diff options
Diffstat (limited to 'source/slang/slang-ir-dce.cpp')
| -rw-r--r-- | source/slang/slang-ir-dce.cpp | 42 |
1 files changed, 15 insertions, 27 deletions
diff --git a/source/slang/slang-ir-dce.cpp b/source/slang/slang-ir-dce.cpp index c6636aaee..c00e4ca7b 100644 --- a/source/slang/slang-ir-dce.cpp +++ b/source/slang/slang-ir-dce.cpp @@ -29,30 +29,15 @@ struct DeadCodeEliminationContext // there could be new DCE opportunities. bool phiRemoved = false; - // Our overall process is going to be to determine - // which instructions in the module are "live" - // and then eliminate anything that wasn't found to - // be live. - // - // We will track the liveness state by keeping - // a set of all instructions we have so far determined - // to be live. - // - HashSet<IRInst*> liveInsts; - // Querying whether an instruction has been // determined to be live is easy. + // To speedup the test, we use the + // `scratchData` field of each inst as the marker. // - bool isInstLive(IRInst* inst) + bool isInstAlive(IRInst* inst) { - // The only wrinkle is that we want to safeguard - // against a null instruction (there are some - // corner cases where we still construct IR - // instructions with a null type). - // - if(!inst) return false; - - return liveInsts.contains(inst); + if (!inst) return false; + return inst->scratchData != 0; } // We are going to do an iterative analysis @@ -81,10 +66,11 @@ struct DeadCodeEliminationContext // if(!inst) return; - if(liveInsts.contains(inst)) - return; - liveInsts.add(inst); - workList.add(inst); + if (!inst->scratchData) + { + inst->scratchData = 1; + workList.add(inst); + } } IRInst* getUndefInst() @@ -109,7 +95,9 @@ struct DeadCodeEliminationContext for (;;) { - liveInsts.clear(); + // Clear the `alive` bits by initializing all scratchData to 0. + initializeScratchData(root); + workList.clear(); // First of all, we know that the root instruction @@ -242,7 +230,7 @@ struct DeadCodeEliminationContext // // The easy case is if `inst` is dead (that is, not live). // - if( !isInstLive(inst) ) + if( !isInstAlive(inst) ) { // We can simply remove and deallocate `inst` because it is // dead, and not worry about any of its descendents, @@ -324,7 +312,7 @@ bool shouldInstBeLiveIfParentIsLive(IRInst* inst, IRDeadCodeEliminationOptions o // First, if `inst` is an instruction that might have some effects // when it is executed, then we should keep it around. // - if (inst->mightHaveSideEffects()) + if (inst->mightHaveSideEffects(SideEffectAnalysisOptions::UseDominanceTree)) { return true; } |