12 /// This pass inserts BLOCK, LOOP, and TRY markers to mark the start of scopes,
96   // For each BLOCK|LOOP|TRY, the corresponding END_(BLOCK|LOOP|TRY) or DELEGATE
97   // (in case of TRY).
99   // For each END_(BLOCK|LOOP|TRY) or DELEGATE, the corresponding
100   // BLOCK|LOOP|TRY.
102   // <TRY marker, EH pad> map
104   // <EH pad, TRY marker> map
150                 "Insert BLOCK/LOOP/TRY markers for WebAssembly scopes", false,
250 // try) signatures when we implement the multi-value proposal later.
314     // If there is a previously placed BLOCK/TRY marker and its corresponding  in placeBlockMarker()
319         MI.getOpcode() == WebAssembly::TRY) {  in placeBlockMarker()
329     // All END_(BLOCK|LOOP|TRY) markers should be before the BLOCK.  in placeBlockMarker()
365     // END_BLOCK should precede existing LOOP and TRY markers.  in placeBlockMarker()
367         MI.getOpcode() == WebAssembly::TRY)  in placeBlockMarker()
487   // If this try is at the bottom of the function, insert a dummy block at the  in placeTryMarker()
518   // Decide where in Header to put the TRY.  in placeTryMarker()
520   // Instructions that should go before the TRY.  in placeTryMarker()
522   // Instructions that should go after the TRY.  in placeTryMarker()
526     // loop is above MBB, it should be after the TRY, because the loop is nested  in placeTryMarker()
527     // in this TRY. Otherwise it should be before the TRY.  in placeTryMarker()
538     // All previously inserted BLOCK/TRY markers should be after the TRY because  in placeTryMarker()
541         MI.getOpcode() == WebAssembly::TRY)  in placeTryMarker()
545     // All END_(BLOCK/LOOP/TRY) markers should be before the TRY.  in placeTryMarker()
552     // Terminators should go after the TRY.  in placeTryMarker()
557   // If Header unwinds to MBB (= Header contains 'invoke'), the try block should  in placeTryMarker()
558   // contain the call within it. So the call should go after the TRY. The  in placeTryMarker()
584   // Local expression tree should go after the TRY.  in placeTryMarker()
586   // BB's terminator, but in TRY's case, we should start from the previous  in placeTryMarker()
601   // Add the TRY.  in placeTryMarker()
605               TII.get(WebAssembly::TRY))  in placeTryMarker()
625     // where TRY marker is, this loop is contained within the 'catch' part, so  in placeTryMarker()
626     // the END_TRY marker should go after that. Otherwise, the whole try-catch  in placeTryMarker()
629       // For a LOOP to be after TRY, LOOP's BB should be after TRY's BB; if they  in placeTryMarker()
630       // are in the same BB, LOOP is always before TRY.  in placeTryMarker()
642   // Mark the end of the TRY.  in placeTryMarker()
650   // mappings: (BB with 'end_try' -> BB with 'try') and (BB with 'catch' -> BB  in placeTryMarker()
651   // with 'try'). We need to create 'catch' -> 'try' mapping here too because  in placeTryMarker()
655   // try  in placeTryMarker()
671   //   try  in removeUnnecessaryInstrs()
683   //   try  in removeUnnecessaryInstrs()
684   //     try  in removeUnnecessaryInstrs()
710       MachineInstr *Try = EHPadToTry[Cont];  in removeUnnecessaryInstrs()  local
711       MachineInstr *EndTry = BeginToEnd[Try];  in removeUnnecessaryInstrs()
742   // When there are block / end_block markers that overlap with try / end_try  in removeUnnecessaryInstrs()
743   // markers, and the block and try markers' return types are the same, the  in removeUnnecessaryInstrs()
744   // block /end_block markers are not necessary, because try / end_try markers  in removeUnnecessaryInstrs()
747   //   try  in removeUnnecessaryInstrs()
756       if (MI.getOpcode() != WebAssembly::TRY)  in removeUnnecessaryInstrs()
758       MachineInstr *Try = &MI, *EndTry = BeginToEnd[Try];  in removeUnnecessaryInstrs()  local
762       MachineBasicBlock *TryBB = Try->getParent();  in removeUnnecessaryInstrs()
764       int64_t RetType = Try->getOperand(0).getImm();  in removeUnnecessaryInstrs()
765       for (auto B = Try->getIterator(), E = std::next(EndTry->getIterator());  in removeUnnecessaryInstrs()
844 // Wrap the given range of instruction with try-delegate. RangeBegin and
856   // after the nested TRY.  in addTryDelegate()
869   // Create the nested try instruction.  in addTryDelegate()
872   MachineInstr *Try = BuildMI(*BeginBB, TryPos, RangeBegin->getDebugLoc(),  in addTryDelegate()  local
873                               TII.get(WebAssembly::TRY))  in addTryDelegate()
964   registerTryScope(Try, Delegate, nullptr);  in addTryDelegate()
968   // Linearizing the control flow by placing TRY / END_TRY markers can create  in fixCallUnwindMismatches()
976   // discussed how to define the semantics when 'delegate''s target is a non-try  in fixCallUnwindMismatches()
978   // outer try-catch. But anyway our LLVM backend currently does not generate  in fixCallUnwindMismatches()
981   // try  in fixCallUnwindMismatches()
982   //   try  in fixCallUnwindMismatches()
984   //       try  in fixCallUnwindMismatches()
985   //         try  in fixCallUnwindMismatches()
1011   // And the CFG is sorted in this order. Then after placing TRY markers, it  in fixCallUnwindMismatches()
1013   // try  in fixCallUnwindMismatches()
1014   //   try  in fixCallUnwindMismatches()
1026   // call with an inner try-delegate that rethrows the exception to the right  in fixCallUnwindMismatches()
1029   // try  in fixCallUnwindMismatches()
1030   //   try  in fixCallUnwindMismatches()
1032   //     try               ;; (new)  in fixCallUnwindMismatches()
1055   // And the CFG is sorted in this order. Then after placing TRY markers, it  in fixCallUnwindMismatches()
1057   // try  in fixCallUnwindMismatches()
1068   // try  in fixCallUnwindMismatches()
1070   //   try                  ;; (new)  in fixCallUnwindMismatches()
1082   // can be wrapped together in one nested try-delegate scope. (In 1, this  in fixCallUnwindMismatches()
1088   // Range of intructions to be wrapped in a new nested try/catch. A range  in fixCallUnwindMismatches()
1091   // In original CFG, <unwind destination BB, a vector of try ranges>  in fixCallUnwindMismatches()
1100       if (MI.getOpcode() == WebAssembly::TRY)  in fixCallUnwindMismatches()
1205       if (MI.getOpcode() == WebAssembly::TRY)  in fixCallUnwindMismatches()
1221   // Now we fix the mismatches by wrapping calls with inner try-delegates.  in fixCallUnwindMismatches()
1233       // are going to wrap the invoke with try-delegate, making the 'delegate'  in fixCallUnwindMismatches()
1258   // try  in fixCatchUnwindMismatches()
1259   //   try  in fixCatchUnwindMismatches()
1278   // try-delegate, so we wrap the whole try-catch-end with a try-delegate and  in fixCatchUnwindMismatches()
1280   // try  in fixCatchUnwindMismatches()
1281   //   try                     ;; (new)  in fixCatchUnwindMismatches()
1282   //     try  in fixCatchUnwindMismatches()
1301       if (MI.getOpcode() == WebAssembly::TRY)  in fixCatchUnwindMismatches()
1358     MachineInstr *Try = EHPadToTry[EHPad];  in fixCatchUnwindMismatches()  local
1359     MachineInstr *EndTry = BeginToEnd[Try];  in fixCatchUnwindMismatches()
1360     addTryDelegate(Try, EndTry, UnwindDest);  in fixCatchUnwindMismatches()
1364   // Adding a try-delegate wrapping an existing try-catch-end can make existing  in fixCatchUnwindMismatches()
1372   //     try  in fixCatchUnwindMismatches()
1380   // Suppose this try-catch-end has a catch unwind mismatch, so we need to wrap  in fixCatchUnwindMismatches()
1381   // this with a try-delegate. Then this becomes:  in fixCatchUnwindMismatches()
1388   //     try       ;; (new instruction)  in fixCatchUnwindMismatches()
1389   //       try  in fixCatchUnwindMismatches()
1406   // in between, so we try to find the next BB with 'end_block' instruction. In  in fixCatchUnwindMismatches()
1495         // If a 'try''s return type is fixed, both its try body and catch body  in fixEndsAtEndOfFunction()
1534 /// Insert LOOP/TRY/BLOCK markers at appropriate places.
1546       // Place the TRY for MBB if MBB is the EH pad of an exception.  in placeMarkers()
1589   // corresponding try's end_try BB because Stack contains each marker's end BB.  in getDelegateDepth()
1600   // fine, but delegate has to exactly target the correct try.  in getDelegateDepth()
1636       case WebAssembly::TRY:  in rewriteDepthImmediates()
1639                "Block/try marker should be balanced");  in rewriteDepthImmediates()
1713   // Place the BLOCK/LOOP/TRY markers to indicate the beginnings of scopes.  in runOnMachineFunction()
1716   // Remove unnecessary instructions possibly introduced by try/end_trys.  in runOnMachineFunction()
1724   // Fix up block/loop/try signatures at the end of the function to conform to  in runOnMachineFunction()