[PATCH] D120908: [FuncSpec] Enable function specialize for a constant range of arguments.

[Chuanqi Xu via Phabricator via llvm-commits]

ChuanqiXu added a comment.

Personally, I feel the design principle of current FuncSpec is to leave opportunities to IPSCCP if possible. I guess the main concern may be compilation time.
(Although I feel FuncSpec could cover IPSCCP.)



================
Comment at: llvm/lib/Transforms/IPO/FunctionSpecialization.cpp:686-693
+    // If the argument is Constant, there's nothing to do. IPSCCP will
+    // propagate the argument.
+    if (isConstant(Solver.getLatticeValueFor(A))) {
       LLVM_DEBUG(dbgs() << "FnSpecialization: Nothing to do, argument "
                         << A->getNameOrAsOperand()
                         << " is already constant?\n");
       return false;
----------------
My personal feeling is that FuncSpec might be able to replace IPSCCP completely if FuncSpec is ready enough. I tried to remove the whole check here in downstream and didn't see any regression in performance. (I didn't measure compile time though).


Repository:
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  https://reviews.llvm.org/D120908/new/

https://reviews.llvm.org/D120908