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 <[email protected]>
eclipse-openj9 · Sep 9, 2024 · 8d9a6bd · 8d9a6bd
1 parent 90ac2bf
commit 8d9a6bd
Showing 1 changed file with 4 additions and 1 deletion.
diff --git 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 },