[LLVMdev] Extracting all BasicBlocks of a Function into new Function

[Chris Lattner]

On Mon, 2 Oct 2006, Bram Adams wrote:
> So, I wonder what problems may show up in this algorithm (steps 4, 5
> and 6 seem to be crucial). The vararg-case could be a problem in step
> 5, although the va_start intrinsic isn't tied to the surrounding
> Function at first sight.

There is an implicit dependency between vastart and the function it 
lives in.  Specifically, if you have:

void foo(int X, ...) {
   P = va_start();
   use(P);
}

You can't change this to:

void foo(int X, ...) {
   bar(X);
}

void bar(int X, ...) {
   P = va_start();
   use(P);
}

You'd have to change it to something like:

void foo(int X, ...) {
   P = va_start();
   bar(X, P);
}

void bar(int X, valist P) {
   use(P);
}


-Chris

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