90 //          |   | (Weight = 124)
94 //          | (Weight = 4)
199   /// Special weight used for cases with exact zero probability.
201   /// Minimal possible non zero weight.
203   /// Weight to an 'unreachable' block.
205   /// Weight to a block containing non returning call.
207   /// Weight to 'unwind' block of an invoke instruction.
209   /// Weight to a 'cold' block. Cold blocks are the ones containing calls marked
212   /// Default weight is used in cases when there is no dedicated execution
213   /// weight set. It is not propagated through the domination line either.
415   // If the sum of weights does not fit in 32 bits, scale every weight down  in calcMetadataWeights()
663   // For edges entering a loop take weight of a loop rather than an individual  in getEstimatedEdgeWeight()
677     auto Weight = getEstimatedEdgeWeight({SrcLoopBB, DstLoopBB});  in getMaxEstimatedEdgeWeight()  local
679     if (!Weight)  in getMaxEstimatedEdgeWeight()
682     if (!MaxWeight || *MaxWeight < *Weight)  in getMaxEstimatedEdgeWeight()
683       MaxWeight = Weight;  in getMaxEstimatedEdgeWeight()
689 // Updates \p LoopBB's weight and returns true. If \p LoopBB has already
690 // an associated weight it is unchanged and false is returned.
692 // Please note by the algorithm the weight is not expected to change once set
700   // In general, weight is assigned to a block when it has final value and  in updateEstimatedBlockWeight()
704   // set weight is favored and all consequent weights are ignored.  in updateEstimatedBlockWeight()
731 // successor has updated estimated weight.
740   // TODO: Consider propagating weight down the domination line as well.  in propagateEstimatedBlockWeight()
752     // Don't propagate weight to blocks belonging to different loops.  in propagateEstimatedBlockWeight()
756         // If DomBB has weight set then all it's predecessors are already  in propagateEstimatedBlockWeight()
757         // processed (since we propagate weight up to the top of IR each time).  in propagateEstimatedBlockWeight()
777   // Important note regarding the order of checks. They are ordered by weight  in getInitialEstimatedBlockWeight()
805 // best to propagate the weight to up/down the IR.
817       // If we were able to find estimated weight for the block set it to this  in computeEestimateBlockWeight()
823   // successor/exit having estimated weight. Try to propagate weight to such  in computeEestimateBlockWeight()
858       // weight of "hot" path. In theory we can probably find a better function  in computeEestimateBlockWeight()
873 // Calculate edge probabilities based on block's estimated weight.
887   // Changed to 'true' if at least one successor has estimated weight.  in calcEstimatedHeuristics()
893     std::optional<uint32_t> Weight;  in calcEstimatedHeuristics()  local
897     Weight = getEstimatedEdgeWeight(Edge);  in calcEstimatedHeuristics()
900         // Avoid adjustment of ZERO weight since it should remain unchanged.  in calcEstimatedHeuristics()
901         Weight != static_cast<uint32_t>(BlockExecWeight::ZERO)) {  in calcEstimatedHeuristics()
902       // Scale down loop exiting weight by trip count.  in calcEstimatedHeuristics()
903       Weight = std::max(  in calcEstimatedHeuristics()
905           Weight.value_or(static_cast<uint32_t>(BlockExecWeight::DEFAULT)) /  in calcEstimatedHeuristics()
910         // Avoid adjustment of ZERO weight since it should remain unchanged.  in calcEstimatedHeuristics()
911         Weight != static_cast<uint32_t>(BlockExecWeight::ZERO)) {  in calcEstimatedHeuristics()
912       // 'Unlikely' blocks have twice lower weight.  in calcEstimatedHeuristics()
913       Weight = std::max(  in calcEstimatedHeuristics()
915           Weight.value_or(static_cast<uint32_t>(BlockExecWeight::DEFAULT)) / 2);  in calcEstimatedHeuristics()
918     if (Weight)  in calcEstimatedHeuristics()
922         Weight.value_or(static_cast<uint32_t>(BlockExecWeight::DEFAULT));  in calcEstimatedHeuristics()
927   // If non of blocks have estimated weight bail out.  in calcEstimatedHeuristics()
928   // If TotalWeight is 0 that means weight of each successor is 0 as well and  in calcEstimatedHeuristics()
936   // If the sum of weights does not fit in 32 bits, scale every weight down  in calcEstimatedHeuristics()
948     assert(TotalWeight <= UINT32_MAX && "Total weight overflows");  in calcEstimatedHeuristics()