Change the linkage of these global values to 'internal'.

The globals being generated here were given the 'private' linkage type. However,
this caused them to end up in different sections with the wrong prefix. E.g.,
they would be in the __TEXT,__const section with an 'L' prefix instead of an 'l'
(lowercase ell) prefix.

The problem is that the linker will eat a literal label with 'L'. If a weak
symbol is then placed into the __TEXT,__const section near that literal, then it
cannot distinguish between the literal and the weak symbol.

Part of the problems here was introduced because the address sanitizer converted
some C strings into constant initializers with trailing nuls. (Thus putting them
in the __const section with the wrong prefix.) The others were variables that
the address sanitizer created but simply had the wrong linkage type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187827 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index a954fa2d6eaa6b5ff6ce5f9cc0fc9ab64725251b..d77e20bf008d271526579ca39fa82e24dcfe9a63 100644 (file)
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -547,11 +547,11 @@ static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
   return Res;
 }
 
-// Create a constant for Str so that we can pass it to the run-time lib.
+// \brief Create a constant for Str so that we can pass it to the run-time lib.
 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
   Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
   GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
-                            GlobalValue::PrivateLinkage, StrConst,
+                            GlobalValue::InternalLinkage, StrConst,
                             kAsanGenPrefix);
   GV->setUnnamedAddr(true);  // Ok to merge these.
   GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
@@ -961,8 +961,11 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
     GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
 
     // Create a new global variable with enough space for a redzone.
+    GlobalValue::LinkageTypes Linkage = G->getLinkage();
+    if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
+      Linkage = GlobalValue::InternalLinkage;
     GlobalVariable *NewGlobal = new GlobalVariable(
-        M, NewTy, G->isConstant(), G->getLinkage(),
+        M, NewTy, G->isConstant(), Linkage,
         NewInitializer, "", G, G->getThreadLocalMode());
     NewGlobal->copyAttributesFrom(G);
     NewGlobal->setAlignment(MinRZ);
@@ -995,7 +998,7 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
 
   ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
   GlobalVariable *AllGlobals = new GlobalVariable(
-      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
+      M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
       ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
 
   // Create calls for poisoning before initializers run and unpoisoning after.

diff --git a/test/Instrumentation/AddressSanitizer/do-not-instrument-internal-globals.ll b/test/Instrumentation/AddressSanitizer/do-not-instrument-internal-globals.ll
index 0928c494154ef44918a03810546f2496487f4e75..d4fd93c164778b61723cc8fc87ae54a0495e8ea1 100644 (file)
--- a/test/Instrumentation/AddressSanitizer/do-not-instrument-internal-globals.ll
+++ b/test/Instrumentation/AddressSanitizer/do-not-instrument-internal-globals.ll
@@ -16,5 +16,5 @@ declare void @_Z3fooPi(i32*)
 ; We create one global string constant for the stack frame above.
 ; It should have unnamed_addr and align 1.
 ; Make sure we don't create any other global constants.
-; CHECK: = private unnamed_addr constant{{.*}}align 1
-; CHECK-NOT: = private unnamed_addr constant
+; CHECK: = internal unnamed_addr constant{{.*}}align 1
+; CHECK-NOT: = internal unnamed_addr constant