llvm-6502/lib/Analysis/LibCallSemantics.cpp
Reid Kleckner 690248bf52 Don't promote asynch EH invokes of nounwind functions to calls
If the landingpad of the invoke is using a personality function that
catches asynch exceptions, then it can catch a trap.

Also add some landingpads to invalid LLVM IR test cases that lack them.

Over-the-shoulder reviewed by David Majnemer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228782 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 01:23:16 +00:00

103 lines
3.8 KiB
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//===- LibCallSemantics.cpp - Describe library semantics ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements interfaces that can be used to describe language
// specific runtime library interfaces (e.g. libc, libm, etc) to LLVM
// optimizers.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/IR/Function.h"
using namespace llvm;
/// This impl pointer in ~LibCallInfo is actually a StringMap. This
/// helper does the cast.
static StringMap<const LibCallFunctionInfo*> *getMap(void *Ptr) {
return static_cast<StringMap<const LibCallFunctionInfo*> *>(Ptr);
}
LibCallInfo::~LibCallInfo() {
delete getMap(Impl);
}
const LibCallLocationInfo &LibCallInfo::getLocationInfo(unsigned LocID) const {
// Get location info on the first call.
if (NumLocations == 0)
NumLocations = getLocationInfo(Locations);
assert(LocID < NumLocations && "Invalid location ID!");
return Locations[LocID];
}
/// Return the LibCallFunctionInfo object corresponding to
/// the specified function if we have it. If not, return null.
const LibCallFunctionInfo *
LibCallInfo::getFunctionInfo(const Function *F) const {
StringMap<const LibCallFunctionInfo*> *Map = getMap(Impl);
/// If this is the first time we are querying for this info, lazily construct
/// the StringMap to index it.
if (!Map) {
Impl = Map = new StringMap<const LibCallFunctionInfo*>();
const LibCallFunctionInfo *Array = getFunctionInfoArray();
if (!Array) return nullptr;
// We now have the array of entries. Populate the StringMap.
for (unsigned i = 0; Array[i].Name; ++i)
(*Map)[Array[i].Name] = Array+i;
}
// Look up this function in the string map.
return Map->lookup(F->getName());
}
/// See if the given exception handling personality function is one that we
/// understand. If so, return a description of it; otherwise return Unknown.
EHPersonality llvm::classifyEHPersonality(Value *Pers) {
Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
if (!F)
return EHPersonality::Unknown;
return StringSwitch<EHPersonality>(F->getName())
.Case("__gnat_eh_personality", EHPersonality::GNU_Ada)
.Case("__gxx_personality_v0", EHPersonality::GNU_CXX)
.Case("__gcc_personality_v0", EHPersonality::GNU_C)
.Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
.Case("__except_handler3", EHPersonality::MSVC_X86SEH)
.Case("__except_handler4", EHPersonality::MSVC_X86SEH)
.Case("__C_specific_handler", EHPersonality::MSVC_Win64SEH)
.Case("__CxxFrameHandler3", EHPersonality::MSVC_CXX)
.Default(EHPersonality::Unknown);
}
bool llvm::isAsynchronousEHPersonality(EHPersonality Pers) {
// The two SEH personality functions can catch asynch exceptions. We assume
// unknown personalities don't catch asynch exceptions.
switch (Pers) {
case EHPersonality::MSVC_X86SEH:
case EHPersonality::MSVC_Win64SEH:
return true;
default: return false;
}
llvm_unreachable("invalid enum");
}
bool llvm::canSimplifyInvokeNoUnwind(const InvokeInst *II) {
const LandingPadInst *LP = II->getLandingPadInst();
EHPersonality Personality = classifyEHPersonality(LP->getPersonalityFn());
// We can't simplify any invokes to nounwind functions if the personality
// function wants to catch asynch exceptions. The nounwind attribute only
// implies that the function does not throw synchronous exceptions.
return !isAsynchronousEHPersonality(Personality);
}