Function allocate

src/e9patch/e9alloc.cpp:561–592

* Allocates a chunk of virtual address space of size `size` and within the * range [lb..ub]. Returns the allocation, or nullptr on failure. */

 * range [lb..ub].  Returns the allocation, or nullptr on failure.
 */
const Alloc *allocate(Binary *B, intptr_t lb, intptr_t ub,
    const Trampoline *T, const Instr *I, bool same_page)
{
    Allocator &allocator = B->allocator;
    if (!verify(lb, ub + TRAMPOLINE_MAX))
        return nullptr;
    int presize = getTrampolinePrologueSize(B, I);
    int tmpsize = getTrampolineSize(B, T, I);
    if (tmpsize < 0)
        return nullptr;
    lb -= (intptr_t)presize;
    ub += (intptr_t)tmpsize;
    size_t size = (size_t)presize + (size_t)tmpsize;
    uint32_t flags = (same_page? FLAG_SAME_PAGE: 0);
    Node *n = nullptr;
    const intptr_t target = 0x70C00000;
    if (option_Oorder && ub > target)
        n = insert(allocator.tree.root, lb, target, size, flags | FLAG_RIGHT);
    if (n == nullptr)
        n = insert(allocator.tree.root, lb, ub, size, flags);
    if (n == nullptr)
        return nullptr;
    if (allocator.tree.root == nullptr)
        allocator.tree.root = n;
    rebalanceInsert(&allocator.tree, n);

    Alloc *A = &n->alloc;
    A->T     = T;
    A->I     = I;
    A->entry = (unsigned)presize;
    return A;
}

/*
 * Reserves a chunk of the virtual address space spanning the range [lb..ub].