Add sanitizer-specific GlobalValue attributes.

Plan is the migrate the global variable metadata for sanitizers, that's
currently carried around generally in the 'llvm.asan.globals' section,
onto the global variable itself.

This patch adds the attribute and plumbs it through the LLVM IR and
bitcode formats, but is a no-op other than that so far.

Reviewed By: vitalybuka, kstoimenov

Differential Revision: https://reviews.llvm.org/D126100

1 files changed, 15 insertions, 2 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 4e1729f..691b332 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1223,6 +1223,14 @@ static StringEncoding getStringEncoding(StringRef Str) {
   return SE_Fixed7;
 }
 
+static_assert(sizeof(GlobalValue::SanitizerMetadata) <= sizeof(unsigned),
+              "Sanitizer Metadata is too large for naive serialization.");
+static unsigned
+serializeSanitizerMetadata(const GlobalValue::SanitizerMetadata &Meta) {
+  return Meta.NoAddress | (Meta.NoHWAddress << 1) |
+         (Meta.NoMemtag << 2) | (Meta.IsDynInit << 3);
+}
+
 /// Emit top-level description of module, including target triple, inline asm,
 /// descriptors for global variables, and function prototype info.
 /// Returns the bit offset to backpatch with the location of the real VST.
@@ -1346,7 +1354,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
     //             linkage, alignment, section, visibility, threadlocal,
     //             unnamed_addr, externally_initialized, dllstorageclass,
-    //             comdat, attributes, DSO_Local]
+    //             comdat, attributes, DSO_Local, GlobalSanitizer]
     Vals.push_back(addToStrtab(GV.getName()));
     Vals.push_back(GV.getName().size());
     Vals.push_back(VE.getTypeID(GV.getValueType()));
@@ -1363,7 +1371,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
         GV.isExternallyInitialized() ||
         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
         GV.hasComdat() || GV.hasAttributes() || GV.isDSOLocal() ||
-        GV.hasPartition()) {
+        GV.hasPartition() || GV.hasSanitizerMetadata()) {
       Vals.push_back(getEncodedVisibility(GV));
       Vals.push_back(getEncodedThreadLocalMode(GV));
       Vals.push_back(getEncodedUnnamedAddr(GV));
@@ -1377,6 +1385,11 @@ void ModuleBitcodeWriter::writeModuleInfo() {
       Vals.push_back(GV.isDSOLocal());
       Vals.push_back(addToStrtab(GV.getPartition()));
       Vals.push_back(GV.getPartition().size());
+
+      if (GV.hasSanitizerMetadata())
+        Vals.push_back(serializeSanitizerMetadata(GV.getSanitizerMetadata()));
+      else
+        Vals.push_back(UINT_MAX);
     } else {
       AbbrevToUse = SimpleGVarAbbrev;
     }