From c92712184faf007afa28503da77e9a962dceb8cc Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 1 Nov 2009 19:09:12 +0000 Subject: [PATCH] only run GlobalDCE at -O3 and run it late instead of early. GlobalOpt already deletes trivially dead functions/globals, so GlobalDCE only adds values for cycles of dead things. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85731 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/StandardPasses.h | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/include/llvm/Support/StandardPasses.h b/include/llvm/Support/StandardPasses.h index d7a3dc059f4..ff0a6d69917 100644 --- a/include/llvm/Support/StandardPasses.h +++ b/include/llvm/Support/StandardPasses.h @@ -99,7 +99,7 @@ namespace llvm { PM->add(createCFGSimplificationPass()); // Clean up disgusting code if (UnitAtATime) { PM->add(createGlobalOptimizerPass()); // Optimize out global vars - PM->add(createGlobalDCEPass()); // Remove unused fns and globs + PM->add(createIPSCCPPass()); // IP SCCP PM->add(createDeadArgEliminationPass()); // Dead argument elimination } @@ -149,10 +149,15 @@ namespace llvm { if (UnitAtATime) { PM->add(createStripDeadPrototypesPass()); // Get rid of dead prototypes PM->add(createDeadTypeEliminationPass()); // Eliminate dead types - } - if (OptimizationLevel > 1 && UnitAtATime) - PM->add(createConstantMergePass()); // Merge dup global constants + // GlobalOpt already deletes dead functions and globals, at -O3 try a + // late pass of GlobalDCE. It is capable of deleting dead cycles. + if (OptimizationLevel > 2) + PM->add(createGlobalDCEPass()); // Remove dead fns and globals. + + if (OptimizationLevel > 1) + PM->add(createConstantMergePass()); // Merge dup global constants + } } static inline void addOnePass(PassManager *PM, Pass *P, bool AndVerify) { -- 2.34.1