[PATCH] D121084: [NewPM][Inliner] Make inlined calls to functions in same SCC as callee exponentially expensive

Mon Mar 7 13:21:16 PST 2022

nikic added a comment.

In D121084#3365187 <https://reviews.llvm.org/D121084#3365187>, @aeubanks wrote:

> I did see a consistent 0.75-1% regression on an important internal benchmark with the other approach (which I believe we actually care about), although some benchmarks are sensitive to alignment.

And the regressions is not present with this variant? If so, yeah, let's go with this.

================
Comment at: llvm/lib/Transforms/IPO/Inliner.cpp:971
+                  CalleeSCC == CG.lookupSCC(CG.get(*NewCallee))) {
+                Attribute NewCBCostMult = Attribute::get(
+                    M.getContext(),
----------------
Should we also fetch the previous multiplier of ICB here and multiply it in? Not sure if it's really relevant in practice, but currently we're only preserving the existing multiplier from CB, but not ICB.

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  https://reviews.llvm.org/D121084/new/

https://reviews.llvm.org/D121084