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      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_sj0", EHPersonality::GNU_CXX_SjLj)
     31     .Case("__gcc_personality_v0",  EHPersonality::GNU_C)
     32     .Case("__gcc_personality_sj0", EHPersonality::GNU_C_SjLj)
     33     .Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
     34     .Case("_except_handler3",      EHPersonality::MSVC_X86SEH)
     35     .Case("_except_handler4",      EHPersonality::MSVC_X86SEH)
     36     .Case("__C_specific_handler",  EHPersonality::MSVC_Win64SEH)
     37     .Case("__CxxFrameHandler3",    EHPersonality::MSVC_CXX)
     38     .Case("ProcessCLRException",   EHPersonality::CoreCLR)
     39     .Case("rust_eh_personality",   EHPersonality::Rust)
     40     .Default(EHPersonality::Unknown);
     41 }
     42 
     43 bool llvm::canSimplifyInvokeNoUnwind(const Function *F) {
     44   EHPersonality Personality = classifyEHPersonality(F->getPersonalityFn());
     45   // We can't simplify any invokes to nounwind functions if the personality
     46   // function wants to catch asynch exceptions.  The nounwind attribute only
     47   // implies that the function does not throw synchronous exceptions.
     48   return !isAsynchronousEHPersonality(Personality);
     49 }
     50 
     51 DenseMap<BasicBlock *, ColorVector> llvm::colorEHFunclets(Function &F) {
     52   SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
     53   BasicBlock *EntryBlock = &F.getEntryBlock();
     54   DenseMap<BasicBlock *, ColorVector> BlockColors;
     55 
     56   // Build up the color map, which maps each block to its set of 'colors'.
     57   // For any block B the "colors" of B are the set of funclets F (possibly
     58   // including a root "funclet" representing the main function) such that
     59   // F will need to directly contain B or a copy of B (where the term "directly
     60   // contain" is used to distinguish from being "transitively contained" in
     61   // a nested funclet).
     62   //
     63   // Note: Despite not being a funclet in the truest sense, a catchswitch is
     64   // considered to belong to its own funclet for the purposes of coloring.
     65 
     66   DEBUG_WITH_TYPE("winehprepare-coloring", dbgs() << "\nColoring funclets for "
     67                                                   << F.getName() << "\n");
     68 
     69   Worklist.push_back({EntryBlock, EntryBlock});
     70 
     71   while (!Worklist.empty()) {
     72     BasicBlock *Visiting;
     73     BasicBlock *Color;
     74     std::tie(Visiting, Color) = Worklist.pop_back_val();
     75     DEBUG_WITH_TYPE("winehprepare-coloring",
     76                     dbgs() << "Visiting " << Visiting->getName() << ", "
     77                            << Color->getName() << "\n");
     78     Instruction *VisitingHead = Visiting->getFirstNonPHI();
     79     if (VisitingHead->isEHPad()) {
     80       // Mark this funclet head as a member of itself.
     81       Color = Visiting;
     82     }
     83     // Note that this is a member of the given color.
     84     ColorVector &Colors = BlockColors[Visiting];
     85     if (std::find(Colors.begin(), Colors.end(), Color) == Colors.end())
     86       Colors.push_back(Color);
     87     else
     88       continue;
     89 
     90     DEBUG_WITH_TYPE("winehprepare-coloring",
     91                     dbgs() << "  Assigned color \'" << Color->getName()
     92                            << "\' to block \'" << Visiting->getName()
     93                            << "\'.\n");
     94 
     95     BasicBlock *SuccColor = Color;
     96     TerminatorInst *Terminator = Visiting->getTerminator();
     97     if (auto *CatchRet = dyn_cast<CatchReturnInst>(Terminator)) {
     98       Value *ParentPad = CatchRet->getCatchSwitchParentPad();
     99       if (isa<ConstantTokenNone>(ParentPad))
    100         SuccColor = EntryBlock;
    101       else
    102         SuccColor = cast<Instruction>(ParentPad)->getParent();
    103     }
    104 
    105     for (BasicBlock *Succ : successors(Visiting))
    106       Worklist.push_back({Succ, SuccColor});
    107   }
    108   return BlockColors;
    109 }
    110