Mill Computing, Inc. Forums The Mill Architecture Grab bag of questions Reply To: Grab bag of questions

Ivan Godard
Post count: 656

– 10) Specializer hints
The tool chain already responds to some of the hint info that LLVM provides. In addition, our dumper (IR to genAsm shim) extracts some info known to LLVM that is not in the IR from LLVM internal structures and adds to the genAsm. An example is the ordering dependency oracle in the genAsm for each function body, which encompasses what LLLVM knows from the aliasing info and function body analysis. Generally we want to push that sort of info and analysis into the steps before genAsm, and let the specializer use the result of the analysis (such as required ordering) without doing the analysis itself.

For your specific examples:
* aliasing is reflected in the oracle; potentially colliding references have an oracle entry giving the textual order
* flags are local in the architecture; ops that change global flags are ordered in the oracle w/r/t ops that use them
* loops should not be unrolled; SSA form (in the IR and genAsm) eliminates most references and the pipelining preserves order across iterations for the rest