[LLVMdev] Inter-procedural program flow analysis

[Jim Grosbach]

Isn't this effectively the halting problem? Consider the case where block Y is the exit block of main() and block X is the entry block of main().

Jim


On Oct 2, 2012, at 4:29 PM, Stephen Schiffli <sschiffli at gmail.com> wrote:

> Is there any inter-procedural analysis that could tell me if some BasicBlock Y is guaranteed to execute based on my knowledge that BasicBlock X will execute?  For example:
> 
> 
> 
> extern int x;
> 
> void foo() { }
> 
> int main() {
> 
>             if (x) {
> 
>                         foo();
> 
>             } else {
> 
>                         foo();
> 
> }
> 
> }
> 
>  
> I want to be told that the entry block of foo is guaranteed to be executed since I know the entry block of main is guaranteed to be executed.  Basically that all paths from X to program termination go through Y at some point.  Please ignore the folding of identical branches and function in-lining, I want to use this type of analysis in the general case.
> 
> 
> 
> Thanks,
> 
> -Stephen
> 
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