[llvm] 8133e28 - Add ASan metadata globals to @llvm.compiler.used under COFF

[Arthur Eubanks via llvm-commits]

Author: Arthur Eubanks
Date: 2020-06-05T09:04:52-07:00
New Revision: 8133e289b6f697cb5d102d7f78223b64098808b5

URL: https://github.com/llvm/llvm-project/commit/8133e289b6f697cb5d102d7f78223b64098808b5
DIFF: https://github.com/llvm/llvm-project/commit/8133e289b6f697cb5d102d7f78223b64098808b5.diff

LOG: Add ASan metadata globals to @llvm.compiler.used under COFF

Summary:
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.

Reviewers: vitalybuka, hans

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81175

Added: 
    

Modified: 
    llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
    llvm/test/Instrumentation/AddressSanitizer/global_metadata_windows.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 55f58a6e5477..9c039f0cfcc7 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2036,11 +2036,15 @@ void ModuleAddressSanitizer::InstrumentGlobalsCOFF(
   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 @@ void ModuleAddressSanitizer::InstrumentGlobalsCOFF(
 
     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(

diff  --git a/llvm/test/Instrumentation/AddressSanitizer/global_metadata_windows.ll b/llvm/test/Instrumentation/AddressSanitizer/global_metadata_windows.ll
index 937f777f28e7..744366e4c376 100644
--- a/llvm/test/Instrumentation/AddressSanitizer/global_metadata_windows.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/global_metadata_windows.ll
@@ -17,8 +17,10 @@ $mystr = comdat any
 ; CHECK: @dead_global = global { i32, [60 x i8] } { i32 42, [60 x i8] zeroinitializer }, comdat, align 32
 ; CHECK: @private_str = internal constant { [8 x i8], [56 x i8] } { [8 x i8] c"private\00", [56 x i8] zeroinitializer }, comdat, align 32
 
-; CHECK: @__asan_global_dead_global = private global { {{.*}} }, section ".ASAN$GL", comdat($dead_global), align 64
-; CHECK: @__asan_global_private_str = private global { {{.*}} }, section ".ASAN$GL", comdat($private_str), align 64
+; CHECK: @__asan_global_dead_global = private global { {{.*}} }, section ".ASAN$GL", comdat($dead_global), align 64, !associated
+; CHECK: @__asan_global_private_str = private global { {{.*}} }, section ".ASAN$GL", comdat($private_str), align 64, !associated
+
+; CHECK: @llvm.compiler.used {{.*}} @__asan_global_dead_global {{.*}} @__asan_global_private_str {{.*}} section "llvm.metadata"
 
 @dead_global = local_unnamed_addr global i32 42, align 4
 @mystr = linkonce_odr unnamed_addr constant [5 x i8] c"main\00", comdat, align 1