[ELF] Move InputSectionBase::file to SectionBase

... and add getCtx (file->ctx). This allows InputSectionBase and
OutputSection to access ctx without taking an extra function argument.

Author: MaskRay

lld/ELF/EhFrame.cpp

@@ -119,7 +119,7 @@ void EhReader::skipAugP() {
   uint8_t enc = readByte();
   if ((enc & 0xf0) == DW_EH_PE_aligned)
     failOn(d.data() - 1, "DW_EH_PE_aligned encoding is not supported");
-  size_t size = getAugPSize(ctx, enc);
+  size_t size = getAugPSize(isec->getCtx(), enc);
   if (size == 0)
     failOn(d.data() - 1, "unknown FDE encoding");
   if (size >= d.size())

lld/ELF/InputFiles.h

@@ -48,8 +48,10 @@ void parseFiles(Ctx &, const std::vector<InputFile *> &files);
 
 // The root class of input files.
 class InputFile {
-protected:
+public:
   Ctx &ctx;
+
+protected:
   std::unique_ptr<Symbol *[]> symbols;
   uint32_t numSymbols = 0;
   SmallVector<InputSectionBase *, 0> sections;

lld/ELF/InputSection.cpp

@@ -52,9 +52,9 @@ InputSectionBase::InputSectionBase(InputFile *file, uint64_t flags,
                                    uint32_t link, uint32_t info,
                                    uint32_t addralign, ArrayRef<uint8_t> data,
                                    StringRef name, Kind sectionKind)
-    : SectionBase(sectionKind, name, flags, entsize, addralign, type, info,
-                  link),
-      file(file), content_(data.data()), size(data.size()) {
+    : SectionBase(sectionKind, file, name, flags, entsize, addralign, type,
+                  info, link),
+      content_(data.data()), size(data.size()) {
   // In order to reduce memory allocation, we assume that mergeable
   // sections are smaller than 4 GiB, which is not an unreasonable
   // assumption as of 2017.
@@ -88,7 +88,7 @@ template <class ELFT>
 InputSectionBase::InputSectionBase(ObjFile<ELFT> &file,
                                    const typename ELFT::Shdr &hdr,
                                    StringRef name, Kind sectionKind)
-    : InputSectionBase(&file, getFlags(ctx, hdr.sh_flags), hdr.sh_type,
+    : InputSectionBase(&file, getFlags(file.ctx, hdr.sh_flags), hdr.sh_type,
                        hdr.sh_entsize, hdr.sh_link, hdr.sh_info,
                        hdr.sh_addralign, getSectionContents(file, hdr), name,
                        sectionKind) {
@@ -185,6 +185,8 @@ RelsOrRelas<ELFT> InputSectionBase::relsOrRelas(bool supportsCrel) const {
   return ret;
 }
 
+Ctx &SectionBase::getCtx() const { return file->ctx; }
+
 uint64_t SectionBase::getOffset(uint64_t offset) const {
   switch (kind()) {
   case Output: {

lld/ELF/InputSection.h

@@ -78,6 +78,12 @@ class SectionBase {
 
   uint8_t partition = 1;
   uint32_t type;
+
+  // The file which contains this section. For InputSectionBase, its dynamic
+  // type is usually ObjFile<ELFT>, but may be an InputFile of InternalKind
+  // (for a synthetic section).
+  InputFile *file;
+
   StringRef name;
 
   // The 1-indexed partition that this section is assigned to by the garbage
@@ -92,6 +98,7 @@ class SectionBase {
   uint32_t link;
   uint32_t info;
 
+  Ctx &getCtx() const;
   OutputSection *getOutputSection();
   const OutputSection *getOutputSection() const {
     return const_cast<SectionBase *>(this)->getOutputSection();
@@ -108,12 +115,12 @@ class SectionBase {
   void markDead() { partition = 0; }
 
 protected:
-  constexpr SectionBase(Kind sectionKind, StringRef name, uint64_t flags,
-                        uint32_t entsize, uint32_t addralign, uint32_t type,
-                        uint32_t info, uint32_t link)
+  constexpr SectionBase(Kind sectionKind, InputFile *file, StringRef name,
+                        uint64_t flags, uint32_t entsize, uint32_t addralign,
+                        uint32_t type, uint32_t info, uint32_t link)
       : sectionKind(sectionKind), bss(false), keepUnique(false), type(type),
-        name(name), flags(flags), addralign(addralign), entsize(entsize),
-        link(link), info(info) {}
+        file(file), name(name), flags(flags), addralign(addralign),
+        entsize(entsize), link(link), info(info) {}
 };
 
 struct SymbolAnchor {
@@ -150,11 +157,6 @@ class InputSectionBase : public SectionBase {
     return s->kind() != Output && s->kind() != Class;
   }
 
-  // The file which contains this section. Its dynamic type is usually
-  // ObjFile<ELFT>, but may be an InputFile of InternalKind (for a synthetic
-  // section).
-  InputFile *file;
-
   // Input sections are part of an output section. Special sections
   // like .eh_frame and merge sections are first combined into a
   // synthetic section that is then added to an output section. In all

lld/ELF/OutputSections.cpp

@@ -66,8 +66,9 @@ void OutputSection::writeHeaderTo(typename ELFT::Shdr *shdr) {
 }
 
 OutputSection::OutputSection(StringRef name, uint32_t type, uint64_t flags)
-    : SectionBase(Output, name, flags, /*Entsize*/ 0, /*Alignment*/ 1, type,
-                  /*Info*/ 0, /*Link*/ 0) {}
+    : SectionBase(Output, ctx.internalFile, name, flags, /*entsize=*/0,
+                  /*addralign=*/1, type,
+                  /*info=*/0, /*link=*/0) {}
 
 // We allow sections of types listed below to merged into a
 // single progbits section. This is typically done by linker

lld/ELF/OutputSections.h

@@ -150,7 +150,8 @@ struct SectionClass final : public SectionBase {
   SmallVector<InputSectionDescription *, 0> commands;
   bool assigned = false;
 
-  SectionClass(StringRef name) : SectionBase(Class, name, 0, 0, 0, 0, 0, 0) {}
+  SectionClass(StringRef name)
+      : SectionBase(Class, nullptr, name, 0, 0, 0, 0, 0, 0) {}
   static bool classof(const SectionBase *s) { return s->kind() == Class; }
 };