lib/Analysis/EHPersonalities.cpp

   1 //===- EHPersonalities.cpp - Compute EH-related information ---------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/Analysis/EHPersonalities.h"
  11 #include "llvm/ADT/StringSwitch.h"
  12 #include "llvm/IR/CFG.h"
  13 #include "llvm/IR/Constants.h"
  14 #include "llvm/IR/Function.h"
  15 #include "llvm/IR/Instructions.h"
  16 #include "llvm/Support/Debug.h"
  17 #include "llvm/Support/raw_ostream.h"
  18 using namespace llvm;
  19
  20 /// See if the given exception handling personality function is one that we
  21 /// understand.  If so, return a description of it; otherwise return Unknown.
  22 EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
  23   const Function *F =
  24       Pers ? dyn_cast<Function>(Pers->stripPointerCasts()) : nullptr;
  25   if (!F)
  26     return EHPersonality::Unknown;
  27   return StringSwitch<EHPersonality>(F->getName())
  28     .Case("__gnat_eh_personality",     EHPersonality::GNU_Ada)
  29     .Case("__gxx_personality_v0",      EHPersonality::GNU_CXX)
  30     .Case("__gxx_personality_seh0",    EHPersonality::GNU_CXX)
  31     .Case("__gxx_personality_sj0",     EHPersonality::GNU_CXX_SjLj)
  32     .Case("__gcc_personality_v0",      EHPersonality::GNU_C)
  33     .Case("__gcc_personality_seh0",    EHPersonality::GNU_C)
  34     .Case("__gcc_personality_sj0",     EHPersonality::GNU_C_SjLj)
  35     .Case("__objc_personality_v0",     EHPersonality::GNU_ObjC)
  36     .Case("_except_handler3",          EHPersonality::MSVC_X86SEH)
  37     .Case("_except_handler4",          EHPersonality::MSVC_X86SEH)
  38     .Case("__C_specific_handler",      EHPersonality::MSVC_Win64SEH)
  39     .Case("__CxxFrameHandler3",        EHPersonality::MSVC_CXX)
  40     .Case("ProcessCLRException",       EHPersonality::CoreCLR)
  41     .Case("rust_eh_personality",       EHPersonality::Rust)
  42     .Case("__gxx_wasm_personality_v0", EHPersonality::Wasm_CXX)
  43     .Default(EHPersonality::Unknown);
  44 }
  45
  46 StringRef llvm::getEHPersonalityName(EHPersonality Pers) {
  47   switch (Pers) {
  48   case EHPersonality::GNU_Ada:       return "__gnat_eh_personality";
  49   case EHPersonality::GNU_CXX:       return "__gxx_personality_v0";
  50   case EHPersonality::GNU_CXX_SjLj:  return "__gxx_personality_sj0";
  51   case EHPersonality::GNU_C:         return "__gcc_personality_v0";
  52   case EHPersonality::GNU_C_SjLj:    return "__gcc_personality_sj0";
  53   case EHPersonality::GNU_ObjC:      return "__objc_personality_v0";
  54   case EHPersonality::MSVC_X86SEH:   return "_except_handler3";
  55   case EHPersonality::MSVC_Win64SEH: return "__C_specific_handler";
  56   case EHPersonality::MSVC_CXX:      return "__CxxFrameHandler3";
  57   case EHPersonality::CoreCLR:       return "ProcessCLRException";
  58   case EHPersonality::Rust:          return "rust_eh_personality";
  59   case EHPersonality::Wasm_CXX:      return "__gxx_wasm_personality_v0";
  60   case EHPersonality::Unknown:       llvm_unreachable("Unknown EHPersonality!");
  61   }
  62
  63   llvm_unreachable("Invalid EHPersonality!");
  64 }
  65
  66 EHPersonality llvm::getDefaultEHPersonality(const Triple &T) {
  67   return EHPersonality::GNU_C;
  68 }
  69
  70 bool llvm::canSimplifyInvokeNoUnwind(const Function *F) {
  71   EHPersonality Personality = classifyEHPersonality(F->getPersonalityFn());
  72   // We can't simplify any invokes to nounwind functions if the personality
  73   // function wants to catch asynch exceptions.  The nounwind attribute only
  74   // implies that the function does not throw synchronous exceptions.
  75   return !isAsynchronousEHPersonality(Personality);
  76 }
  77
  78 DenseMap<BasicBlock *, ColorVector> llvm::colorEHFunclets(Function &F) {
  79   SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
  80   BasicBlock *EntryBlock = &F.getEntryBlock();
  81   DenseMap<BasicBlock *, ColorVector> BlockColors;
  82
  83   // Build up the color map, which maps each block to its set of 'colors'.
  84   // For any block B the "colors" of B are the set of funclets F (possibly
  85   // including a root "funclet" representing the main function) such that
  86   // F will need to directly contain B or a copy of B (where the term "directly
  87   // contain" is used to distinguish from being "transitively contained" in
  88   // a nested funclet).
  89   //
  90   // Note: Despite not being a funclet in the truest sense, a catchswitch is
  91   // considered to belong to its own funclet for the purposes of coloring.
  92
  93   DEBUG_WITH_TYPE("winehprepare-coloring", dbgs() << "\nColoring funclets for "
  94                                                   << F.getName() << "\n");
  95
  96   Worklist.push_back({EntryBlock, EntryBlock});
  97
  98   while (!Worklist.empty()) {
  99     BasicBlock *Visiting;
 100     BasicBlock *Color;
 101     std::tie(Visiting, Color) = Worklist.pop_back_val();
 102     DEBUG_WITH_TYPE("winehprepare-coloring",
 103                     dbgs() << "Visiting " << Visiting->getName() << ", "
 104                            << Color->getName() << "\n");
 105     Instruction *VisitingHead = Visiting->getFirstNonPHI();
 106     if (VisitingHead->isEHPad()) {
 107       // Mark this funclet head as a member of itself.
 108       Color = Visiting;
 109     }
 110     // Note that this is a member of the given color.
 111     ColorVector &Colors = BlockColors[Visiting];
 112     if (!is_contained(Colors, Color))
 113       Colors.push_back(Color);
 114     else
 115       continue;
 116
 117     DEBUG_WITH_TYPE("winehprepare-coloring",
 118                     dbgs() << "  Assigned color \'" << Color->getName()
 119                            << "\' to block \'" << Visiting->getName()
 120                            << "\'.\n");
 121
 122     BasicBlock *SuccColor = Color;
 123     TerminatorInst *Terminator = Visiting->getTerminator();
 124     if (auto *CatchRet = dyn_cast<CatchReturnInst>(Terminator)) {
 125       Value *ParentPad = CatchRet->getCatchSwitchParentPad();
 126       if (isa<ConstantTokenNone>(ParentPad))
 127         SuccColor = EntryBlock;
 128       else
 129         SuccColor = cast<Instruction>(ParentPad)->getParent();
 130     }
 131
 132     for (BasicBlock *Succ : successors(Visiting))
 133       Worklist.push_back({Succ, SuccColor});
 134   }
 135   return BlockColors;
 136 }