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("__gcc_personality_v0",  EHPersonality::GNU_C)
  31     .Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
  32     .Case("_except_handler3",      EHPersonality::MSVC_X86SEH)
  33     .Case("_except_handler4",      EHPersonality::MSVC_X86SEH)
  34     .Case("__C_specific_handler",  EHPersonality::MSVC_Win64SEH)
  35     .Case("__CxxFrameHandler3",    EHPersonality::MSVC_CXX)
  36     .Case("ProcessCLRException",   EHPersonality::CoreCLR)
  37     .Default(EHPersonality::Unknown);
  38 }
  39
  40 bool llvm::canSimplifyInvokeNoUnwind(const Function *F) {
  41   EHPersonality Personality = classifyEHPersonality(F->getPersonalityFn());
  42   // We can't simplify any invokes to nounwind functions if the personality
  43   // function wants to catch asynch exceptions.  The nounwind attribute only
  44   // implies that the function does not throw synchronous exceptions.
  45   return !isAsynchronousEHPersonality(Personality);
  46 }
  47
  48 DenseMap<BasicBlock *, ColorVector> llvm::colorEHFunclets(Function &F) {
  49   SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
  50   BasicBlock *EntryBlock = &F.getEntryBlock();
  51   DenseMap<BasicBlock *, ColorVector> BlockColors;
  52
  53   // Build up the color map, which maps each block to its set of 'colors'.
  54   // For any block B the "colors" of B are the set of funclets F (possibly
  55   // including a root "funclet" representing the main function) such that
  56   // F will need to directly contain B or a copy of B (where the term "directly
  57   // contain" is used to distinguish from being "transitively contained" in
  58   // a nested funclet).
  59   //
  60   // Note: Despite not being a funclet in the truest sense, a catchswitch is
  61   // considered to belong to its own funclet for the purposes of coloring.
  62
  63   DEBUG_WITH_TYPE("winehprepare-coloring", dbgs() << "\nColoring funclets for "
  64                                                   << F.getName() << "\n");
  65
  66   Worklist.push_back({EntryBlock, EntryBlock});
  67
  68   while (!Worklist.empty()) {
  69     BasicBlock *Visiting;
  70     BasicBlock *Color;
  71     std::tie(Visiting, Color) = Worklist.pop_back_val();
  72     DEBUG_WITH_TYPE("winehprepare-coloring",
  73                     dbgs() << "Visiting " << Visiting->getName() << ", "
  74                            << Color->getName() << "\n");
  75     Instruction *VisitingHead = Visiting->getFirstNonPHI();
  76     if (VisitingHead->isEHPad()) {
  77       // Mark this funclet head as a member of itself.
  78       Color = Visiting;
  79     }
  80     // Note that this is a member of the given color.
  81     ColorVector &Colors = BlockColors[Visiting];
  82     if (std::find(Colors.begin(), Colors.end(), Color) == Colors.end())
  83       Colors.push_back(Color);
  84     else
  85       continue;
  86
  87     DEBUG_WITH_TYPE("winehprepare-coloring",
  88                     dbgs() << "  Assigned color \'" << Color->getName()
  89                            << "\' to block \'" << Visiting->getName()
  90                            << "\'.\n");
  91
  92     BasicBlock *SuccColor = Color;
  93     TerminatorInst *Terminator = Visiting->getTerminator();
  94     if (auto *CatchRet = dyn_cast<CatchReturnInst>(Terminator)) {
  95       Value *ParentPad = CatchRet->getParentPad();
  96       if (isa<ConstantTokenNone>(ParentPad))
  97         SuccColor = EntryBlock;
  98       else
  99         SuccColor = cast<Instruction>(ParentPad)->getParent();
 100     }
 101
 102     for (BasicBlock *Succ : successors(Visiting))
 103       Worklist.push_back({Succ, SuccColor});
 104   }
 105   return BlockColors;
 106 }