AsmPrinter: Make DIEString small

Expose the `DwarfStringPool` entry in a header, and store a pointer to
it directly in `DIEString`.  Instead of choosing at creation time how to
emit it, use the `dwarf::Form` to determine that at emission time.
Besides avoiding the other `DIEValue`, this shaves two pointers off of
`DIEString`; the data is now a single pointer.  This is a nice cleanup
on its own -- and drops memory usage from 861 MB down to 853 MB, around
0.9% -- but it's also preparation for passing `DIEValue`s by value.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 238117
diff --git a/llvm/unittests/CodeGen/DIEHashTest.cpp b/llvm/unittests/CodeGen/DIEHashTest.cpp
index efb0920..c1b1160 100644
--- a/llvm/unittests/CodeGen/DIEHashTest.cpp
+++ b/llvm/unittests/CodeGen/DIEHashTest.cpp
@@ -10,6 +10,7 @@
 #include "llvm/CodeGen/DIE.h"
 #include "../lib/CodeGen/AsmPrinter/DIEHash.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/DwarfStringPoolEntry.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Format.h"
@@ -18,7 +19,20 @@
 using namespace llvm;
 
 namespace {
-TEST(DIEHashTest, Data1) {
+
+// Test fixture
+class DIEHashTest : public testing::Test {
+  StringMap<DwarfStringPoolEntry> Pool;
+
+public:
+  DIEString getString(StringRef S) {
+    DwarfStringPoolEntry Entry = {nullptr, 1, 1};
+    return DIEString(
+        DwarfStringPoolEntryRef(*Pool.insert(std::make_pair(S, Entry)).first));
+  }
+};
+
+TEST_F(DIEHashTest, Data1) {
   DIEHash Hash;
   DIE Die(dwarf::DW_TAG_base_type);
   DIEInteger Size(4);
@@ -28,7 +42,7 @@
 }
 
 // struct {};
-TEST(DIEHashTest, TrivialType) {
+TEST_F(DIEHashTest, TrivialType) {
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
@@ -43,10 +57,10 @@
 }
 
 // struct foo { };
-TEST(DIEHashTest, NamedType) {
+TEST_F(DIEHashTest, NamedType) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
-  DIEString FooStr(&One, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
 
@@ -57,19 +71,19 @@
 }
 
 // namespace space { struct foo { }; }
-TEST(DIEHashTest, NamespacedType) {
+TEST_F(DIEHashTest, NamespacedType) {
   DIE CU(dwarf::DW_TAG_compile_unit);
 
   auto Space = make_unique<DIE>(dwarf::DW_TAG_namespace);
   DIEInteger One(1);
-  DIEString SpaceStr(&One, "space");
+  DIEString SpaceStr = getString("space");
   Space->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &SpaceStr);
   // DW_AT_declaration is ignored.
   Space->addValue(dwarf::DW_AT_declaration, dwarf::DW_FORM_flag_present, &One);
   // sibling?
 
   auto Foo = make_unique<DIE>(dwarf::DW_TAG_structure_type);
-  DIEString FooStr(&One, "foo");
+  DIEString FooStr = getString("foo");
   Foo->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
   Foo->addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
 
@@ -84,13 +98,13 @@
 }
 
 // struct { int member; };
-TEST(DIEHashTest, TypeWithMember) {
+TEST_F(DIEHashTest, TypeWithMember) {
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   DIEInteger Four(4);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Four);
 
   DIE Int(dwarf::DW_TAG_base_type);
-  DIEString IntStr(&Four, "int");
+  DIEString IntStr = getString("int");
   Int.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &IntStr);
   Int.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Four);
   DIEInteger Five(5);
@@ -99,7 +113,7 @@
   DIEEntry IntRef(Int);
 
   auto Member = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemberStr(&Four, "member");
+  DIEString MemberStr = getString("member");
   Member->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemberStr);
   DIEInteger Zero(0);
   Member->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
@@ -114,14 +128,14 @@
 }
 
 // struct foo { int mem1, mem2; };
-TEST(DIEHashTest, ReusedType) {
+TEST_F(DIEHashTest, ReusedType) {
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   DIEInteger Eight(8);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
 
   DIEInteger Four(4);
   DIE Int(dwarf::DW_TAG_base_type);
-  DIEString IntStr(&Four, "int");
+  DIEString IntStr = getString("int");
   Int.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &IntStr);
   Int.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Four);
   DIEInteger Five(5);
@@ -130,7 +144,7 @@
   DIEEntry IntRef(Int);
 
   auto Mem1 = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString Mem1Str(&Four, "mem1");
+  DIEString Mem1Str = getString("mem1");
   Mem1->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &Mem1Str);
   DIEInteger Zero(0);
   Mem1->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
@@ -140,7 +154,7 @@
   Unnamed.addChild(std::move(Mem1));
 
   auto Mem2 = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString Mem2Str(&Four, "mem2");
+  DIEString Mem2Str = getString("mem2");
   Mem2->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &Mem2Str);
   Mem2->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
                  &Four);
@@ -154,15 +168,15 @@
 }
 
 // struct foo { static foo f; };
-TEST(DIEHashTest, RecursiveType) {
+TEST_F(DIEHashTest, RecursiveType) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
-  DIEString FooStr(&One, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
 
   auto Mem = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemStr(&One, "mem");
+  DIEString MemStr = getString("mem");
   Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
   DIEEntry FooRef(Foo);
   Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &FooRef);
@@ -176,15 +190,15 @@
 }
 
 // struct foo { foo *mem; };
-TEST(DIEHashTest, Pointer) {
+TEST_F(DIEHashTest, Pointer) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger Eight(8);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
-  DIEString FooStr(&Eight, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
 
   auto Mem = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemStr(&Eight, "mem");
+  DIEString MemStr = getString("mem");
   Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
   DIEInteger Zero(0);
   Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1, &Zero);
@@ -205,15 +219,15 @@
 }
 
 // struct foo { foo &mem; };
-TEST(DIEHashTest, Reference) {
+TEST_F(DIEHashTest, Reference) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger Eight(8);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
-  DIEString FooStr(&Eight, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
 
   auto Mem = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemStr(&Eight, "mem");
+  DIEString MemStr = getString("mem");
   Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
   DIEInteger Zero(0);
   Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1, &Zero);
@@ -238,15 +252,15 @@
 }
 
 // struct foo { foo &&mem; };
-TEST(DIEHashTest, RValueReference) {
+TEST_F(DIEHashTest, RValueReference) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger Eight(8);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
-  DIEString FooStr(&Eight, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
 
   auto Mem = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemStr(&Eight, "mem");
+  DIEString MemStr = getString("mem");
   Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
   DIEInteger Zero(0);
   Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1, &Zero);
@@ -271,15 +285,15 @@
 }
 
 // struct foo { foo foo::*mem; };
-TEST(DIEHashTest, PtrToMember) {
+TEST_F(DIEHashTest, PtrToMember) {
   DIE Foo(dwarf::DW_TAG_structure_type);
   DIEInteger Eight(8);
   Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
-  DIEString FooStr(&Eight, "foo");
+  DIEString FooStr = getString("foo");
   Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
 
   auto Mem = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString MemStr(&Eight, "mem");
+  DIEString MemStr = getString("mem");
   Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
   DIEInteger Zero(0);
   Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1, &Zero);
@@ -305,13 +319,13 @@
 //
 //   struct bar; // { };
 //   struct foo { bar foo::*mem; };
-TEST(DIEHashTest, PtrToMemberDeclDefMatch) {
+TEST_F(DIEHashTest, PtrToMemberDeclDefMatch) {
   DIEInteger Zero(0);
   DIEInteger One(1);
   DIEInteger Eight(8);
-  DIEString FooStr(&Eight, "foo");
-  DIEString BarStr(&Eight, "bar");
-  DIEString MemStr(&Eight, "mem");
+  DIEString FooStr = getString("foo");
+  DIEString BarStr = getString("bar");
+  DIEString MemStr = getString("mem");
   uint64_t MD5ResDecl;
   {
     DIE Bar(dwarf::DW_TAG_structure_type);
@@ -378,13 +392,13 @@
 //
 //   struct bar; // { };
 //   struct foo { bar bar::*mem; };
-TEST(DIEHashTest, PtrToMemberDeclDefMisMatch) {
+TEST_F(DIEHashTest, PtrToMemberDeclDefMisMatch) {
   DIEInteger Zero(0);
   DIEInteger One(1);
   DIEInteger Eight(8);
-  DIEString FooStr(&Eight, "foo");
-  DIEString BarStr(&Eight, "bar");
-  DIEString MemStr(&Eight, "mem");
+  DIEString FooStr = getString("foo");
+  DIEString BarStr = getString("bar");
+  DIEString MemStr = getString("mem");
   uint64_t MD5ResDecl;
   {
     DIE Bar(dwarf::DW_TAG_structure_type);
@@ -451,12 +465,12 @@
 
 // struct { } a;
 // struct foo { decltype(a) mem; };
-TEST(DIEHashTest, RefUnnamedType) {
+TEST_F(DIEHashTest, RefUnnamedType) {
   DIEInteger Zero(0);
   DIEInteger One(1);
   DIEInteger Eight(8);
-  DIEString FooStr(&Zero, "foo");
-  DIEString MemStr(&Zero, "mem");
+  DIEString FooStr = getString("foo");
+  DIEString MemStr = getString("mem");
 
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
@@ -485,13 +499,13 @@
 }
 
 // struct { struct foo { }; };
-TEST(DIEHashTest, NestedType) {
+TEST_F(DIEHashTest, NestedType) {
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
 
   auto Foo = make_unique<DIE>(dwarf::DW_TAG_structure_type);
-  DIEString FooStr(&One, "foo");
+  DIEString FooStr = getString("foo");
   Foo->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
   Foo->addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
 
@@ -504,13 +518,13 @@
 }
 
 // struct { static void func(); };
-TEST(DIEHashTest, MemberFunc) {
+TEST_F(DIEHashTest, MemberFunc) {
   DIE Unnamed(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
   Unnamed.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
 
   auto Func = make_unique<DIE>(dwarf::DW_TAG_subprogram);
-  DIEString FuncStr(&One, "func");
+  DIEString FuncStr = getString("func");
   Func->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FuncStr);
 
   Unnamed.addChild(std::move(Func));
@@ -524,18 +538,18 @@
 // struct A {
 //   static void func();
 // };
-TEST(DIEHashTest, MemberFuncFlag) {
+TEST_F(DIEHashTest, MemberFuncFlag) {
   DIE A(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
-  DIEString AStr(&One, "A");
+  DIEString AStr = getString("A");
   A.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &AStr);
   A.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
   A.addValue(dwarf::DW_AT_decl_file, dwarf::DW_FORM_data1, &One);
   A.addValue(dwarf::DW_AT_decl_line, dwarf::DW_FORM_data1, &One);
 
   auto Func = make_unique<DIE>(dwarf::DW_TAG_subprogram);
-  DIEString FuncStr(&One, "func");
-  DIEString FuncLinkage(&One, "_ZN1A4funcEv");
+  DIEString FuncStr = getString("func");
+  DIEString FuncLinkage = getString("_ZN1A4funcEv");
   DIEInteger Two(2);
   Func->addValue(dwarf::DW_AT_external, dwarf::DW_FORM_flag_present, &One);
   Func->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FuncStr);
@@ -557,10 +571,10 @@
 //   const static int PI = -3;
 // };
 // A a;
-TEST(DIEHashTest, MemberSdata) {
+TEST_F(DIEHashTest, MemberSdata) {
   DIE A(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
-  DIEString AStr(&One, "A");
+  DIEString AStr = getString("A");
   A.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &AStr);
   A.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
   A.addValue(dwarf::DW_AT_decl_file, dwarf::DW_FORM_data1, &One);
@@ -568,7 +582,7 @@
 
   DIEInteger Four(4);
   DIEInteger Five(5);
-  DIEString FStr(&One, "int");
+  DIEString FStr = getString("int");
   DIE IntTyDIE(dwarf::DW_TAG_base_type);
   IntTyDIE.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Four);
   IntTyDIE.addValue(dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, &Five);
@@ -580,7 +594,7 @@
 
   DIEEntry PITy(*PITyDIE);
   auto PI = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString PIStr(&One, "PI");
+  DIEString PIStr = getString("PI");
   DIEInteger Two(2);
   DIEInteger NegThree(-3);
   PI->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &PIStr);
@@ -602,17 +616,17 @@
 //   const static float PI = 3.14;
 // };
 // A a;
-TEST(DIEHashTest, MemberBlock) {
+TEST_F(DIEHashTest, MemberBlock) {
   DIE A(dwarf::DW_TAG_structure_type);
   DIEInteger One(1);
-  DIEString AStr(&One, "A");
+  DIEString AStr = getString("A");
   A.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &AStr);
   A.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
   A.addValue(dwarf::DW_AT_decl_file, dwarf::DW_FORM_data1, &One);
   A.addValue(dwarf::DW_AT_decl_line, dwarf::DW_FORM_data1, &One);
 
   DIEInteger Four(4);
-  DIEString FStr(&One, "float");
+  DIEString FStr = getString("float");
   auto FloatTyDIE = make_unique<DIE>(dwarf::DW_TAG_base_type);
   FloatTyDIE->addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Four);
   FloatTyDIE->addValue(dwarf::DW_AT_encoding, dwarf::DW_FORM_data1, &Four);
@@ -624,7 +638,7 @@
 
   DIEEntry PITy(*PITyDIE);
   auto PI = make_unique<DIE>(dwarf::DW_TAG_member);
-  DIEString PIStr(&One, "PI");
+  DIEString PIStr = getString("PI");
   DIEInteger Two(2);
   PI->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &PIStr);
   PI->addValue(dwarf::DW_AT_decl_file, dwarf::DW_FORM_data1, &One);