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LLVM backend for 6502
that can have a big effect :). The first is to enable the iterative SCC passmanager juice that kicks in when the scc passmgr detects that a function pass has devirtualized a call. In this case, it will rerun all the passes it manages on the SCC, up to the iteration count limit (4). This is useful because a function pass may devirualize a call, and we want the inliner to inline it, or pruneeh to infer stuff about it, etc. The second patch is to add *all* call sites to the DevirtualizedCalls list the inliner uses. This list is about to get renamed, but the jist of this is that the inliner now reconsiders *all* inlined call sites as candidates for further inlining. The intuition is this that in cases like this: f() { g(1); } g(int x) { h(x); } We analyze this bottom up, and may decide that it isn't profitable to inline H into G. Next step, we decide that it is profitable to inline G into F, and do so, which means that F now calls H. Even though the call from G -> H may not have been profitable to inline, the call from F -> H may be (in this case because a constant allows folding etc). In my spot checks, this doesn't have a big impact on code. For example, the LLC output for 252.eon grew from 0.02% (from 317252 to 317308) and 176.gcc actually shrunk by .3% (from 1525612 to 1520964 bytes). 252.eon never iterated in the SCC Passmgr, 176.gcc iterated at most 1 time. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102823 91177308-0d34-0410-b5e6-96231b3b80d8 |
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