Fix step-over when SymbolContext.function is missing and symbol is present.

[sammccall]

Summary

Fix step-over when SymbolContext.function is missing and symbol is present.

With targets from our build configuration,
ThreadPlanStepOverRange::IsEquivalentContext fails to fire for relevant frames,
leading to ShouldStop() returning true prematurely.

The frame's SymbolContext, and m_addr_context have:

• comp_unit set and matching
• function = nullptr
• symbol set and matching (but this is never checked)

My naive guess is that the context should be equivalent in this case :-)

[sammccall]

• Always reject different compilation units

[jingham]

That way of doing it is fine too.

[sammccall]

• Restore old behaviour when blocks are unequal

[jingham]

Excellent, thanks for catching that.

lldb/trunk/source/Target/ThreadPlanStepOverRange.cpp

bool ThreadPlanStepOverRange::IsEquivalentContext(
     const SymbolContext &context) {
   // Match as much as is specified in the m_addr_context:
   // This is a fairly loose sanity check.  Note, sometimes the target doesn't
   // get filled
   // in so I left out the target check.  And sometimes the module comes in as
   // the .o file from the
   // inlined range, so I left that out too...
   if (m_addr_context.comp_unit) {
-    if (m_addr_context.comp_unit == context.comp_unit) {
-      if (m_addr_context.function &&
-          m_addr_context.function == context.function) {
-        // It is okay to return to a different block of a straight function, we
-        // only have to
-        // be more careful if returning from one inlined block to another.
-        if (m_addr_context.block->GetInlinedFunctionInfo() == nullptr &&
-            context.block->GetInlinedFunctionInfo() == nullptr)
-          return true;
-
-        if (m_addr_context.block && m_addr_context.block == context.block)
-          return true;
-      }
-    }
-  } else if (m_addr_context.symbol && m_addr_context.symbol == context.symbol) {
+    if (m_addr_context.comp_unit != context.comp_unit)
+      return false;
+    if (m_addr_context.function) {
+      if (m_addr_context.function != context.function)
+        return false;
+      return m_addr_context.block == context.block;
+  // Fall back to symbol if we have no decision from comp_unit/function/block.
+  if (m_addr_context.symbol && m_addr_context.symbol == context.symbol) {
     return true;
   }
   return false;
 }
 
 bool ThreadPlanStepOverRange::ShouldStop(Event *event_ptr) {
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));