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//===- BlockVerifier.cpp - FDR Block Verifier -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/XRay/BlockVerifier.h"
#include "llvm/Support/Error.h"
#include <bitset>
namespace llvm {
namespace xray {
namespace {
constexpr unsigned long long mask(BlockVerifier::State S) {
return 1uLL << static_cast<std::size_t>(S);
}
constexpr std::size_t number(BlockVerifier::State S) {
return static_cast<std::size_t>(S);
}
StringRef recordToString(BlockVerifier::State R) {
switch (R) {
case BlockVerifier::State::BufferExtents:
return "BufferExtents";
case BlockVerifier::State::NewBuffer:
return "NewBuffer";
case BlockVerifier::State::WallClockTime:
return "WallClockTime";
case BlockVerifier::State::PIDEntry:
return "PIDEntry";
case BlockVerifier::State::NewCPUId:
return "NewCPUId";
case BlockVerifier::State::TSCWrap:
return "TSCWrap";
case BlockVerifier::State::CustomEvent:
return "CustomEvent";
case BlockVerifier::State::Function:
return "Function";
case BlockVerifier::State::CallArg:
return "CallArg";
case BlockVerifier::State::EndOfBuffer:
return "EndOfBuffer";
case BlockVerifier::State::TypedEvent:
return "TypedEvent";
case BlockVerifier::State::StateMax:
case BlockVerifier::State::Unknown:
return "Unknown";
}
llvm_unreachable("Unkown state!");
}
struct Transition {
BlockVerifier::State From;
std::bitset<number(BlockVerifier::State::StateMax)> ToStates;
};
} // namespace
Error BlockVerifier::transition(State To) {
using ToSet = std::bitset<number(State::StateMax)>;
static constexpr std::array<const Transition, number(State::StateMax)>
TransitionTable{{{State::Unknown,
{mask(State::BufferExtents) | mask(State::NewBuffer)}},
{State::BufferExtents, {mask(State::NewBuffer)}},
{State::NewBuffer, {mask(State::WallClockTime)}},
{State::WallClockTime,
{mask(State::PIDEntry) | mask(State::NewCPUId)}},
{State::PIDEntry, {mask(State::NewCPUId)}},
{State::NewCPUId,
{mask(State::NewCPUId) | mask(State::TSCWrap) |
mask(State::CustomEvent) | mask(State::Function) |
mask(State::EndOfBuffer) | mask(State::TypedEvent)}},
{State::TSCWrap,
{mask(State::TSCWrap) | mask(State::NewCPUId) |
mask(State::CustomEvent) | mask(State::Function) |
mask(State::EndOfBuffer) | mask(State::TypedEvent)}},
{State::CustomEvent,
{mask(State::CustomEvent) | mask(State::TSCWrap) |
mask(State::NewCPUId) | mask(State::Function) |
mask(State::EndOfBuffer) | mask(State::TypedEvent)}},
{State::TypedEvent,
{mask(State::TypedEvent) | mask(State::TSCWrap) |
mask(State::NewCPUId) | mask(State::Function) |
mask(State::EndOfBuffer) | mask(State::CustomEvent)}},
{State::Function,
{mask(State::Function) | mask(State::TSCWrap) |
mask(State::NewCPUId) | mask(State::CustomEvent) |
mask(State::CallArg) | mask(State::EndOfBuffer) |
mask(State::TypedEvent)}},
{State::CallArg,
{mask(State::CallArg) | mask(State::Function) |
mask(State::TSCWrap) | mask(State::NewCPUId) |
mask(State::CustomEvent) | mask(State::EndOfBuffer) |
mask(State::TypedEvent)}},
{State::EndOfBuffer, {}}}};
if (CurrentRecord >= State::StateMax)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"BUG (BlockVerifier): Cannot find transition table entry for %s, "
"transitioning to %s.",
recordToString(CurrentRecord).data(), recordToString(To).data());
// If we're at an EndOfBuffer record, we ignore anything that follows that
// isn't a NewBuffer record.
if (CurrentRecord == State::EndOfBuffer && To != State::NewBuffer)
return Error::success();
auto &Mapping = TransitionTable[number(CurrentRecord)];
auto &Destinations = Mapping.ToStates;
assert(Mapping.From == CurrentRecord &&
"BUG: Wrong index for record mapping.");
if ((Destinations & ToSet(mask(To))) == 0)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"BlockVerifier: Invalid transition from %s to %s.",
recordToString(CurrentRecord).data(), recordToString(To).data());
CurrentRecord = To;
return Error::success();
} // namespace xray
Error BlockVerifier::visit(BufferExtents &) {
return transition(State::BufferExtents);
}
Error BlockVerifier::visit(WallclockRecord &) {
return transition(State::WallClockTime);
}
Error BlockVerifier::visit(NewCPUIDRecord &) {
return transition(State::NewCPUId);
}
Error BlockVerifier::visit(TSCWrapRecord &) {
return transition(State::TSCWrap);
}
Error BlockVerifier::visit(CustomEventRecord &) {
return transition(State::CustomEvent);
}
Error BlockVerifier::visit(CustomEventRecordV5 &) {
return transition(State::CustomEvent);
}
Error BlockVerifier::visit(TypedEventRecord &) {
return transition(State::TypedEvent);
}
Error BlockVerifier::visit(CallArgRecord &) {
return transition(State::CallArg);
}
Error BlockVerifier::visit(PIDRecord &) { return transition(State::PIDEntry); }
Error BlockVerifier::visit(NewBufferRecord &) {
return transition(State::NewBuffer);
}
Error BlockVerifier::visit(EndBufferRecord &) {
return transition(State::EndOfBuffer);
}
Error BlockVerifier::visit(FunctionRecord &) {
return transition(State::Function);
}
Error BlockVerifier::verify() {
// The known terminal conditions are the following:
switch (CurrentRecord) {
case State::EndOfBuffer:
case State::NewCPUId:
case State::CustomEvent:
case State::TypedEvent:
case State::Function:
case State::CallArg:
case State::TSCWrap:
return Error::success();
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"BlockVerifier: Invalid terminal condition %s, malformed block.",
recordToString(CurrentRecord).data());
}
}
void BlockVerifier::reset() { CurrentRecord = State::Unknown; }
} // namespace xray
} // namespace llvm
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