Simplify arange output.

Move SectionMap to its only user (emitDebugARanges) and
reorder to save a call to sort.

llvm-svn: 230693

1 files changed, 43 insertions, 60 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index eb4df82093e..aa1f79f260a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -490,9 +490,6 @@ void DwarfDebug::beginModule() {
 
   // Tell MMI that we have debug info.
   MMI->setDebugInfoAvailability(true);
-
-  // Prime section data.
-  SectionMap[Asm->getObjFileLowering().getTextSection()];
 }
 
 void DwarfDebug::finishVariableDefinitions() {
@@ -608,53 +605,6 @@ void DwarfDebug::finalizeModuleInfo() {
     SkeletonHolder.computeSizeAndOffsets();
 }
 
-void DwarfDebug::endSections() {
-  // Filter labels by section.
-  for (const SymbolCU &SCU : ArangeLabels) {
-    if (SCU.Sym->isInSection()) {
-      // Make a note of this symbol and it's section.
-      const MCSection *Section = &SCU.Sym->getSection();
-      if (!Section->getKind().isMetadata())
-        SectionMap[Section].push_back(SCU);
-    } else {
-      // Some symbols (e.g. common/bss on mach-o) can have no section but still
-      // appear in the output. This sucks as we rely on sections to build
-      // arange spans. We can do it without, but it's icky.
-      SectionMap[nullptr].push_back(SCU);
-    }
-  }
-
-  // Build a list of sections used.
-  std::vector<const MCSection *> Sections;
-  for (const auto &it : SectionMap) {
-    const MCSection *Section = it.first;
-    Sections.push_back(Section);
-  }
-
-  // Sort the sections into order.
-  // This is only done to ensure consistent output order across different runs.
-  std::sort(Sections.begin(), Sections.end(), SectionSort);
-
-  // Add terminating symbols for each section.
-  for (unsigned ID = 0, E = Sections.size(); ID != E; ID++) {
-    const MCSection *Section = Sections[ID];
-    MCSymbol *Sym = nullptr;
-
-    if (Section) {
-      // We can't call MCSection::getLabelEndName, as it's only safe to do so
-      // if we know the section name up-front. For user-created sections, the
-      // resulting label may not be valid to use as a label. (section names can
-      // use a greater set of characters on some systems)
-      Sym = Asm->GetTempSymbol("debug_end", ID);
-      Asm->OutStreamer.SwitchSection(Section);
-      Asm->OutStreamer.EmitLabel(Sym);
-    }
-
-    // Insert a final terminator.
-    SectionMap[Section].push_back(SymbolCU(nullptr, Sym));
-  }
-}
-
 // Emit all Dwarf sections that should come after the content.
 void DwarfDebug::endModule() {
   assert(CurFn == nullptr);
@@ -666,10 +616,6 @@ void DwarfDebug::endModule() {
   if (!DwarfInfoSectionSym)
     return;
 
-  // End any existing sections.
-  // TODO: Does this need to happen?
-  endSections();
-
   // Finalize the debug info for the module.
   finalizeModuleInfo();
 
@@ -1805,13 +1751,26 @@ struct ArangeSpan {
 // Emit a debug aranges section, containing a CU lookup for any
 // address we can tie back to a CU.
 void DwarfDebug::emitDebugARanges() {
-  // Start the dwarf aranges section.
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfARangesSection());
+  // Provides a unique id per text section.
+  DenseMap<const MCSection *, SmallVector<SymbolCU, 8>> SectionMap;
 
-  typedef DenseMap<DwarfCompileUnit *, std::vector<ArangeSpan>> SpansType;
+  // Prime section data.
+  SectionMap[Asm->getObjFileLowering().getTextSection()];
 
-  SpansType Spans;
+  // Filter labels by section.
+  for (const SymbolCU &SCU : ArangeLabels) {
+    if (SCU.Sym->isInSection()) {
+      // Make a note of this symbol and it's section.
+      const MCSection *Section = &SCU.Sym->getSection();
+      if (!Section->getKind().isMetadata())
+        SectionMap[Section].push_back(SCU);
+    } else {
+      // Some symbols (e.g. common/bss on mach-o) can have no section but still
+      // appear in the output. This sucks as we rely on sections to build
+      // arange spans. We can do it without, but it's icky.
+      SectionMap[nullptr].push_back(SCU);
+    }
+  }
 
   // Build a list of sections used.
   std::vector<const MCSection *> Sections;
@@ -1824,7 +1783,27 @@ void DwarfDebug::emitDebugARanges() {
   // This is only done to ensure consistent output order across different runs.
   std::sort(Sections.begin(), Sections.end(), SectionSort);
 
-  // Build a set of address spans, sorted by CU.
+  // Add terminating symbols for each section.
+  for (unsigned ID = 0, E = Sections.size(); ID != E; ID++) {
+    const MCSection *Section = Sections[ID];
+    MCSymbol *Sym = nullptr;
+
+    if (Section) {
+      // We can't call MCSection::getLabelEndName, as it's only safe to do so
+      // if we know the section name up-front. For user-created sections, the
+      // resulting label may not be valid to use as a label. (section names can
+      // use a greater set of characters on some systems)
+      Sym = Asm->GetTempSymbol("debug_end", ID);
+      Asm->OutStreamer.SwitchSection(Section);
+      Asm->OutStreamer.EmitLabel(Sym);
+    }
+
+    // Insert a final terminator.
+    SectionMap[Section].push_back(SymbolCU(nullptr, Sym));
+  }
+
+  DenseMap<DwarfCompileUnit *, std::vector<ArangeSpan>> Spans;
+
   for (const MCSection *Section : Sections) {
     SmallVector<SymbolCU, 8> &List = SectionMap[Section];
     if (List.size() < 2)
@@ -1875,6 +1854,10 @@ void DwarfDebug::emitDebugARanges() {
     }
   }
 
+  // Start the dwarf aranges section.
+  Asm->OutStreamer.SwitchSection(
+      Asm->getObjFileLowering().getDwarfARangesSection());
+
   unsigned PtrSize = Asm->getDataLayout().getPointerSize();
 
   // Build a list of CUs used.