[PATCH] D130073: [BOLT] Handle broken .dynsym in stripped binaries

[Huan Nguyen via Phabricator via llvm-commits]

nhuhuan created this revision.
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Strip tools cause a few symbols in .dynsym to have bad section index.
This update safely keeps such broken symbols intact.

Test Plan:

  ninja check-bolt


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130073

Files:
  bolt/lib/Rewrite/RewriteInstance.cpp


Index: bolt/lib/Rewrite/RewriteInstance.cpp
===================================================================
--- bolt/lib/Rewrite/RewriteInstance.cpp
+++ bolt/lib/Rewrite/RewriteInstance.cpp
@@ -4490,6 +4490,14 @@
   std::vector<ELFSymTy> Symbols;
 
   auto getNewSectionIndex = [&](uint32_t OldIndex) {
+    // For dynamic symbol table, the section index could be wrong on the input,
+    // and its value is ignored by the runtime if it's different from
+    // SHN_UNDEF and SHN_ABS.
+    // However, we still need to update dynamic symbol table, so return a
+    // section index, even though the index is broken.
+    if (IsDynSym && OldIndex >= NewSectionIndex.size())
+      return OldIndex;
+
     assert(OldIndex < NewSectionIndex.size() && "section index out of bounds");
     const uint32_t NewIndex = NewSectionIndex[OldIndex];
 


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