lib/Analysis/LibCallSemantics.cpp

   1 //===- LibCallSemantics.cpp - Describe library semantics ------------------===//
   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 // This file implements interfaces that can be used to describe language
  11 // specific runtime library interfaces (e.g. libc, libm, etc) to LLVM
  12 // optimizers.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/Analysis/LibCallSemantics.h"
  17 #include "llvm/ADT/StringSwitch.h"
  18 #include "llvm/IR/Function.h"
  19 using namespace llvm;
  20
  21 /// See if the given exception handling personality function is one that we
  22 /// understand.  If so, return a description of it; otherwise return Unknown.
  23 EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
  24   const Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
  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     .Default(EHPersonality::Unknown);
  37 }
  38
  39 bool llvm::canSimplifyInvokeNoUnwind(const Function *F) {
  40   EHPersonality Personality = classifyEHPersonality(F->getPersonalityFn());
  41   // We can't simplify any invokes to nounwind functions if the personality
  42   // function wants to catch asynch exceptions.  The nounwind attribute only
  43   // implies that the function does not throw synchronous exceptions.
  44   return !isAsynchronousEHPersonality(Personality);
  45 }