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"
18using 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.
22EHPersonality 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
40bool 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
48DenseMap<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}
107