Trait McjitMemoryManager 

pub trait McjitMemoryManager: Debug {
    // Required methods
    fn allocate_code_section(
        &mut self,
        size: uintptr_t,
        alignment: c_uint,
        section_id: c_uint,
        section_name: &str,
    ) -> *mut u8;
    fn allocate_data_section(
        &mut self,
        size: uintptr_t,
        alignment: c_uint,
        section_id: c_uint,
        section_name: &str,
        is_read_only: bool,
    ) -> *mut u8;
    fn finalize_memory(&mut self) -> Result<(), String>;
    fn destroy(&mut self);
}

A trait for user-defined memory management in MCJIT.

Implementors can override how LLVM’s MCJIT engine allocates memory for code and data sections. This is sometimes needed for:

• custom allocators,
• sandboxed or restricted environments,
• capturing stack map sections (e.g., for garbage collection),
• or other specialized JIT memory management requirements.

StackMap and GC Integration

By examining the section_name argument in McjitMemoryManager::allocate_data_section, you can detect sections such as .llvm_stackmaps (on ELF) or __llvm_stackmaps (on Mach-O). Recording the location of these sections may be useful for custom garbage collectors. For more information, refer to the LLVM StackMaps documentation.

Typically, on Darwin (Mach-O), the stack map section name is __llvm_stackmaps, and on Linux (ELF), it is .llvm_stackmaps.

Required Methods

fn allocate_code_section( &mut self, size: uintptr_t, alignment: c_uint, section_id: c_uint, section_name: &str, ) -> *mut u8

Allocates a block of memory for a code section.

Parameters

• size - The size in bytes for the code section.
• alignment - The required alignment in bytes.
• section_id - A numeric ID that LLVM uses to identify this section.
• section_name - A name for this section, if provided by LLVM.

Returns

Returns a pointer to the allocated memory. Implementors must ensure it is at least size bytes long and meets alignment requirements.

fn allocate_data_section( &mut self, size: uintptr_t, alignment: c_uint, section_id: c_uint, section_name: &str, is_read_only: bool, ) -> *mut u8

Allocates a block of memory for a data section.

Parameters

• size - The size in bytes for the data section.
• alignment - The required alignment in bytes.
• section_id - A numeric ID that LLVM uses to identify this section.
• section_name - A name for this section, if provided by LLVM.
• is_read_only - Whether this data section should be read-only.

Returns

Returns a pointer to the allocated memory. Implementors must ensure it is at least size bytes long and meets alignment requirements.

fn finalize_memory(&mut self) -> Result<(), String>

Finalizes memory permissions for all allocated sections.

This is called once all sections have been allocated. Implementors can set permissions such as making code sections executable or data sections read-only.

Errors

If any error occurs (for example, failing to set page permissions), return an Err(String). This error is reported back to LLVM as a C string.

fn destroy(&mut self)

Cleans up or deallocates resources before the memory manager is destroyed.

This is called when LLVM has finished using the memory manager. Any additional allocations or references should be released here if needed.

Implementors