systems 4About Me Other interests: Game engines Meta-programming 5Robot path planning 6Robot path planning Path planning 7Path planning How an (autonomous) agent figures out how to get from one location 28High level goals of this talk Implement cache-friendly path planning code in C++ 29High level goals of this talk Implement cache-friendly path planning code in C++ Do so using the STL 30High level talk Implement cache-friendly path planning code in C++ Do so using the STL Try to keep our choices simple 31High level goals of this talk Implement cache-friendly path planning code in C++ Do so using

Finding Bugs using Path-Sensitive Static Analysis Gábor Horváth Gabor.Horvath@microsoft.com @XazaxHunWelcome to CppCon 2021! Join #visual_studio channel on CppCon Discord https://aka.ms/cppcon/discord the latest announcements Take our survey https://aka.ms/cppconAgenda • Intro to path-sensitive static analysis • Path-sensitive checks in MSVC • A look under the hood • Upcoming features • Lessons taking branch 3 • All warnings on infeasible paths are noise • Need info on the whole state! void path_sensitive(int *p, bool cond) { int var = 0; // branch 1 if (p != nullptr) { var =

occupancy map at all times ● Solution: The robot will send a request to a ROS 2 service that generates a path from the robot’s current location and goal location, given an occupancy map Clip from https://www PathGenerator( rclcpp::NodeOptions const& options = rclcpp::NodeOptions{}) : Node("path_generator", options); private: void set_map_service( const std::shared_ptr equest> request, std::shared_ptr response); void generate_path_service( const std::shared_ptr request, std::shared_ptr

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during a semantic analysis of the code in which it appears. It is never an l-value and never has side effects. Constant expressions are not limited to the capabilities of semantic analysis, such as constant variables previously declared macros and templates previously declared procedures that have no side effects beyond possibly modifying compile-time variables A constant expression can contain code blocks that new scope. Discard statement Example: The discard statement evaluates its expression for side-effects and throws the expression's resulting value away, and should only be used when ignoring this value

@intFromPtr C Pointers volatile Loads and stores are assumed to not have side effects. If a given load or store should have side effects, such as Memory Mapped Input/Output (MMIO), use volatile . In the following to an unconditional defer, Zig has errdefer , which evaluates the deferred expression on block exit path if and only if the function returned with an error from the block. Example: errdefer_example.zig robust error handling without the verbosity and cognitive overhead of trying to make sure every exit path is covered. The deallocation code is always directly following the allocation code. Common errdefer

Zero Bit Types volatile Loads and stores are assumed to not have side effects. If a given load or store should have side effects, such as Memory Mapped Input/Output (MMIO), use volatile. In the following to an unconditional defer, Zig has errdefer, which evaluates the deferred expression on block exit path if and only if the function returned with an error from the block. Example: fn createFoo(param: robust error handling without the verbosity and cognitive overhead of trying to make sure every exit path is covered. The deallocation code is always directly following the allocation code. A couple of other

Per-field atomics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 24.7 Side effects and mutable function arguments . . . . . . . . . . . . . . . . . . . . . 307CONTENTS v 24.8 @threadcall undefined. It is strongly recommended not to use expressions with side effects (such as printing) in chained comparisons. If side effects are required, the short-circuit && operator should be used explicitly Returning nothing For functions that do not need to return a value (functions used only for some side effects), the Julia convention is to return the value nothing: function printx(x) println("x = $x") return

Per-field atomics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 24.7 Side effects and mutable function arguments . . . . . . . . . . . . . . . . . . . . . 307CONTENTS v 24.8 @threadcall undefined. It is strongly recommended not to use expressions with side effects (such as printing) in chained comparisons. If side effects are required, the short-circuit && operator should be used explicitly Returning nothing For functions that do not need to return a value (functions used only for some side effects), the Julia convention is to return the value nothing: function printx(x) println("x = $x") return

Per-field atomics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 24.7 Side effects and mutable function arguments . . . . . . . . . . . . . . . . . . . . . 304 24.8 @threadcall . undefined. It is strongly recommended not to use expressions with side effects (such as printing) in chained comparisons. If side effects are required, the short-circuit && operator should be used explicitly Returning nothing For functions that do not need to return a value (functions used only for some side effects), the Julia convention is to return the value nothing: function printx(x) println("x = $x") return

Per-field atomics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 24.7 Side effects and mutable function arguments . . . . . . . . . . . . . . . . . . . . . 304 24.8 @threadcall . undefined. It is strongly recommended not to use expressions with side effects (such as printing) in chained comparisons. If side effects are required, the short-circuit && operator should be used explicitly Returning nothing For functions that do not need to return a value (functions used only for some side effects), the Julia convention is to return the value nothing: function printx(x) println("x = $x") return