[lld][ELF] Assign sectionChoice properly to ELF atoms

This sets the sectionChoice property for DefinedAtoms. The output section name
is derived by the property of the atom. This also decreases native file size.

Adds a test.

llvm-svn: 190840

5 files changed, 61 insertions, 38 deletions

diff --git a/lld/lib/ReaderWriter/ELF/Atoms.h b/lld/lib/ReaderWriter/ELF/Atoms.h
index 6321a550774..27521667bad 100644
--- a/lld/lib/ReaderWriter/ELF/Atoms.h
+++ b/lld/lib/ReaderWriter/ELF/Atoms.h
@@ -16,6 +16,7 @@
 #include "lld/ReaderWriter/Simple.h"
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringSwitch.h"
 
 #include <memory>
 #include <vector>
@@ -376,9 +377,20 @@ public:
 
   // Do we have a choice for ELF?  All symbols live in explicit sections.
   virtual SectionChoice sectionChoice() const {
-    if (_symbol->st_shndx > llvm::ELF::SHN_LORESERVE)
-      return sectionBasedOnContent;
-
+    switch (contentType()) {
+    case typeCode:
+    case typeData:
+    case typeZeroFill:
+    case typeThreadZeroFill:
+    case typeThreadData:
+    case typeConstant:
+      if ((_sectionName == ".text") || (_sectionName == ".data") ||
+          (_sectionName == ".bss") || (_sectionName == ".rodata") ||
+          (_sectionName == ".tdata") || (_sectionName == ".tbss"))
+        return sectionBasedOnContent;
+    default:
+      break;
+    }
     return sectionCustomRequired;
   }
 
diff --git a/lld/lib/ReaderWriter/ELF/DefaultLayout.h b/lld/lib/ReaderWriter/ELF/DefaultLayout.h
index e8255c8c22d..c473d64dbcc 100644
--- a/lld/lib/ReaderWriter/ELF/DefaultLayout.h
+++ b/lld/lib/ReaderWriter/ELF/DefaultLayout.h
@@ -172,8 +172,7 @@ public:
                                        int32_t contentPermissions);
 
   /// \brief This maps the input sections to the output section names
-  virtual StringRef getSectionName(StringRef name, const int32_t contentType,
-                                   const int32_t contentPermissions);
+  virtual StringRef getSectionName(const DefinedAtom *da) const;
 
   /// \brief Gets or creates a section.
   AtomSection<ELFT> *getSection(
@@ -372,29 +371,35 @@ Layout::SectionOrder DefaultLayout<ELFT>::getSectionOrder(
 
 /// \brief This maps the input sections to the output section names
 template <class ELFT>
-StringRef DefaultLayout<ELFT>::getSectionName(
-    StringRef name, const int32_t contentType,
-    const int32_t contentPermissions) {
-  if ((contentType == DefinedAtom::typeZeroFill) ||
-      (contentType == DefinedAtom::typeZeroFillFast))
-    return ".bss";
-  if (name.startswith(".text"))
-    return ".text";
-  if (name.startswith(".rodata"))
-    return ".rodata";
-  if (name.startswith(".gcc_except_table"))
-    return ".gcc_except_table";
-  if (name.startswith(".data.rel.ro"))
-    return ".data.rel.ro";
-  if (name.startswith(".data.rel.local"))
-    return ".data.rel.local";
-  if (name.startswith(".data"))
-    return ".data";
-  if (name.startswith(".tdata"))
-    return ".tdata";
-  if (name.startswith(".tbss"))
-    return ".tbss";
-  return name;
+StringRef DefaultLayout<ELFT>::getSectionName(const DefinedAtom *da) const {
+  if (da->sectionChoice() == DefinedAtom::sectionBasedOnContent) {
+    switch (da->contentType()) {
+    case DefinedAtom::typeCode:
+      return ".text";
+    case DefinedAtom::typeData:
+      return ".data";
+    case DefinedAtom::typeConstant:
+      return ".rodata";
+    case DefinedAtom::typeZeroFill:
+      return ".bss";
+    case DefinedAtom::typeThreadData:
+      return ".tdata";
+    case DefinedAtom::typeThreadZeroFill:
+      return ".tbss";
+    default:
+      break;
+    }
+  }
+  return llvm::StringSwitch<StringRef>(da->customSectionName())
+      .StartsWith(".text", ".text")
+      .StartsWith(".rodata", ".rodata")
+      .StartsWith(".gcc_except_table", ".gcc_except_table")
+      .StartsWith(".data.rel.ro", ".data.rel.ro")
+      .StartsWith(".data.rel.local", ".data.rel.local")
+      .StartsWith(".data", ".data")
+      .StartsWith(".tdata", ".tdata")
+      .StartsWith(".tbss", ".tbss")
+      .Default(da->customSectionName());
 }
 
 /// \brief Gets the segment for a output section
@@ -519,12 +524,11 @@ ErrorOr<const lld::AtomLayout &> DefaultLayout<ELFT>::addAtom(const Atom *atom)
     // -noinhibit-exec.
     if (definedAtom->contentType() == DefinedAtom::typeUnknown)
       return make_error_code(llvm::errc::invalid_argument);
-    StringRef sectionName = definedAtom->customSectionName();
     const DefinedAtom::ContentPermissions permissions =
         definedAtom->permissions();
     const DefinedAtom::ContentType contentType = definedAtom->contentType();
 
-    sectionName = getSectionName(sectionName, contentType, permissions);
+    StringRef sectionName = getSectionName(definedAtom);
     AtomSection<ELFT> *section =
         getSection(sectionName, contentType, permissions);
     // Add runtime relocations to the .rela section.
diff --git a/lld/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h b/lld/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h
index d8c325d0d86..9797bf48398 100644
--- a/lld/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h
+++ b/lld/lib/ReaderWriter/ELF/Hexagon/HexagonTargetHandler.h
@@ -103,13 +103,15 @@ public:
   }
 
   /// \brief This maps the input sections to the output section names
-  virtual StringRef getSectionName(StringRef name, const int32_t contentType,
-                                   const int32_t contentPermissions) {
-    if ((contentType == DefinedAtom::typeDataFast) ||
-       (contentType == DefinedAtom::typeZeroFillFast))
+  virtual StringRef getSectionName(const DefinedAtom *da) const {
+    switch (da->contentType()) {
+    case DefinedAtom::typeDataFast:
+    case DefinedAtom::typeZeroFillFast:
       return ".sdata";
-    return DefaultLayout<HexagonELFType>::getSectionName(name, contentType,
-                                                         contentPermissions);
+    default:
+      break;
+    }
+    return DefaultLayout<HexagonELFType>::getSectionName(da);
   }
 
   /// \brief Gets or creates a section.
diff --git a/lld/test/elf/X86_64/sectionchoice.test b/lld/test/elf/X86_64/sectionchoice.test
new file mode 100644
index 00000000000..7b6c9a23e50
--- /dev/null
+++ b/lld/test/elf/X86_64/sectionchoice.test
@@ -0,0 +1,7 @@
+# This tests that we are able to properly set the sectionChoice for DefinedAtoms
+RUN: lld -flavor gnu -target x86_64-linux %p/Inputs/zerosizedsection.o  \
+RUN: --noinhibit-exec -o %t -emit-yaml
+RUN: FileCheck %s < %t
+
+CHECK-NOT: section-choice: sectionCustomRequired
+
diff --git a/lld/test/elf/mergeconstants.test b/lld/test/elf/mergeconstants.test
index abe132fc13b..08d41073e60 100644
--- a/lld/test/elf/mergeconstants.test
+++ b/lld/test/elf/mergeconstants.test
@@ -12,8 +12,6 @@ mergeAtoms:    scope:           global
 mergeAtoms:    type:            data
 mergeAtoms:    content:         [ 00, 00, 00, 00, 00, 00, 00, 00 ]
 mergeAtoms:    alignment:       2^3
-mergeAtoms:    section-choice:  custom-required
-mergeAtoms:    section-name:    .data
 mergeAtoms:    references:      
 mergeAtoms:      - kind:            R_X86_64_64
 mergeAtoms:        offset:          3