[PATCH] D158910: [BOLT] Local hidden should be global syms

[Rafael Auler via Phabricator via llvm-commits]

rafauler created this revision.
rafauler added a reviewer: bolt.
Herald added subscribers: treapster, ayermolo.
Herald added a reviewer: Amir.
Herald added a reviewer: maksfb.
Herald added a project: All.
rafauler requested review of this revision.
Herald added subscribers: llvm-commits, yota9.
Herald added a project: LLVM.

Register all hidden local symbols as globals, since they are
still unique in the context of the input binary BOLT is
processing. This is used to fetch a single definition of
_GLOBAL_OFFSET_TABLE_.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158910

Files:
  bolt/lib/Rewrite/RewriteInstance.cpp
  bolt/test/AArch64/array_end.c


Index: bolt/test/AArch64/array_end.c
===================================================================
--- bolt/test/AArch64/array_end.c
+++ bolt/test/AArch64/array_end.c
@@ -8,7 +8,7 @@
 // RUN: llvm-bolt %t.exe -o %t.bolt --print-disasm \
 // RUN:  --print-only="callFini" | FileCheck %s
 
-// CHECK: adr [[REG:x[0-28]+]], "__fini_array_end/1"
+// CHECK: adr [[REG:x[0-28]+]], __fini_array_end
 
 __attribute__((destructor)) void destr() {}
 
Index: bolt/lib/Rewrite/RewriteInstance.cpp
===================================================================
--- bolt/lib/Rewrite/RewriteInstance.cpp
+++ bolt/lib/Rewrite/RewriteInstance.cpp
@@ -766,6 +766,15 @@
     }
   };
   std::unordered_map<SymbolRef, StringRef, SymbolRefHash> SymbolToFileName;
+  auto isSymbolGlobal = [](const ELFSymbolRef &Sym) {
+    if (cantFail(Sym.getFlags()) & SymbolRef::SF_Global)
+      return true;
+    // Hidden symbols are globals that were demoted to local at link-time.
+    // They should still be unique names at DSO-level.
+    if (cantFail(Sym.getFlags()) & SymbolRef::SF_Hidden)
+      return true;
+    return false;
+  };
   for (const ELFSymbolRef &Symbol : InputFile->symbols()) {
     Expected<StringRef> NameOrError = Symbol.getName();
     if (NameOrError && NameOrError->startswith("__asan_init")) {
@@ -793,8 +802,7 @@
       SeenFileName = true;
       continue;
     }
-    if (!FileSymbolName.empty() &&
-        !(cantFail(Symbol.getFlags()) & SymbolRef::SF_Global))
+    if (!FileSymbolName.empty() && !(isSymbolGlobal(Symbol)))
       SymbolToFileName[Symbol] = FileSymbolName;
   }
 
@@ -951,7 +959,7 @@
     std::string AlternativeName;
     if (Name.empty()) {
       UniqueName = "ANONYMOUS." + std::to_string(AnonymousId++);
-    } else if (cantFail(Symbol.getFlags()) & SymbolRef::SF_Global) {
+    } else if (isSymbolGlobal(Symbol)) {
       if (const BinaryData *BD = BC->getBinaryDataByName(Name)) {
         if (BD->getSize() == ELFSymbolRef(Symbol).getSize() &&
             BD->getAddress() == Address) {


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