From 9c9f5085e010059c813d2285ddff79b542c76834 Mon Sep 17 00:00:00 2001 From: Mark Rowe Date: Sun, 24 Nov 2024 14:18:25 -0800 Subject: [SharedCache] Optimize `ReadExportNode` `ReadExportNode` is called a lot during the initial load of the shared cache and thus impacts how long it takes for the UI to become responsive. This is a collection of optimizations that cut the time spent within `ReadExportNode` by 50%: 1. Pass iterators to `ReadExportNode` rather than a `DataBuffer` + offset. The lack of inlining in `DataBuffer`'s `operator[]` kills performance. Ideally this would have used `std::span`, but that would require bumping the minimum C++ version to C++20. 2. Add `MMappedFileAccessor::ReadSpan` so that `ReadExportNode` can operate directly on the mapped data without first copying it. 3. Removes a call to `GetAnalysisFunctionsForAddress` whose result was unused. 4. Use `std::find` to find the nul at the end of strings rather than assembling the string a character at a time. This avoids repeatedly growing the string. 5. Avoid the usual `Symbol` constructor in favor of `BNCreateSymbol`. The `Symbol` constructor has over head in two forms: 1. It has a `NameSpace` as an argument. Creating / destroying this allocates and deallocates memory We could create a single instance and reuse it for all calls, but... 2. The constructor copies all fields of the `NameSpace` to the heap before calling `BNCreateSymbol` and then deallocates them afterwards. This seems unnecessary, and adds a non-trivial amount of overhead. This can go back to directly constructing the `Symbol` once the constructors are improved. --- view/sharedcache/core/VM.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'view/sharedcache/core/VM.h') diff --git a/view/sharedcache/core/VM.h b/view/sharedcache/core/VM.h index 955dcbec..d567dce8 100644 --- a/view/sharedcache/core/VM.h +++ b/view/sharedcache/core/VM.h @@ -187,6 +187,14 @@ public: BinaryNinja::DataBuffer ReadBuffer(size_t addr, size_t length); + // Returns a range of pointers within the mapped memory region corresponding to + // {addr, length}. + // WARNING: The pointers returned by this method is only valid for the lifetime + // of this file accessor. + // TODO: This should use std::span once the minimum supported + // C++ version supports it. + std::pair ReadSpan(size_t addr, size_t length); + void Read(void *dest, size_t addr, size_t length); }; -- cgit v1.3.1