From 8d9a6bd76aee252616e587c45780b15935393e72 Mon Sep 17 00:00:00 2001 From: Younes Manton Date: Tue, 3 Sep 2024 09:26:02 -0700 Subject: [PATCH] Add extra Simplifier & gotoElim passes to warm/hot If Simplifier detects trivial conditional branches where the fallthrough block is a goto block to the branch target it can remove said branches and leave behind a goto block. The resulting CFG can then potentially be cleaned up by RedundantGotoElimination. Running these two opts before BlockSplitter allows these trivial conditional branches to be completely optimized away before BlockSplitter gets a change to run and potentially duplicate blocks that hide the opportunity and make it harder to detect and eliminate later. This PR inserts Simplifer and RedundantGotoElimination passes before BlockSplitter and moves all 3 after VP, which typically detects opportunities that result in dead code, which when removed, results in the trivial conditional branches that we're interested in. Signed-off-by: Younes Manton --- runtime/compiler/optimizer/J9Optimizer.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/runtime/compiler/optimizer/J9Optimizer.cpp b/runtime/compiler/optimizer/J9Optimizer.cpp index 0d558d2a8d7..d6825abe783 100644 --- a/runtime/compiler/optimizer/J9Optimizer.cpp +++ b/runtime/compiler/optimizer/J9Optimizer.cpp @@ -345,6 +345,8 @@ static const OptimizationStrategy warmStrategyOpts[] = #endif { OMR::localCSE, OMR::IfLoopsAndNotProfiling }, { OMR::idiomRecognition, OMR::IfLoopsAndNotProfiling }, + { OMR::treeSimplification }, + { OMR::redundantGotoElimination, OMR::IfEnabledAndNotJitProfiling }, { OMR::blockSplitter }, { OMR::treeSimplification }, // revisit; not really required ? { OMR::virtualGuardHeadMerger }, @@ -554,8 +556,9 @@ const OptimizationStrategy hotStrategyOpts[] = { OMR::earlyLocalGroup }, { OMR::stripMiningGroup, OMR::IfLoops }, // strip mining in loops { OMR::loopReplicator, OMR::IfLoops }, // tail-duplication in loops - { OMR::blockSplitter, OMR::IfNews }, // treeSimplification + blockSplitter + VP => opportunity for EA { OMR::expensiveGlobalValuePropagationGroup }, + { OMR::redundantGotoElimination, OMR::IfEnabledAndNotJitProfiling }, + { OMR::blockSplitter, OMR::IfNews }, // treeSimplification + blockSplitter + VP => opportunity for EA { OMR::localCSE, OMR::IfVectorAPI }, { OMR::loopCanonicalization, OMR::IfVectorAPI }, { OMR::partialRedundancyEliminationGroup, OMR::IfVectorAPI },