[PATCH] D35910: Make __start_sec __end_sec handling more precise

[Rafael Ávila de Espíndola via Phabricator via llvm-commits]

rafael updated this revision to Diff 108378.
rafael added a comment.

Address review comments


https://reviews.llvm.org/D35910

Files:
  ELF/LTO.cpp
  ELF/LTO.h
  test/ELF/lto/section-name.ll


Index: test/ELF/lto/section-name.ll
===================================================================
--- test/ELF/lto/section-name.ll
+++ test/ELF/lto/section-name.ll
@@ -7,5 +7,21 @@
 target triple = "x86_64-unknown-linux-gnu"
 
 @foo = hidden global i32 42, section "foo_section"
+ at bar = hidden global i32 42, section "bar_section"
+ at zed = hidden global i32 42, section "zed_section"
 
-; CHECK: foo_section PROGBITS
+ at __start_foo_section = external global i32
+ at __stop_bar_section = external global i32
+
+define i32* @use1() {
+  ret i32* @__start_foo_section
+}
+
+define i32* @use2() {
+  ret i32* @__stop_bar_section
+}
+
+; CHECK-NOT: zed_section
+; CHECK:     foo_section PROGBITS
+; CHECK-NEXT:     bar_section PROGBITS
+; CHECK-NOT: zed_section
Index: ELF/LTO.h
===================================================================
--- ELF/LTO.h
+++ ELF/LTO.h
@@ -22,6 +22,7 @@
 #define LLD_ELF_LTO_H
 
 #include "lld/Core/LLVM.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallString.h"
 #include <memory>
 #include <vector>
@@ -39,6 +40,8 @@
 class InputFile;
 
 class BitcodeCompiler {
+  llvm::DenseSet<StringRef> UsedStartStop;
+
 public:
   BitcodeCompiler();
   ~BitcodeCompiler();
Index: ELF/LTO.cpp
===================================================================
--- ELF/LTO.cpp
+++ ELF/LTO.cpp
@@ -11,6 +11,7 @@
 #include "Config.h"
 #include "Error.h"
 #include "InputFiles.h"
+#include "SymbolTable.h"
 #include "Symbols.h"
 #include "lld/Core/TargetOptionsCommandFlags.h"
 #include "llvm/ADT/STLExtras.h"
@@ -107,7 +108,14 @@
                                      Config->LTOPartitions);
 }
 
-BitcodeCompiler::BitcodeCompiler() : LTOObj(createLTO()) {}
+BitcodeCompiler::BitcodeCompiler() : LTOObj(createLTO()) {
+  for (Symbol *Sym : Symtab->getSymbols()) {
+    StringRef Name = Sym->body()->getName();
+    for (StringRef Prefix : {"__start_", "__stop_"})
+      if (Name.startswith(Prefix))
+        UsedStartStop.insert(Name.substr(Prefix.size()));
+  }
+}
 
 BitcodeCompiler::~BitcodeCompiler() = default;
 
@@ -138,7 +146,7 @@
 
     R.VisibleToRegularObj = Sym->IsUsedInRegularObj ||
                             (R.Prevailing && Sym->includeInDynsym()) ||
-                            isValidCIdentifier(ObjSym.getSectionName());
+                            UsedStartStop.count(ObjSym.getSectionName());
     if (R.Prevailing)
       undefine(Sym);
     R.LinkerRedefined = Config->RenamedSymbols.count(Sym);


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