en Copyright 2015 Java http://172.16.0.5:8080/history/wasmtime-44.0.1/crates/wizer/examples/cpp/Makefile#1dc5bf02 Makefile changes for newer clang List of files: /wasmtime-44.0.1/crates/wizer/examples/cpp/Makefile Thu, 15 Dec 2022 00:21:48 +0000 Trevor Elliott <telliott@fastly.com> http://172.16.0.5:8080/history/wasmtime-44.0.1/crates/wizer/examples/cpp/Makefile#9ab84eea Add C++ example using function renaming to handle ctors properly.Previously, it was difficult to properly use Wizer with C++ programsthat have static constructors. These constructors are normally runbefore `main()` is invoked by some libc/linker plumbing at the usualentry point. This causes a set of undesirable problems:- In the Wizer initialization entry point, our globals' constructors have not yet run.- If we manually invoke the constructors to resolve the first issue, then they will be *re*-invoked when the program's main entry point is run on the initialized module. This may cause surprising or inconsistent results.In order to properly handle this, we add a `wizer.h` header with aconvenient macro that allows specifying a user initialization function,and adds an exported top-level Wizer initialization entry point and anexported replacement main entry point.The generated initialization entry point invokes any global constructors(using the function `__wasm_call_ctors()` which is generated by`wasm-ld`) then invokes the user's initialization function.The generated main entry point is meant to replace `_start` and performsthe same work, *except* that it does not re-invoke constructors.Instead, it immediately invokes `main()` (because everything has alreadybeen initialized) and then calls destructors and exits.Taken together, the two entry points match the code that is present in`_start` in an ordinary Wasm binary compiled by wasi-sdk. This approachshould be relatively stable, as long as the symbols`__wasm_call_ctors()`, `__wasm_call_dtors()`, and `__original_main()`are not renamed in the WASI SDK (this seems unlikely). List of files: /wasmtime-44.0.1/crates/wizer/examples/cpp/Makefile Wed, 10 Feb 2021 06:35:30 +0000 Chris Fallin <chris@cfallin.org>