It is only support amd64+Linux.
- at the beginning of
cg_invoke
.L2:
push %rbp
movq %rsp, %rbp
push %rbx
push %r12
push %r13
push %r14
push %r15
push %rsi
push %rdi
the stack is like below
+--------------------------+
| rdi |
| rsi |
| r15 |
| r14 |
| r13 |
| r12 |
| rbx |
| rbp |
| return address of `main` | in `cg_invoke`
|--------------------------|
| frame of `main` |
| ... | in `main`
| ... |
rbp, rbx, r12, r13, r14, and r15 are callee saved
registered. These are the environment must be saved so that cg_yield
could rewind the stack, and return directly to main.
rdi is the struct cg_t * co, which is used to save the stack of
the generator.
rsi is the return value of cg_yield, save it anyway.
- restore the stack
movq (%rdi),%rdx /* stack size in byte */
subq %rdx, %rsp /* alloc stack */
movq $0x1, 0x10(%rdi) /* this->is_done = 1 */
/* restore stack */
movq 0x8(%rdi), %rsi /* this->stack, read */
movq %rsp, %rdi /* dst */
call memcpy
after memcpy, the stack is as below
+--------------------------+
a ->| rdi |
| rsi |
| r15 |
| r14 |
| r13 |
| r12 |
| rbx |
| rbp |
| return address | in `cg_return`
|--------------------------|
| variable size of space |
| for the generator |
b ->| return address | in `generator`
|--------------------------|
| rdi |
| rsi |
| r15 |
| r14 |
| r13 |
| r12 |
| rbx |
| rbp |
| return address of `main` | in `cg_invoke`
|--------------------------|
| frame of `main` |
| ... |
this->stack store the memory from b to a, inclusive.