[llvm-dev] Back tracing Variables

[Juan Ceasar via llvm-dev]

Don,

Thanks so much, I think that’s pretty much what I was looking for!  


> On Dec 23, 2016, at 10:25 AM, don hinton <hintonda at gmail.com> wrote:
> 
> Hi Juan:
> 
> I haven't looked at SlotTracker, but have been using MemoryDependenceWrapperPass to do something similar.
> 
> hth...
> don
> 
> On Fri, Dec 23, 2016 at 5:55 AM, Juan Ceasar via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> Good Morning - Happy Holidays everyone!
> 
> I had a question about the best way to do back tracing of variables via the IR.  So for example, if I have the following simple IR:
> 
> define i32 @squak(i32 %num) #0 {
>   %1 = alloca i32, align 4
>   store i32 %num, i32* %1, align 4
>   %2 = load i32, i32* %1, align 4
>   %3 = icmp sgt i32 %2, 10
> 
> I’m grabbing the predicate of “icmp”, which in this case is a simple test “>”  of the input “%num" and the constant “10" and I want to trace back to “%num" via the slots/virtual registers %2 and %1.  I believe I can do this via the SlotTracker (in AsmWriter.cpp) but I wonder if there’s a better, more direct way?  Any suggestions?  I’m basically trying to track predicate formation in the IR and hence the need…
> 
> Thanks for any help!
> 
> 
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