Faster stack-protector for Android/AArch64.

Bionic has a defined thread-local location for the stack protector
cookie. Emit a direct load instead of going through __stack_chk_guard.

llvm-svn: 265481

1 files changed, 12 insertions, 16 deletions

diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
index db3fef524b3..23ae672944d 100644
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/lib/CodeGen/StackProtector.cpp
@@ -333,24 +333,20 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI,
                            AllocaInst *&AI, Value *&StackGuardVar) {
   bool SupportsSelectionDAGSP = false;
   PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext());
-  unsigned AddressSpace, Offset;
-  if (TLI->getStackCookieLocation(AddressSpace, Offset)) {
-    Constant *OffsetVal =
-        ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset);
-
-    StackGuardVar =
-        ConstantExpr::getIntToPtr(OffsetVal, PointerType::get(PtrTy,
-                                                              AddressSpace));
-  } else if (TT.isOSOpenBSD()) {
-    StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy);
-    cast<GlobalValue>(StackGuardVar)
-        ->setVisibility(GlobalValue::HiddenVisibility);
-  } else {
-    SupportsSelectionDAGSP = true;
-    StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
+  IRBuilder<> B(&F->getEntryBlock().front());
+
+  StackGuardVar = TLI->getStackCookieLocation(B);
+  if (!StackGuardVar) {
+    if (TT.isOSOpenBSD()) {
+      StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy);
+      cast<GlobalValue>(StackGuardVar)
+          ->setVisibility(GlobalValue::HiddenVisibility);
+    } else {
+      SupportsSelectionDAGSP = true;
+      StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
+    }
   }
 
-  IRBuilder<> B(&F->getEntryBlock().front());
   AI = B.CreateAlloca(PtrTy, nullptr, "StackGuardSlot");
   LoadInst *LI = B.CreateLoad(StackGuardVar, "StackGuard");
   B.CreateCall(Intrinsic::getDeclaration(M, Intrinsic::stackprotector),