[LLDB][MIPS] Fix hit_count for mips watchpoints

[mohit.bhakkad]

Summary

Revise hit counts when hit a false positive

[jasonmolenda]

Greg's out this week, he or Jim may want to comment.

I was curious about this method IncrementFalseAlarmsAndReviseHitCount, there weren't any calls to it. A little digging shows that the one use of it was removed in r166472.

What does it mean if you get a watchpoint exception on your machine, but you didn't have a watchpoint set on that address. Is there something else going on here?

[zturner]

Can you add a test for this?

[mohit.bhakkad]

Jason, in MIPS watch registers, last 3 bits of watchpoint addresses are masked by IRW(instruction, read, write types) flags,
so machine gives exception for any address having other bits same to the actual watch address execept last 3 bits.
Comment at line number 749 in below code gives an such example.

Zachary, TestMyFirstWatchpoint.py already covers this case.

[jasonmolenda]

I see, this seems reasonable to me.

[zturner]

Ahh, so the test was already failing and you're just fixing it? That's
fine then, thanks.

[clayborg]

Back from vacation, sorry for the delay. Looks good.

lldb/trunk/source/Target/StopInfo.cpp

PerformAction (Event *event_ptr)
                  * server emulates the instruction at PC and finds the base address of the load/store
                  * instruction and appends it in the description of the stop-info packet. If watchpoint
                  * is not set on this address by user then this do not stop.
                 */
                 if (m_watch_hit_addr != LLDB_INVALID_ADDRESS)
                 {
                     WatchpointSP wp_hit_sp = thread_sp->CalculateTarget()->GetWatchpointList().FindByAddress(m_watch_hit_addr);
                     if (!wp_hit_sp)
+                    {
                         m_should_stop = false;
+                        wp_sp->IncrementFalseAlarmsAndReviseHitCount();
+                    }
                 }
-                
                 if (m_should_stop && wp_sp->GetConditionText() != NULL)
                 {
                     // We need to make sure the user sees any parse errors in their condition, so we'll hook the
                     // constructor errors up to the debugger's Async I/O.
                     ExpressionResults result_code;
                     EvaluateExpressionOptions expr_options;
                     expr_options.SetUnwindOnError(true);
                     expr_options.SetIgnoreBreakpoints(true);