Added support for thread local variables on all Apple OS variants.

We had support that assumed that thread local data for a variable could be determined solely from the module in which the variable exists. While this work for linux, it doesn't work for Apple OSs. The DWARF for thread local variables consists of location opcodes that do something like:

DW_OP_const8u (x)
DW_OP_form_tls_address

or 

DW_OP_const8u (x)
DW_OP_GNU_push_tls_address

The "x" is allowed to be anything that is needed to determine the location of the variable. For Linux "x" is the offset within the TLS data for a given executable (ModuleSP in LLDB). For Apple OS variants, it is the file address of the data structure that contains a pthread key that can be used with pthread_getspecific() and the offset needed. 

This fix passes the "x" along to the thread:

virtual lldb::addr_t
lldb_private::Thread::GetThreadLocalData(const lldb::ModuleSP module, lldb::addr_t tls_file_addr);

Then this is passed along to the DynamicLoader::GetThreadLocalData():

virtual lldb::addr_t
lldb_private::DynamicLoader::GetThreadLocalData(const lldb::ModuleSP module, const lldb::ThreadSP thread, lldb::addr_t tls_file_addr);

This allows each DynamicLoader plug-in do the right thing for the current OS.

The DynamicLoaderMacOSXDYLD was modified to be able to grab the pthread key from the data structure that is in memory and call "void *pthread_getspecific(pthread_key_t key)" to get the value of the thread local storage and it caches it per thread since it never changes.

I had to update the test case to access the thread local data before trying to print it as on Apple OS variants, thread locals are not available unless they have been accessed at least one by the current thread.

I also added a new lldb::ValueType named "eValueTypeVariableThreadLocal" so that we can ask SBValue objects for their ValueType and be able to tell when we have a thread local variable.

<rdar://problem/23308080>

llvm-svn: 274366

1 files changed, 126 insertions, 6 deletions

diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index 610c8cf3a5f..b81d60e9b06 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1003,7 +1003,128 @@ DWARFExpression::Update_DW_OP_addr (lldb::addr_t file_addr)
 }
 
 bool
-DWARFExpression::LocationListContainsAddress (lldb::addr_t loclist_base_addr, lldb::addr_t addr) const
+DWARFExpression::ContainsThreadLocalStorage() const
+{
+    // We are assuming for now that any thread local variable will not
+    // have a location list. This has been true for all thread local
+    // variables we have seen so far produced by any compiler.
+    if (IsLocationList())
+        return false;
+    lldb::offset_t offset = 0;
+    while (m_data.ValidOffset(offset))
+    {
+        const uint8_t op = m_data.GetU8(&offset);
+
+        if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address)
+            return true;
+        const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
+        if (op_arg_size == LLDB_INVALID_OFFSET)
+            return false;
+        else
+            offset += op_arg_size;
+    }
+    return false;
+}
+bool
+DWARFExpression::LinkThreadLocalStorage(
+    lldb::ModuleSP new_module_sp, std::function<lldb::addr_t(lldb::addr_t file_addr)> const &link_address_callback)
+{
+    // We are assuming for now that any thread local variable will not
+    // have a location list. This has been true for all thread local
+    // variables we have seen so far produced by any compiler.
+    if (IsLocationList())
+        return false;
+
+    const uint32_t addr_byte_size = m_data.GetAddressByteSize();
+    // We have to make a copy of the data as we don't know if this
+    // data is from a read only memory mapped buffer, so we duplicate
+    // all of the data first, then modify it, and if all goes well,
+    // we then replace the data for this expression
+
+    // So first we copy the data into a heap buffer
+    std::shared_ptr<DataBufferHeap> heap_data_sp(new DataBufferHeap(m_data.GetDataStart(), m_data.GetByteSize()));
+
+    // Make en encoder so we can write the address into the buffer using
+    // the correct byte order (endianness)
+    DataEncoder encoder(heap_data_sp->GetBytes(), heap_data_sp->GetByteSize(), m_data.GetByteOrder(), addr_byte_size);
+
+    lldb::offset_t offset = 0;
+    lldb::offset_t const_offset = 0;
+    lldb::addr_t const_value = 0;
+    size_t const_byte_size = 0;
+    while (m_data.ValidOffset(offset))
+    {
+        const uint8_t op = m_data.GetU8(&offset);
+
+        bool decoded_data = false;
+        switch (op)
+        {
+            case DW_OP_const4u:
+                // Remember the const offset in case we later have a DW_OP_form_tls_address
+                // or DW_OP_GNU_push_tls_address
+                const_offset = offset;
+                const_value = m_data.GetU32(&offset);
+                decoded_data = true;
+                const_byte_size = 4;
+                break;
+
+            case DW_OP_const8u:
+                // Remember the const offset in case we later have a DW_OP_form_tls_address
+                // or DW_OP_GNU_push_tls_address
+                const_offset = offset;
+                const_value = m_data.GetU64(&offset);
+                decoded_data = true;
+                const_byte_size = 8;
+                break;
+
+            case DW_OP_form_tls_address:
+            case DW_OP_GNU_push_tls_address:
+                // DW_OP_form_tls_address and DW_OP_GNU_push_tls_address must be preceded by
+                // a file address on the stack. We assume that DW_OP_const4u or DW_OP_const8u
+                // is used for these values, and we check that the last opcode we got before
+                // either of these was DW_OP_const4u or DW_OP_const8u. If so, then we can link
+                // the value accodingly. For Darwin, the value in the DW_OP_const4u or
+                // DW_OP_const8u is the file address of a structure that contains a function
+                // pointer, the pthread key and the offset into the data pointed to by the
+                // pthread key. So we must link this address and also set the module of this
+                // expression to the new_module_sp so we can resolve the file address correctly
+                if (const_byte_size > 0)
+                {
+                    lldb::addr_t linked_file_addr = link_address_callback(const_value);
+                    if (linked_file_addr == LLDB_INVALID_ADDRESS)
+                        return false;
+                    // Replace the address in the new buffer
+                    if (encoder.PutMaxU64(const_offset, const_byte_size, linked_file_addr) == UINT32_MAX)
+                        return false;
+                }
+                break;
+
+            default:
+                const_offset = 0;
+                const_value = 0;
+                const_byte_size = 0;
+                break;
+        }
+
+        if (!decoded_data)
+        {
+            const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
+            if (op_arg_size == LLDB_INVALID_OFFSET)
+                return false;
+            else
+                offset += op_arg_size;
+        }
+    }
+
+    // If we linked the TLS address correctly, update the module so that when the expression
+    // is evaluated it can resolve the file address to a load address and read the TLS data
+    m_module_wp = new_module_sp;
+    m_data.SetData(heap_data_sp);
+    return true;
+}
+
+bool
+DWARFExpression::LocationListContainsAddress(lldb::addr_t loclist_base_addr, lldb::addr_t addr) const
 {
     if (addr == LLDB_INVALID_ADDRESS)
         return false;
@@ -2845,18 +2966,17 @@ DWARFExpression::Evaluate
                 }
 
                 // Lookup the TLS block address for this thread and module.
-                addr_t tls_addr = thread->GetThreadLocalData (module_sp);
+                const addr_t tls_file_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+                const addr_t tls_load_addr = thread->GetThreadLocalData(module_sp, tls_file_addr);
 
-                if (tls_addr == LLDB_INVALID_ADDRESS)
+                if (tls_load_addr == LLDB_INVALID_ADDRESS)
                 {
                     if (error_ptr)
                         error_ptr->SetErrorString ("No TLS data currently exists for this thread.");
                     return false;
                 }
 
-                // Convert the TLS offset into the absolute address.
-                Scalar tmp = stack.back().ResolveValue(exe_ctx);
-                stack.back() = tmp + tls_addr;
+                stack.back().GetScalar() = tls_load_addr;
                 stack.back().SetValueType (Value::eValueTypeLoadAddress);
             }
             break;