[PATCH] D19773: Tweak the ThinLTO pass pipeline
Teresa Johnson via llvm-commits
llvm-commits at lists.llvm.org
Thu May 5 18:39:08 PDT 2016
tejohnson added a comment.
I compared performance of all the C/C++ benchmarks in SPEC cpu2006 on an Ivybridge X86 with gold+ThinLTO, with 3 runs each. It looks performance neutral (some run-to-run variations that look like noise, nothing significant).
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Comment at: lib/Transforms/IPO/PassManagerBuilder.cpp:428
@@ -432,1 +427,3 @@
+ if (PerformThinLTO)
+ // Optimize globals now when performing ThinLTO, this enables more
----------------
Is there any significance to the move of the globalopt invocation here from its original location below LoopVersioningLICM?
================
Comment at: lib/Transforms/IPO/PassManagerBuilder.cpp:448
@@ -447,3 @@
- MPM.add(createGlobalOptimizerPass());
- // Remove dead fns and globals after globalopt.
- MPM.add(createGlobalDCEPass());
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Why are the globalDCE before and after globalopt no longer needed (for the reasons stated in the comments)?
http://reviews.llvm.org/D19773
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