Re: Help with Live Range Analysis?

Hans,


My representation is intended to just show the use of variables and
control flow of the microcode as extracted from the source code. The
actual mapping of those variables to registers (as chosen by the
programmer) can also be extracted from the source code but is not
represented.


I was hoping to break this into two problems:


The first problem is to understand for each variable which other
variables interfere with it (i.e have overlapping live ranges). For
this, I was hoping a tool existed to take a simple representation of
the control flow and data flow and provide a report. That is what I
was trying to show with my sample code.


The second problem is to process the report to prove or disprove that
for each variable no other variable has been mapped to the same
register. This is easy for me to do once the first problem is solved.


In addition to these, I also thought it would be nice if for each line
in my simple represnetation, I could get a report of all variables
that are alive at that line.


I hope this clarifies.


John




Hans-Peter Diettrich wrote:
> John Carney wrote:
>>I am working on a microcode project where register allocation is done
>>by the programmer. There is nothing which prevents the programmer from
>>allocating two or more variables to the same register and then
>>inadvertently writing code with overlapping live ranges for those
>>variables. The microcode assembler trusts the register allocation and
>>this results in (numerous) bugs which are difficult to find.
>
> After thinking myself, and reading the various replies, I'm not really
> sure what you want to find out. Is it the content (variable-alias) of
> the registers at any place in your code? ...

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