some docs

Author: Hardcode84

docs/dynamic_compile_bind.md

@@ -0,0 +1,25 @@
+# Dynamic compile bind
+
+## D part
+
+* bind function returns `BindPtr` object which is reference counted internally
+* `BindPtr` have `opCall` and `toDelegate` methods to call directly or create D delegate
+* On creation `BindPtr` call `void registerBindPayload(void* handle, void* originalFunc, void* exampleFunc, const ParamSlice* params, size_t paramsSize)` function
+    * `handle` - pointer to pointer to function, which uniquely identifies bind object, actual function pointer to generated code will be written here during `compileDynamicCode` call.
+    * `originalFunc` - pointer to `original` function, this is special function, generated inside `bind`, which just forwards parameter to user function or delegate, this function always have `@dynamicCompileEmit` attribute, so jit runtime will fins it even if user function wasn't marked `@dynamicCompile`
+    * `exampleFunc` - special function with parameters matched to original user function, runtime will extracts parameters types from it, never called
+    * `params` - list of slices to bind parameters, will be null for placeholders
+    * `paramsSize` - items count in `params`
+* On destruction `BindPtr` call `void unregisterBindPayload(void* handle);`
+    * `handle` - same handle as passed in `registerBindPayload` previously
+
+## Runtime part
+
+* `registerBindPayload` add handle to internal list
+* During `compileDynamicCode`
+    * `generateBind` - Generate new function for each bind handle
+        * Parse each bind parameter into llvm constant using existing `parseInitializer` (previously used for `@dynamicCompileConst`)
+        * If parameter is function pointer from another bind handle, replace with direct reference to that function
+        * Generate call to original function (this call will be inlined)
+    * Generate and optimize module as usual
+    * `applyBind` - update handles to generated code