Switch SmallSetVector to use DenseSet when it overflows its inline space.

Summary:
SetVector already used DenseSet, but SmallSetVector used std::set.  This
leads to surprising performance differences.  Moreover, it means that
the set of key types accepted by SetVector and SmallSetVector are
quite different!

In order to make this change, we had to convert some callsites that used
SmallSetVector<std::string, N> to use SmallSetVector<CachedHashString, N>
instead.

Reviewers: timshen

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25648

llvm-svn: 284887

1 files changed, 6 insertions, 5 deletions

diff --git a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
index d0c4e0fd2f9..f2d54e6fe5a 100644
--- a/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
+++ b/llvm/utils/TableGen/FixedLenDecoderEmitter.cpp
@@ -14,6 +14,7 @@
 
 #include "CodeGenTarget.h"
 #include "llvm/ADT/APInt.h"
+#include "llvm/ADT/CachedHashString.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
@@ -66,8 +67,8 @@ typedef std::vector<uint8_t> DecoderTable;
 typedef uint32_t DecoderFixup;
 typedef std::vector<DecoderFixup> FixupList;
 typedef std::vector<FixupList> FixupScopeList;
-typedef SmallSetVector<std::string, 16> PredicateSet;
-typedef SmallSetVector<std::string, 16> DecoderSet;
+typedef SmallSetVector<CachedHashString, 16> PredicateSet;
+typedef SmallSetVector<CachedHashString, 16> DecoderSet;
 struct DecoderTableInfo {
   DecoderTable Table;
   FixupScopeList FixupStack;
@@ -1106,7 +1107,7 @@ unsigned FilterChooser::getDecoderIndex(DecoderSet &Decoders,
   // overkill for now, though.
 
   // Make sure the predicate is in the table.
-  Decoders.insert(StringRef(Decoder));
+  Decoders.insert(CachedHashString(Decoder));
   // Now figure out the index for when we write out the table.
   DecoderSet::const_iterator P = find(Decoders, Decoder.str());
   return (unsigned)(P - Decoders.begin());
@@ -1179,9 +1180,9 @@ unsigned FilterChooser::getPredicateIndex(DecoderTableInfo &TableInfo,
   // overkill for now, though.
 
   // Make sure the predicate is in the table.
-  TableInfo.Predicates.insert(Predicate.str());
+  TableInfo.Predicates.insert(CachedHashString(Predicate));
   // Now figure out the index for when we write out the table.
-  PredicateSet::const_iterator P = find(TableInfo.Predicates, Predicate.str());
+  PredicateSet::const_iterator P = find(TableInfo.Predicates, Predicate);
   return (unsigned)(P - TableInfo.Predicates.begin());
 }