Improve name handling in MachRegister (#1612)

* Clean up name caching in MachRegister

This just needs to be a file-scope static. It also doesn't need to be
allocated on the heap or be an ordered container.

* Fix broken transient include

* Have 'name' return ref to const

No need to make a copy.

* Add back error handling for missing name

common/h/registers/MachRegister.h

@@ -34,8 +34,6 @@
 #include "Architecture.h"
 #include "util.h"
 
-#include <boost/shared_ptr.hpp>
-#include <map>
 #include <string>
 
 namespace Dyninst {
@@ -45,9 +43,6 @@ namespace Dyninst {
   private:
     signed int reg;
 
-    typedef std::map<signed int, std::string> NameMap;
-    static boost::shared_ptr<MachRegister::NameMap> names();
-
   public:
     MachRegister();
     explicit MachRegister(signed int r);
@@ -58,7 +53,7 @@ namespace Dyninst {
     bool isValid() const;
     MachRegisterVal getSubRegValue(const MachRegister& subreg, MachRegisterVal& orig) const;
 
-    std::string name() const;
+    std::string const& name() const;
     unsigned int size() const;
     bool operator<(const MachRegister& a) const;
     bool operator==(const MachRegister& a) const;

common/src/registers/MachRegister.C

@@ -7,19 +7,20 @@
 #include "external/rose/rose-compat.h"
 
 #include <cassert>
+#include <unordered_map>
+
+namespace {
+  std::unordered_map<signed int, std::string> names;
+  const std::string invalid_reg_name{"<INVALID_REG>"};
+}
 
 namespace Dyninst {
-  boost::shared_ptr<MachRegister::NameMap> MachRegister::names() {
-    static boost::shared_ptr<MachRegister::NameMap> store =
-        boost::shared_ptr<MachRegister::NameMap>(new MachRegister::NameMap);
-    return store;
-  }
 
   MachRegister::MachRegister() : reg(0) {}
 
   MachRegister::MachRegister(signed int r) : reg(r) {}
 
-  MachRegister::MachRegister(signed int r, std::string n) : reg(r) { (*names())[r] = n; }
+  MachRegister::MachRegister(signed int r, std::string n) : reg(r) { names.emplace(r, std::move(n)); }
 
   unsigned int MachRegister::regClass() const { return reg & 0x00ff0000; }
 
@@ -100,16 +101,13 @@ namespace Dyninst {
     }
   }
 
-  std::string MachRegister::name() const {
-    assert(names() != NULL);
-    NameMap::const_iterator iter = names()->find(reg);
-
-    std::string ret;
-    if(iter != names()->end()) {
-      return iter->second;
+  std::string const& MachRegister::name() const {
+    auto iter = names.find(reg);
+    if(iter != names.end()) {
+	return iter->second;
     }
-    common_parsing_printf(" can't find register with index %x\n", (unsigned int)reg);
-    return std::string("<INVALID_REG>");
+    common_parsing_printf("No MachRegister found with value %x\n", static_cast<unsigned int>(reg));
+    return invalid_reg_name;
   }
 
   unsigned int MachRegister::size() const {

instructionAPI/src/ArchSpecificFormatters.C

@@ -12,6 +12,7 @@
 #include <string.h>
 #include <assert.h>
 #include <boost/algorithm/string/join.hpp>
+#include <boost/shared_ptr.hpp>
 #include "../../common/h/compiler_diagnostics.h"
 #include "Architecture.h"
 #include "registers/AMDGPU/amdgpu_gfx908_regs.h"