RE: [Qemu-devel] Counting Instructions and Looking for ConditionalBranches

[Torbjorn.K.Andersson]

Hello Shane.
 
I have successfully added instruction counters to QEMU with a low run-time 
overhead. I cannot give you the code but I can tell you how I did it.
 
1: Make sure that QEMU knows which block is the current_tb. What I did was to 
update the goto_tb block to update the current_tb pointer.
2: Add an epilogue to the basic blocks that uses the current_tb pointer and 
increase the instruction counter with the information stored in the current_tb. 
In my test system it was a one to one mapping with the size of the TB.
 
The files you will need to update are: exec.c and translate.c together with 
op.c for your target. Maybe more..

/Regards
Torbjörn Andersson
________________________________

From: address@hidden [mailto:address@hidden On Behalf Of Shane Brennan
Sent: den 18 februari 2007 03:08
To: address@hidden
Subject: [Qemu-devel] Counting Instructions and Looking for ConditionalBranches
        
        
I am wondering if anyone knows where in the QEMU source code I can create a 
counter to count the number of executed instructions? In addition, where I can 
place an IF statement to see if a conditional branch instruction is about to 
execute. 
        
I need to do this to create a basic block vector for SimPoint. I have found 
that the function cpu-exec in cpu-exec.c is probably going to be involved, but 
I would appreciate any help in narrowing things down. Basically, all I need to 
do is at every instruction I increase a counter. Then, I see if that 
instruction is a conditional branch. If it is, I print some characters to a 
file, and reset the counter. I would greatly appreciate any help. 
        
        ~Shane