[PATCH] D56089: [ELF] A shared object is needed if any of its occurrences is needed

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 179568.
MaskRay added a comment.

Spell out the two components of the try_emplace return value


Repository:
  rLLD LLVM Linker

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56089/new/

https://reviews.llvm.org/D56089

Files:
  ELF/SymbolTable.cpp
  ELF/SymbolTable.h
  test/ELF/as-needed-not-in-regular.s


Index: test/ELF/as-needed-not-in-regular.s
===================================================================
--- test/ELF/as-needed-not-in-regular.s
+++ test/ELF/as-needed-not-in-regular.s
@@ -19,6 +19,12 @@
 # the reference to a2 is weak, don't add a DT_NEEDED entry for a.so.
 # CHECK-NOT: a.so
 
+# RUN: ld.lld %t.o %tb.so --as-needed %ta.so --no-as-needed %ta.so -o %t
+# RUN: llvm-readelf -d %t | FileCheck %s -check-prefix=NEEDED
+
+# a.so is needed because one of its occurrences is needed.
+# NEEDED: a.so
+
 .global _start
 .weak a2
 _start:
Index: ELF/SymbolTable.h
===================================================================
--- ELF/SymbolTable.h
+++ ELF/SymbolTable.h
@@ -108,7 +108,7 @@
   llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
 
   // Set of .so files to not link the same shared object file more than once.
-  llvm::DenseSet<StringRef> SoNames;
+  llvm::DenseMap<StringRef, InputFile *> SoNames;
 
   // A map from demangled symbol names to their symbol objects.
   // This mapping is 1:N because two symbols with different versions
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -93,8 +93,17 @@
   // .so file
   if (auto *F = dyn_cast<SharedFile<ELFT>>(File)) {
     // DSOs are uniquified not by filename but by soname.
+    // If a DSO appears more than once on the command line with and without
+    // --as-needed, --no-as-needed takes precedence over --as-needed because
+    // a user is likely to add an extra DSO with --no-as-needed to force
+    // it to be added to the dependency list.
     F->parseSoName();
-    if (errorCount() || !SoNames.insert(F->SoName).second)
+    DenseMap<StringRef, InputFile *>::iterator It;
+    bool WasInserted;
+    std::tie(It, WasInserted) = SoNames.try_emplace(F->SoName, F);
+    cast<SharedFile<ELFT>>(It->second)->IsNeeded |= F->IsNeeded;
+
+    if (errorCount() || !WasInserted)
       return;
     SharedFiles.push_back(F);
     F->parseRest();


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