[lldb] Add an extra optional did_read_live_memory to Target::ReadMemory

lldb/include/lldb/Target/Target.h

@@ -1110,10 +1110,16 @@ class Target : public std::enable_shared_from_this<Target>,
   // 2 - if there is a process, then read from memory
   // 3 - if there is no process, then read from the file cache
   //
+  // If did_read_live_memory is provided, will indicate if the read was from
+  // live memory, or from file contents. A caller which needs to treat these two
+  // sources differently should use this argument to disambiguate where the data
+  // was read from.
+  //
   // The method is virtual for mocking in the unit tests.
   virtual size_t ReadMemory(const Address &addr, void *dst, size_t dst_len,
                             Status &error, bool force_live_memory = false,
-                            lldb::addr_t *load_addr_ptr = nullptr);
+                            lldb::addr_t *load_addr_ptr = nullptr,
+                            bool *did_read_live_memory = nullptr);
 
   size_t ReadCStringFromMemory(const Address &addr, std::string &out_str,
                                Status &error, bool force_live_memory = false);

lldb/source/Target/Target.cpp

@@ -1987,8 +1987,11 @@ size_t Target::ReadMemoryFromFileCache(const Address &addr, void *dst,
 
 size_t Target::ReadMemory(const Address &addr, void *dst, size_t dst_len,
                           Status &error, bool force_live_memory,
-                          lldb::addr_t *load_addr_ptr) {
+                          lldb::addr_t *load_addr_ptr,
+                          bool *did_read_live_memory) {
   error.Clear();
+  if (did_read_live_memory)
+    *did_read_live_memory = false;
 
   Address fixed_addr = addr;
   if (ProcessIsValid())
@@ -2086,6 +2089,8 @@ size_t Target::ReadMemory(const Address &addr, void *dst, size_t dst_len,
       if (bytes_read) {
         if (load_addr_ptr)
           *load_addr_ptr = load_addr;
+        if (did_read_live_memory)
+          *did_read_live_memory = true;
         return bytes_read;
       }
     }

lldb/unittests/Expression/DWARFExpressionTest.cpp

@@ -111,7 +111,8 @@ class MockTarget : public Target {
 
   size_t ReadMemory(const Address &addr, void *dst, size_t dst_len,
                     Status &error, bool force_live_memory = false,
-                    lldb::addr_t *load_addr_ptr = nullptr) /*override*/ {
+                    lldb::addr_t *load_addr_ptr = nullptr,
+                    bool *did_read_live_memory = nullptr) /*override*/ {
     auto expected_memory = this->ReadMemory(addr.GetOffset(), dst_len);
     if (!expected_memory) {
       llvm::consumeError(expected_memory.takeError());