[LLVMdev] Get identifier for unnamed temporary

[Bill Wendling]

On Thu, Jul 2, 2009 at 3:00 PM, Scott Ricketts<sricketts at maxentric.com> wrote:
> On Thu, Jul 2, 2009 at 2:48 PM, Chris Lattner<clattner at apple.com> wrote:
>> VMCore will auto-unique value names for you.  Most passes just create
>> all instructions with a name like "tmp" and let VMCore unique them.
>> Is this enough for you?
>
> On Thu, Jul 2, 2009 at 2:50 PM, Eli Friedman<eli.friedman at gmail.com> wrote:
>> The relevant code is llvm/lib/VMCore/AsmWriter.cpp.  That said, you
>> shouldn't really need them anywhere; what are you trying to do?
>
>
> I am adding some instrumentation that requires me to track information
> associated with llvm values. I need a good way to identify these
> values by passing a unique id (can be unique within function scope) to
> the instrumenting function. Let me be more clear with an example.
>
> If I have
>
> %3 = add i32 %1, %2
>
> then I would like to insert a function call that will somehow log that
> %3 requires %1 and %2 to be computed at this step. So my original plan
> was to have my pass create a mapping of identifiers to numerical
> constants, and then to pass the appropriate constants to the
> instrumenting function at runtime.
>
> Is there a better approach?
>
If your pass were to map "Instruction*" to a vector of "Value*"s, then
that might work. LLVM's IR is in SSA form, so that information is
pretty much already available by just looking at the Instruction's
operands.

-bw