From: Alexander Shaposhnikov <shal1t712@gmail.com>
Date: Wed, 5 Jul 2017 20:14:54 +0000 (+0000)
Subject: [tablegen] Avoid creating temporary strings
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=18b16185df9a77102fd4b52821f76da8a93529d6;p=llvm

[tablegen] Avoid creating temporary strings

If a method / function returns a StringRef but the
variable is of type const std::string& a temporary string is
created (StringRef has a cast operator to std::string),
which is a suboptimal behavior.

Differential revision: https://reviews.llvm.org/D34994

Test plan: make check-all


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307195 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/utils/TableGen/FixedLenDecoderEmitter.cpp b/utils/TableGen/FixedLenDecoderEmitter.cpp
index 75fd73082b9..03930d7132d 100644
--- a/utils/TableGen/FixedLenDecoderEmitter.cpp
+++ b/utils/TableGen/FixedLenDecoderEmitter.cpp
@@ -1691,9 +1691,7 @@ void FilterChooser::emitTableEntries(DecoderTableInfo &TableInfo) const {
   dumpStack(errs(), "\t\t");
 
   for (unsigned i = 0; i < Opcodes.size(); ++i) {
-    const std::string &Name = nameWithID(Opcodes[i]);
-
-    errs() << '\t' << Name << " ";
+    errs() << '\t' << nameWithID(Opcodes[i]) << " ";
     dumpBits(errs(),
              getBitsField(*AllInstructions[Opcodes[i]]->TheDef, "Inst"));
     errs() << '\n';
diff --git a/utils/TableGen/SearchableTableEmitter.cpp b/utils/TableGen/SearchableTableEmitter.cpp
index efd4e83eca9..f73c197dee5 100644
--- a/utils/TableGen/SearchableTableEmitter.cpp
+++ b/utils/TableGen/SearchableTableEmitter.cpp
@@ -230,7 +230,7 @@ void SearchableTableEmitter::emitLookupDeclaration(StringRef Name,
 
 void SearchableTableEmitter::emitMapping(Record *InstanceClass,
                                          raw_ostream &OS) {
-  const std::string &TableName = InstanceClass->getName();
+  StringRef TableName = InstanceClass->getName();
   std::vector<Record *> Items = Records.getAllDerivedDefinitions(TableName);
 
   // Gather all the records we're going to need for this particular mapping.
@@ -265,8 +265,8 @@ void SearchableTableEmitter::emitMapping(Record *InstanceClass,
     ++Idx;
   }
 
-  OS << "#ifdef GET_" << StringRef(TableName).upper() << "_DECL\n";
-  OS << "#undef GET_" << StringRef(TableName).upper() << "_DECL\n";
+  OS << "#ifdef GET_" << TableName.upper() << "_DECL\n";
+  OS << "#undef GET_" << TableName.upper() << "_DECL\n";
 
   // Next emit the enum containing the top-level names for use in C++ code if
   // requested
@@ -281,8 +281,8 @@ void SearchableTableEmitter::emitMapping(Record *InstanceClass,
 
   OS << "#endif\n\n";
 
-  OS << "#ifdef GET_" << StringRef(TableName).upper() << "_IMPL\n";
-  OS << "#undef GET_" << StringRef(TableName).upper() << "_IMPL\n";
+  OS << "#ifdef GET_" << TableName.upper() << "_IMPL\n";
+  OS << "#undef GET_" << TableName.upper() << "_IMPL\n";
 
   // The primary data table contains all the fields defined for this map.
   emitPrimaryTable(TableName, FieldNames, SearchFieldNames, SearchTables, Items,
diff --git a/utils/TableGen/SubtargetEmitter.cpp b/utils/TableGen/SubtargetEmitter.cpp
index 16d5740b79a..d1d873b66aa 100644
--- a/utils/TableGen/SubtargetEmitter.cpp
+++ b/utils/TableGen/SubtargetEmitter.cpp
@@ -375,7 +375,7 @@ EmitStageAndOperandCycleData(raw_ostream &OS,
     if (FUs.empty())
       continue;
 
-    const std::string &Name = ProcModel.ItinsDef->getName();
+    StringRef Name = ProcModel.ItinsDef->getName();
     OS << "\n// Functional units for \"" << Name << "\"\n"
        << "namespace " << Name << "FU {\n";
 
@@ -429,7 +429,7 @@ EmitStageAndOperandCycleData(raw_ostream &OS,
     if (!ProcModel.hasItineraries())
       continue;
 
-    const std::string &Name = ProcModel.ItinsDef->getName();
+    StringRef Name = ProcModel.ItinsDef->getName();
 
     ItinList.resize(SchedModels.numInstrSchedClasses());
     assert(ProcModel.ItinDefList.size() == ItinList.size() && "bad Itins");
@@ -546,9 +546,6 @@ EmitItineraries(raw_ostream &OS,
     if (!ItinsDefSet.insert(ItinsDef).second)
       continue;
 
-    // Get processor itinerary name
-    const std::string &Name = ItinsDef->getName();
-
     // Get the itinerary list for the processor.
     assert(ProcItinListsIter != ProcItinLists.end() && "bad iterator");
     std::vector<InstrItinerary> &ItinList = *ProcItinListsIter;
@@ -562,7 +559,7 @@ EmitItineraries(raw_ostream &OS,
     OS << "static const llvm::InstrItinerary ";
 
     // Begin processor itinerary table
-    OS << Name << "[] = {\n";
+    OS << ItinsDef->getName() << "[] = {\n";
 
     // For each itinerary class in CodeGenSchedClass::Index order.
     for (unsigned j = 0, M = ItinList.size(); j < M; ++j) {
diff --git a/utils/TableGen/X86RecognizableInstr.cpp b/utils/TableGen/X86RecognizableInstr.cpp
index 570c677a391..202a71ae4dc 100644
--- a/utils/TableGen/X86RecognizableInstr.cpp
+++ b/utils/TableGen/X86RecognizableInstr.cpp
@@ -367,7 +367,7 @@ void RecognizableInstr::handleOperand(bool optional, unsigned &operandIndex,
     ++operandIndex;
   }
 
-  const std::string &typeName = (*Operands)[operandIndex].Rec->getName();
+  StringRef typeName = (*Operands)[operandIndex].Rec->getName();
 
   OperandEncoding encoding = encodingFromString(typeName, OpSize);
   // Adjust the encoding type for an operand based on the instruction.