10b57cec5SDimitry Andric //===- EHStreamer.h - Exception Handling Directive Streamer -----*- C++ -*-===// 20b57cec5SDimitry Andric // 30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 60b57cec5SDimitry Andric // 70b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 80b57cec5SDimitry Andric // 90b57cec5SDimitry Andric // This file contains support for writing exception info into assembly files. 100b57cec5SDimitry Andric // 110b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 120b57cec5SDimitry Andric 130b57cec5SDimitry Andric #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H 140b57cec5SDimitry Andric #define LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H 150b57cec5SDimitry Andric 160b57cec5SDimitry Andric #include "llvm/ADT/DenseMap.h" 170b57cec5SDimitry Andric #include "llvm/CodeGen/AsmPrinterHandler.h" 180b57cec5SDimitry Andric #include "llvm/Support/Compiler.h" 190b57cec5SDimitry Andric 200b57cec5SDimitry Andric namespace llvm { 210b57cec5SDimitry Andric 220b57cec5SDimitry Andric class AsmPrinter; 230b57cec5SDimitry Andric struct LandingPadInfo; 240b57cec5SDimitry Andric class MachineInstr; 250b57cec5SDimitry Andric class MachineModuleInfo; 260b57cec5SDimitry Andric class MCSymbol; 270b57cec5SDimitry Andric template <typename T> class SmallVectorImpl; 280b57cec5SDimitry Andric 290b57cec5SDimitry Andric /// Emits exception handling directives. 300b57cec5SDimitry Andric class LLVM_LIBRARY_VISIBILITY EHStreamer : public AsmPrinterHandler { 310b57cec5SDimitry Andric protected: 320b57cec5SDimitry Andric /// Target of directive emission. 330b57cec5SDimitry Andric AsmPrinter *Asm; 340b57cec5SDimitry Andric 350b57cec5SDimitry Andric /// Collected machine module information. 360b57cec5SDimitry Andric MachineModuleInfo *MMI; 370b57cec5SDimitry Andric 380b57cec5SDimitry Andric /// How many leading type ids two landing pads have in common. 390b57cec5SDimitry Andric static unsigned sharedTypeIDs(const LandingPadInfo *L, 400b57cec5SDimitry Andric const LandingPadInfo *R); 410b57cec5SDimitry Andric 420b57cec5SDimitry Andric /// Structure holding a try-range and the associated landing pad. 430b57cec5SDimitry Andric struct PadRange { 440b57cec5SDimitry Andric // The index of the landing pad. 450b57cec5SDimitry Andric unsigned PadIndex; 460b57cec5SDimitry Andric 470b57cec5SDimitry Andric // The index of the begin and end labels in the landing pad's label lists. 480b57cec5SDimitry Andric unsigned RangeIndex; 490b57cec5SDimitry Andric }; 500b57cec5SDimitry Andric 510b57cec5SDimitry Andric using RangeMapType = DenseMap<MCSymbol *, PadRange>; 520b57cec5SDimitry Andric 530b57cec5SDimitry Andric /// Structure describing an entry in the actions table. 540b57cec5SDimitry Andric struct ActionEntry { 550b57cec5SDimitry Andric int ValueForTypeID; // The value to write - may not be equal to the type id. 560b57cec5SDimitry Andric int NextAction; 570b57cec5SDimitry Andric unsigned Previous; 580b57cec5SDimitry Andric }; 590b57cec5SDimitry Andric 600b57cec5SDimitry Andric /// Structure describing an entry in the call-site table. 610b57cec5SDimitry Andric struct CallSiteEntry { 620b57cec5SDimitry Andric // The 'try-range' is BeginLabel .. EndLabel. 630b57cec5SDimitry Andric MCSymbol *BeginLabel; // Null indicates the start of the function. 640b57cec5SDimitry Andric MCSymbol *EndLabel; // Null indicates the end of the function. 650b57cec5SDimitry Andric 660b57cec5SDimitry Andric // LPad contains the landing pad start labels. 670b57cec5SDimitry Andric const LandingPadInfo *LPad; // Null indicates that there is no landing pad. 680b57cec5SDimitry Andric 690b57cec5SDimitry Andric unsigned Action; 700b57cec5SDimitry Andric }; 710b57cec5SDimitry Andric 720b57cec5SDimitry Andric /// Structure describing a contiguous range of call-sites which reside 730b57cec5SDimitry Andric /// in the same procedure fragment. With -fbasic-block-sections, there will 740b57cec5SDimitry Andric /// be one call site range per basic block section. Otherwise, we will have 750b57cec5SDimitry Andric /// one call site range containing all the call sites in the function. 760b57cec5SDimitry Andric struct CallSiteRange { 770b57cec5SDimitry Andric // Symbol marking the beginning of the precedure fragment. 780b57cec5SDimitry Andric MCSymbol *FragmentBeginLabel = nullptr; 790b57cec5SDimitry Andric // Symbol marking the end of the procedure fragment. 800b57cec5SDimitry Andric MCSymbol *FragmentEndLabel = nullptr; 810b57cec5SDimitry Andric // LSDA symbol for this call-site range. 820b57cec5SDimitry Andric MCSymbol *ExceptionLabel = nullptr; 830b57cec5SDimitry Andric // Index of the first call-site entry in the call-site table which 840b57cec5SDimitry Andric // belongs to this range. 850b57cec5SDimitry Andric size_t CallSiteBeginIdx = 0; 860b57cec5SDimitry Andric // Index just after the last call-site entry in the call-site table which 870b57cec5SDimitry Andric // belongs to this range. 880b57cec5SDimitry Andric size_t CallSiteEndIdx = 0; 890b57cec5SDimitry Andric // Whether this is the call-site range containing all the landing pads. 900b57cec5SDimitry Andric bool IsLPRange = false; 910b57cec5SDimitry Andric }; 920b57cec5SDimitry Andric 930b57cec5SDimitry Andric /// Compute the actions table and gather the first action index for each 940b57cec5SDimitry Andric /// landing pad site. 950b57cec5SDimitry Andric void computeActionsTable( 960b57cec5SDimitry Andric const SmallVectorImpl<const LandingPadInfo *> &LandingPads, 970b57cec5SDimitry Andric SmallVectorImpl<ActionEntry> &Actions, 980b57cec5SDimitry Andric SmallVectorImpl<unsigned> &FirstActions); 990b57cec5SDimitry Andric 1000b57cec5SDimitry Andric void computePadMap(const SmallVectorImpl<const LandingPadInfo *> &LandingPads, 1010b57cec5SDimitry Andric RangeMapType &PadMap); 1020b57cec5SDimitry Andric 1030b57cec5SDimitry Andric /// Compute the call-site table and the call-site ranges. The entry for an 1040b57cec5SDimitry Andric /// invoke has a try-range containing the call, a non-zero landing pad and an 1050b57cec5SDimitry Andric /// appropriate action. The entry for an ordinary call has a try-range 1060b57cec5SDimitry Andric /// containing the call and zero for the landing pad and the action. Calls 1070b57cec5SDimitry Andric /// marked 'nounwind' have no entry and must not be contained in the try-range 1080b57cec5SDimitry Andric /// of any entry - they form gaps in the table. Entries must be ordered by 1090b57cec5SDimitry Andric /// try-range address. CallSiteRanges vector is only populated for Itanium 1100b57cec5SDimitry Andric /// exception handling. 1110b57cec5SDimitry Andric virtual void computeCallSiteTable( 1120b57cec5SDimitry Andric SmallVectorImpl<CallSiteEntry> &CallSites, 1130b57cec5SDimitry Andric SmallVectorImpl<CallSiteRange> &CallSiteRanges, 1140b57cec5SDimitry Andric const SmallVectorImpl<const LandingPadInfo *> &LandingPads, 1150b57cec5SDimitry Andric const SmallVectorImpl<unsigned> &FirstActions); 1160b57cec5SDimitry Andric 1170b57cec5SDimitry Andric /// Emit landing pads and actions. 1180b57cec5SDimitry Andric /// 1190b57cec5SDimitry Andric /// The general organization of the table is complex, but the basic concepts 1200b57cec5SDimitry Andric /// are easy. First there is a header which describes the location and 1210b57cec5SDimitry Andric /// organization of the three components that follow. 1220b57cec5SDimitry Andric /// 1. The landing pad site information describes the range of code covered 1230b57cec5SDimitry Andric /// by the try. In our case it's an accumulation of the ranges covered 1240b57cec5SDimitry Andric /// by the invokes in the try. There is also a reference to the landing 1250b57cec5SDimitry Andric /// pad that handles the exception once processed. Finally an index into 1260b57cec5SDimitry Andric /// the actions table. 1270b57cec5SDimitry Andric /// 2. The action table, in our case, is composed of pairs of type ids 1280b57cec5SDimitry Andric /// and next action offset. Starting with the action index from the 1290b57cec5SDimitry Andric /// landing pad site, each type Id is checked for a match to the current 1300b57cec5SDimitry Andric /// exception. If it matches then the exception and type id are passed 1310b57cec5SDimitry Andric /// on to the landing pad. Otherwise the next action is looked up. This 1320b57cec5SDimitry Andric /// chain is terminated with a next action of zero. If no type id is 1330b57cec5SDimitry Andric /// found the frame is unwound and handling continues. 1340b57cec5SDimitry Andric /// 3. Type id table contains references to all the C++ typeinfo for all 1350b57cec5SDimitry Andric /// catches in the function. This tables is reversed indexed base 1. 1360b57cec5SDimitry Andric /// 1370b57cec5SDimitry Andric /// Returns the starting symbol of an exception table. 1380b57cec5SDimitry Andric MCSymbol *emitExceptionTable(); 1390b57cec5SDimitry Andric 1400b57cec5SDimitry Andric virtual void emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel); 141 142 // Helpers for identifying what kind of clause an EH typeid or selector 143 // corresponds to. Negative selectors are for filter clauses, the zero 144 // selector is for cleanups, and positive selectors are for catch clauses. isFilterEHSelector(int Selector)145 static bool isFilterEHSelector(int Selector) { return Selector < 0; } isCleanupEHSelector(int Selector)146 static bool isCleanupEHSelector(int Selector) { return Selector == 0; } isCatchEHSelector(int Selector)147 static bool isCatchEHSelector(int Selector) { return Selector > 0; } 148 149 public: 150 EHStreamer(AsmPrinter *A); 151 ~EHStreamer() override; 152 153 // Unused. setSymbolSize(const MCSymbol * Sym,uint64_t Size)154 void setSymbolSize(const MCSymbol *Sym, uint64_t Size) override {} beginInstruction(const MachineInstr * MI)155 void beginInstruction(const MachineInstr *MI) override {} endInstruction()156 void endInstruction() override {} 157 158 /// Return `true' if this is a call to a function marked `nounwind'. Return 159 /// `false' otherwise. 160 static bool callToNoUnwindFunction(const MachineInstr *MI); 161 }; 162 163 } // end namespace llvm 164 165 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H 166