On Tue, Nov 22, 2011 at 10:32 PM, Jeff Garzik <jeff@xxxxxxxxxx> wrote:
> The disassembler output is certainly sane and understandable. Here's an
> example test case:
>
> extern int bar(int x);
>
> int foo (int x)
> {
> int y = 0;
> while (y < 1000) {
> y += bar(x);
> }
>
> return y;
> }
>
> The PHI operation in SSA being a union of control flows, we need to
> reference all input pseudos ... including pseudos generated by operations
> further down the in the code (i.e. pseudos not yet generated).
>
> A classic forward reference is needed, and I cannot figure out how to do
> that in the LLVM C API, even though the forward reference is plain and
> obvious in the LLVM text disassembly. My next step was going to trace
> through the front end to see how it generates forward refs, or be lazy and
> brain dump on an llvm mailing list somewhere.
So pasting the above test program to http://llvm.org/demo/ and
switching to "LLVM C++ API code" target seems to suggest you're
interested in the LLVMReplaceAllUsesWith() API for forward references.
Pekka
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