from CPU name.

If we make SetImpliedBits OR features outside of its loop, we can reuse it for the first round of implying features for CPUs.

llvm-svn: 355298

1 files changed, 7 insertions, 14 deletions

diff --git a/llvm/lib/MC/SubtargetFeature.cpp b/llvm/lib/MC/SubtargetFeature.cpp
index c34c6ff9007..84c743c5e33 100644
--- a/llvm/lib/MC/SubtargetFeature.cpp
+++ b/llvm/lib/MC/SubtargetFeature.cpp
@@ -124,12 +124,12 @@ std::string SubtargetFeatures::getString() const {
 static
 void SetImpliedBits(FeatureBitset &Bits, const FeatureBitset &Implies,
                     ArrayRef<SubtargetFeatureKV> FeatureTable) {
-  for (const SubtargetFeatureKV &FE : FeatureTable) {
-    if (Implies.test(FE.Value)) {
-      Bits.set(FE.Value);
+  // OR the Implies bits in outside the loop. This allows the Implies for CPUs
+  // which might imply features not in FeatureTable to use this.
+  Bits |= Implies;
+  for (const SubtargetFeatureKV &FE : FeatureTable)
+    if (Implies.test(FE.Value))
       SetImpliedBits(Bits, FE.Implies.getAsBitset(), FeatureTable);
-    }
-  }
 }
 
 /// For each feature that (transitively) implies this feature, clear it.
@@ -219,15 +219,8 @@ SubtargetFeatures::getFeatureBits(StringRef CPU,
 
     // If there is a match
     if (CPUEntry) {
-      // Set base feature bits
-      FeatureBitset CPUImplies = CPUEntry->Implies.getAsBitset();
-      Bits = CPUImplies;
-
-      // Set the feature implied by this CPU feature, if any.
-      for (auto &FE : FeatureTable) {
-        if (CPUImplies.test(FE.Value))
-          SetImpliedBits(Bits, FE.Implies.getAsBitset(), FeatureTable);
-      }
+      // Set the features implied by this CPU feature, if any.
+      SetImpliedBits(Bits, CPUEntry->Implies.getAsBitset(), FeatureTable);
     } else {
       errs() << "'" << CPU << "' is not a recognized processor for this target"
              << " (ignoring processor)\n";