Revert "Revert "[JITLink] Use MapVector to stabilize iteration order""

This reverts commit 244ea40 while I test a fix
for a build failure: https://lab.llvm.org/buildbot/#/builders/174/builds/7685.

Author: lhames

llvm/include/llvm/ExecutionEngine/JITLink/JITLink.h

@@ -15,6 +15,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/FunctionExtras.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
@@ -853,7 +854,7 @@ class SectionRange {
 
 class LinkGraph {
 private:
-  using SectionMap = DenseMap<StringRef, std::unique_ptr<Section>>;
+  using SectionMap = MapVector<StringRef, std::unique_ptr<Section>>;
   using ExternalSymbolMap = StringMap<Symbol *>;
   using AbsoluteSymbolSet = DenseSet<Symbol *>;
   using BlockSet = DenseSet<Block *>;
@@ -1595,7 +1596,7 @@ class LinkGraph {
   unsigned PointerSize;
   llvm::endianness Endianness;
   GetEdgeKindNameFunction GetEdgeKindName = nullptr;
-  DenseMap<StringRef, std::unique_ptr<Section>> Sections;
+  MapVector<StringRef, std::unique_ptr<Section>> Sections;
   ExternalSymbolMap ExternalSymbols;
   AbsoluteSymbolSet AbsoluteSymbols;
   orc::shared::AllocActions AAs;

llvm/lib/ExecutionEngine/JITLink/JITLink.cpp

@@ -291,18 +291,11 @@ void LinkGraph::dump(raw_ostream &OS) {
       return false;
     });
 
-  std::vector<Section *> SortedSections;
-  for (auto &Sec : sections())
-    SortedSections.push_back(&Sec);
-  llvm::sort(SortedSections, [](const Section *LHS, const Section *RHS) {
-    return LHS->getName() < RHS->getName();
-  });
-
-  for (auto *Sec : SortedSections) {
-    OS << "section " << Sec->getName() << ":\n\n";
+  for (auto &Sec : sections()) {
+    OS << "section " << Sec.getName() << ":\n\n";
 
     std::vector<Block *> SortedBlocks;
-    llvm::copy(Sec->blocks(), std::back_inserter(SortedBlocks));
+    llvm::copy(Sec.blocks(), std::back_inserter(SortedBlocks));
     llvm::sort(SortedBlocks, [](const Block *LHS, const Block *RHS) {
       return LHS->getAddress() < RHS->getAddress();
     });

llvm/test/ExecutionEngine/JITLink/x86-64/COFF_comdat_associative_dead_strip.test

@@ -7,10 +7,10 @@
 # parent block is dead.
 #
 # CHECK: Link graph
-# CHECK-DAG: section child:
-# CHECK-EMPTY:
 # CHECK-DAG: section parent:
 # CHECK-EMPTY:
+# CHECK-DAG: section child:
+# CHECK-EMPTY:
 
 --- !COFF
 header:

llvm/test/ExecutionEngine/JITLink/x86-64/COFF_pdata_strip.s

@@ -8,9 +8,9 @@
 #
 # CHECK: section .func:
 # CHECK-EMPTY:
-# CHECK-NEXT: section .pdata:
+# CHECK-NEXT: section .xdata:
 # CHECK-EMPTY:
-# CHECK: section .xdata:
+# CHECK-NEXT: section .pdata:
 # CHECK-EMPTY:
 
 	.text