Refine the reporting mechanism for interruption.

Also, make it possible for new Targets which haven't been added to
the TargetList yet to check for interruption, and add a few more
places in building modules where we can check for interruption.

Differential Revision: https://reviews.llvm.org/D154542

1 files changed, 22 insertions, 14 deletions

diff --git a/lldb/source/Commands/CommandObjectFrame.cpp b/lldb/source/Commands/CommandObjectFrame.cpp
index db31b15..3f68425 100644
--- a/lldb/source/Commands/CommandObjectFrame.cpp
+++ b/lldb/source/Commands/CommandObjectFrame.cpp
@@ -326,21 +326,29 @@ protected:
         }
       } else if (*m_options.relative_frame_offset > 0) {
         // I don't want "up 20" where "20" takes you past the top of the stack
-        // to produce
-        // an error, but rather to just go to the top.  So I have to count the
-        // stack here...
-        const uint32_t num_frames = thread->GetStackFrameCount();
-        if (static_cast<int32_t>(num_frames - frame_idx) >
-            *m_options.relative_frame_offset)
-          frame_idx += *m_options.relative_frame_offset;
+        // to produce an error, but rather to just go to the top.  OTOH, start
+        // by seeing if the requested frame exists, in which case we can avoid 
+        // counting the stack here...
+        const uint32_t frame_requested = frame_idx 
+            + *m_options.relative_frame_offset;
+        StackFrameSP frame_sp = thread->GetStackFrameAtIndex(frame_requested);
+        if (frame_sp)
+          frame_idx = frame_requested;
         else {
-          if (frame_idx == num_frames - 1) {
-            // If we are already at the top of the stack, just warn and don't
-            // reset the frame.
-            result.AppendError("Already at the top of the stack.");
-            return false;
-          } else
-            frame_idx = num_frames - 1;
+          // The request went past the stack, so handle that case:
+          const uint32_t num_frames = thread->GetStackFrameCount();
+          if (static_cast<int32_t>(num_frames - frame_idx) >
+              *m_options.relative_frame_offset)
+          frame_idx += *m_options.relative_frame_offset;
+          else {
+            if (frame_idx == num_frames - 1) {
+              // If we are already at the top of the stack, just warn and don't
+              // reset the frame.
+              result.AppendError("Already at the top of the stack.");
+              return false;
+            } else
+              frame_idx = num_frames - 1;
+          }
         }
       }
     } else {