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Title: Auto-deref map access in assignments and Add Forward Declarations by SiyuanSun0736 · Pull Request #14 · multikernel/kernelscript · GitHub

Open Graph Title: Auto-deref map access in assignments and Add Forward Declarations by SiyuanSun0736 · Pull Request #14 · multikernel/kernelscript

X Title: Auto-deref map access in assignments and Add Forward Declarations by SiyuanSun0736 · Pull Request #14 · multikernel/kernelscript

Description: Overview This PR resolves a type mismatch bug in eBPF C code generation and improves the robustness of userspace code generation. The primary fix ensures that map lookups on the right-hand side of assignment statements follow KernelScript's value semantics rather than returning raw pointers. Key Changes 1. eBPF C Codegen: Assignment Value Semantics Target: src/ebpf_c_codegen.ml Change: Modified generate_assignment to use auto_deref_map_access:true when the source value is an IRMapAccess. Logic: Previously, while variable declarations (e.g., var x = map[k]) correctly generated dereferencing logic, standard assignments (e.g., x = map[k]) were incorrectly assigning the bpf_map_lookup_elem pointer directly to a value-type variable. 2. Userspace Codegen: Forward Declarations Target: src/userspace_codegen.ml Change: Added logic to generate forward declarations for ring buffer callback handlers (e.g., int ( *event);). Logic: Prevents implicit declaration errors and order-of-definition issues in the generated userspace C code, especially when dispatch_used is true. Code Comparison (eBPF C) Before Assigning a pointer type (struct Stats *) to a value type (struct Stats) caused a compilation error. struct Stats* __map_lookup_3; // ... (lookup logic) stat = __map_lookup_3; // Error: incompatible type After The assignment now generates a safe dereferencing block with a NULL check. struct Stats* __map_lookup_3; // ... (lookup logic) stat = ({ struct Stats __val = {0}; if (__map_lookup_3) { __val = *(__map_lookup_3); } __val; }); Impact & Rationale Type Safety: Enforces consistent behavior across all map access contexts (initialization vs. assignment). Correctness: Fixes the incompatible type error observed in examples/ringbuf_demo. Code Standards: Generated userspace code now includes necessary prototypes for callbacks.

Open Graph Description: Overview This PR resolves a type mismatch bug in eBPF C code generation and improves the robustness of userspace code generation. The primary fix ensures that map lookups on the right-hand side of ...

X Description: Overview This PR resolves a type mismatch bug in eBPF C code generation and improves the robustness of userspace code generation. The primary fix ensures that map lookups on the right-hand side of ...

Opengraph URL: https://github.com/multikernel/kernelscript/pull/14

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