[safestack] Use non-thread-local unsafe stack pointer for Contiki OS

Patch by Michael LeMay

Differential revision: http://reviews.llvm.org/D19852

llvm-svn: 284254

1 files changed, 1 insertions, 49 deletions

diff --git a/llvm/lib/CodeGen/SafeStack.cpp b/llvm/lib/CodeGen/SafeStack.cpp
index ed3fa8cd6ad..43f7b301a08 100644
--- a/llvm/lib/CodeGen/SafeStack.cpp
+++ b/llvm/lib/CodeGen/SafeStack.cpp
@@ -52,16 +52,6 @@ using namespace llvm::safestack;
 
 #define DEBUG_TYPE "safestack"
 
-enum UnsafeStackPtrStorageVal { ThreadLocalUSP, SingleThreadUSP };
-
-static cl::opt<UnsafeStackPtrStorageVal> USPStorage("safe-stack-usp-storage",
-    cl::Hidden, cl::init(ThreadLocalUSP),
-    cl::desc("Type of storage for the unsafe stack pointer"),
-    cl::values(clEnumValN(ThreadLocalUSP, "thread-local",
-                          "Thread-local storage"),
-               clEnumValN(SingleThreadUSP, "single-thread",
-                          "Non-thread-local storage")));
-
 namespace llvm {
 
 STATISTIC(NumFunctions, "Total number of functions");
@@ -123,9 +113,6 @@ class SafeStack : public FunctionPass {
   /// might expect to appear on the stack on most common targets.
   enum { StackAlignment = 16 };
 
-  /// \brief Build a value representing a pointer to the unsafe stack pointer.
-  Value *getOrCreateUnsafeStackPtr(IRBuilder<> &IRB, Function &F);
-
   /// \brief Return the value of the stack canary.
   Value *getStackGuard(IRBuilder<> &IRB, Function &F);
 
@@ -355,41 +342,6 @@ bool SafeStack::IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize) {
   return true;
 }
 
-Value *SafeStack::getOrCreateUnsafeStackPtr(IRBuilder<> &IRB, Function &F) {
-  // Check if there is a target-specific location for the unsafe stack pointer.
-  if (Value *V = TL->getSafeStackPointerLocation(IRB))
-    return V;
-
-  // Otherwise, assume the target links with compiler-rt, which provides a
-  // thread-local variable with a magic name.
-  Module &M = *F.getParent();
-  const char *UnsafeStackPtrVar = "__safestack_unsafe_stack_ptr";
-  auto UnsafeStackPtr =
-      dyn_cast_or_null<GlobalVariable>(M.getNamedValue(UnsafeStackPtrVar));
-
-  bool UseTLS = USPStorage == ThreadLocalUSP;
-
-  if (!UnsafeStackPtr) {
-    auto TLSModel = UseTLS ?
-        GlobalValue::InitialExecTLSModel :
-        GlobalValue::NotThreadLocal;
-    // The global variable is not defined yet, define it ourselves.
-    // We use the initial-exec TLS model because we do not support the
-    // variable living anywhere other than in the main executable.
-    UnsafeStackPtr = new GlobalVariable(
-        M, StackPtrTy, false, GlobalValue::ExternalLinkage, nullptr,
-        UnsafeStackPtrVar, nullptr, TLSModel);
-  } else {
-    // The variable exists, check its type and attributes.
-    if (UnsafeStackPtr->getValueType() != StackPtrTy)
-      report_fatal_error(Twine(UnsafeStackPtrVar) + " must have void* type");
-    if (UseTLS != UnsafeStackPtr->isThreadLocal())
-      report_fatal_error(Twine(UnsafeStackPtrVar) + " must " +
-                         (UseTLS ? "" : "not ") + "be thread-local");
-  }
-  return UnsafeStackPtr;
-}
-
 Value *SafeStack::getStackGuard(IRBuilder<> &IRB, Function &F) {
   Value *StackGuardVar = TL->getIRStackGuard(IRB);
   if (!StackGuardVar)
@@ -784,7 +736,7 @@ bool SafeStack::runOnFunction(Function &F) {
     ++NumUnsafeStackRestorePointsFunctions;
 
   IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
-  UnsafeStackPtr = getOrCreateUnsafeStackPtr(IRB, F);
+  UnsafeStackPtr = TL->getSafeStackPointerLocation(IRB);
 
   // Load the current stack pointer (we'll also use it as a base pointer).
   // FIXME: use a dedicated register for it ?