[PATCH] D81175: Add ASan metadata globals to @llvm.compiler.used under COFF

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
aeubanks added reviewers: vitalybuka, hans.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.
aeubanks added a comment.

As for tests, I think making these work under the NPM, which we hopefully switch to soon, counts as tests.


This matches ELF.

This makes the number of ASan failures under the new pass manager on
Windows go from 18 to 1.

Under the old pass manager, the ASan module pass was one of the very
last things run, so these globals didn't get removed due to GlobalOpt.
But with the NPM the ASan module pass that adds these globals are run
much earlier in the pipeline and GlobalOpt ends up removing them.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81175

Files:
  llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp


Index: llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2036,11 +2036,15 @@
   assert(ExtendedGlobals.size() == MetadataInitializers.size());
   auto &DL = M.getDataLayout();
 
+  SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
   for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
     Constant *Initializer = MetadataInitializers[i];
     GlobalVariable *G = ExtendedGlobals[i];
     GlobalVariable *Metadata =
         CreateMetadataGlobal(M, Initializer, G->getName());
+    MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
+    Metadata->setMetadata(LLVMContext::MD_associated, MD);
+    MetadataGlobals[i] = Metadata;
 
     // The MSVC linker always inserts padding when linking incrementally. We
     // cope with that by aligning each struct to its size, which must be a power
@@ -2052,6 +2056,11 @@
 
     SetComdatForGlobalMetadata(G, Metadata, "");
   }
+
+  // Update llvm.compiler.used, adding the new metadata globals. This is
+  // needed so that during LTO these variables stay alive.
+  if (!MetadataGlobals.empty())
+    appendToCompilerUsed(M, MetadataGlobals);
 }
 
 void ModuleAddressSanitizer::InstrumentGlobalsELF(


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D81175.268514.patch
Type: text/x-patch
Size: 1386 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200604/1b26ac83/attachment.bin>