From c9d82b9e16d0f4c81aefd0cbcdfa476ac2c17634 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Thu, 27 Apr 2017 04:01:36 +0000
Subject: [PATCH] Simplify BinaryFile::parse and add comments.

llvm-svn: 301514
---
 lld/ELF/InputFiles.cpp | 37 ++++++++++++++++++-------------------
 lld/ELF/Strings.h      |  4 ++++
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index b032dc8f4334..f6ec4dd23f6f 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -883,30 +883,29 @@ static ELFKind getELFKind(MemoryBufferRef MB) {
 }
 
 template <class ELFT> void BinaryFile::parse() {
-  StringRef Buf = MB.getBuffer();
-  ArrayRef<uint8_t> Data =
-      makeArrayRef<uint8_t>((const uint8_t *)Buf.data(), Buf.size());
-
-  std::string Filename = MB.getBufferIdentifier();
-  std::transform(Filename.begin(), Filename.end(), Filename.begin(),
-                 [](char C) { return isalnum(C) ? C : '_'; });
-  Filename = "_binary_" + Filename;
-  StringRef StartName = Saver.save(Filename + "_start");
-  StringRef EndName = Saver.save(Filename + "_end");
-  StringRef SizeName = Saver.save(Filename + "_size");
-
+  ArrayRef<uint8_t> Data = toArrayRef(MB.getBuffer());
   auto *Section =
       make<InputSection>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, 8, Data, ".data");
   Sections.push_back(Section);
 
-  elf::Symtab<ELFT>::X->addRegular(StartName, STV_DEFAULT, STT_OBJECT, 0, 0,
-                                   STB_GLOBAL, Section, nullptr);
-  elf::Symtab<ELFT>::X->addRegular(EndName, STV_DEFAULT, STT_OBJECT,
-                                   Data.size(), 0, STB_GLOBAL, Section,
-                                   nullptr);
-  elf::Symtab<ELFT>::X->addRegular(SizeName, STV_DEFAULT, STT_OBJECT,
-                                   Data.size(), 0, STB_GLOBAL, nullptr,
+  // For each input file foo that is embedded to a result as a binary
+  // blob, we define _binary_foo_{start,end,size} symbols, so that
+  // user programs can access blobs by name. Non-alphanumeric
+  // characters in a filename are replaced with underscore.
+  std::string S = "_binary_" + MB.getBufferIdentifier().str();
+  for (size_t I = 0; I < S.size(); ++I)
+    if (!isalnum(S[I]))
+      S[I] = '_';
+
+  elf::Symtab<ELFT>::X->addRegular(Saver.save(S + "_start"), STV_DEFAULT,
+                                   STT_OBJECT, 0, 0, STB_GLOBAL, Section,
                                    nullptr);
+  elf::Symtab<ELFT>::X->addRegular(Saver.save(S + "_end"), STV_DEFAULT,
+                                   STT_OBJECT, Data.size(), 0, STB_GLOBAL,
+                                   Section, nullptr);
+  elf::Symtab<ELFT>::X->addRegular(Saver.save(S + "_size"), STV_DEFAULT,
+                                   STT_OBJECT, Data.size(), 0, STB_GLOBAL,
+                                   nullptr, nullptr);
 }
 
 static bool isBitcode(MemoryBufferRef MB) {
diff --git a/lld/ELF/Strings.h b/lld/ELF/Strings.h
index 934b6427105f..bcfa28144989 100644
--- a/lld/ELF/Strings.h
+++ b/lld/ELF/Strings.h
@@ -76,6 +76,10 @@ llvm::Optional<std::string> demangle(StringRef Name);
 inline StringRef toStringRef(ArrayRef<uint8_t> Arr) {
   return {(const char *)Arr.data(), Arr.size()};
 }
+
+inline ArrayRef<uint8_t> toArrayRef(StringRef S) {
+  return {(const uint8_t *)S.data(), S.size()};
+}
 }
 }