[PATCH] D31137: [Inliner] Update Inliner code not to subtract CallPenalty twice

[Evgeny Astigeevich via Phabricator via llvm-commits]

eastig created this revision.

Revision 286814 introduced:

  --- llvm/trunk/lib/Analysis/InlineCost.cpp	2016/10/10 21:47:28	283805
  +++ llvm/trunk/lib/Analysis/InlineCost.cpp	2016/11/14 11:14:41	286814
  @@ -1255,7 +1255,9 @@
         Cost -= InlineConstants::InstrCost;
       }
     }
  -
  +  // The call instruction also disappears after inlining.
  +  Cost -= InlineConstants::InstrCost + InlineConstants::CallPenalty;
  +  
     // If there is only one call of the function, and it has internal linkage,
     // the cost of inlining it drops dramatically.
     bool OnlyOneCallAndLocalLinkage =

But the patch did not update Inliner code:

  shouldBeDeferred(Function *Caller, CallSite CS, InlineCost IC,
  ...
    // FIXME: All of this logic should be sunk into getInlineCost. It relies on
    // FIXME: All of this logic should be sunk into getInlineCost. It relies on
    // the internal implementation of the inline cost metrics rather than
    // treating them as truly abstract units etc.
    TotalSecondaryCost = 0;
    // The candidate cost to be imposed upon the current function.
    int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);

As a result CallPenalty is subtracted twice.

The current patch fixes the issue.

I'd like to thank Easwaran who noticed the issue.


https://reviews.llvm.org/D31137

Files:
  lib/Transforms/IPO/Inliner.cpp


Index: lib/Transforms/IPO/Inliner.cpp
===================================================================
--- lib/Transforms/IPO/Inliner.cpp
+++ lib/Transforms/IPO/Inliner.cpp
@@ -289,7 +289,7 @@
   // treating them as truly abstract units etc.
   TotalSecondaryCost = 0;
   // The candidate cost to be imposed upon the current function.
-  int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
+  int CandidateCost = IC.getCost() - 1;
   // This bool tracks what happens if we do NOT inline C into B.
   bool callerWillBeRemoved = Caller->hasLocalLinkage();
   // This bool tracks what happens if we DO inline C into B.


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