perf annotate-arm64: Support load instruction tracking

Extend update_insn_state_arm64() to handle load instructions, tracking
register state changes when data is loaded from memory to registers.

Two main categories are considered: standard load (e.g, ldr variants)
and load pair (ldp), for example:

  ldr dst, [src, #imm]
  ldp dst1, dst2, [src, #imm]

For data type propagation, a load pair can be treated as two standard
loads combined, first loading dst1 and then dst2. The difference is
that when loading dst2, an additional memory spacing 'mem_spacing' after
the first load must be added. This mem_spacing can be derived from the
instruction mnemonic and the size of the dst register. Each load operation
is handled by introducing propagate_load_reg_state().

When processing a load pair, the case where dst and src registers are
the same (e.g., ldp x0, x1, [x0]) also needs to be considered. Therefore,
before propagating data types, a snapshot of the src register's state
must be saved and then passed to propagate_load_reg_state().

Finally, handle the side effects of pre-index and post-index addressing
via adjust_reg_index_state().

A real-world example is shown below:

  ffff80008011f5b0 <pick_task_stop>:
  ffff80008011f5b8:  ldr  x0, [x0, #2712] // x0: struct rq* -> task_struct*
* ffff80008011f5c0:  ldr  w1, [x0, #104]

Before this commit, the type of x0 was incorrectly inferred as 'struct rq':

  find data type for 0x68(reg0) at pick_task_stop+0x10
  var [8] reg0 offset 0 type='struct rq*'
  chk [10] reg0 offset=0x68 ok=1 kind=1 (struct rq*) : Good!
  final result:  type='struct rq'

After this commit, the type of x0 is correctly inferred as 'struct task_struct':

  find data type for 0x68(reg0) at pick_task_stop+0x10
  var [8] reg0 offset 0 type='struct rq*'
  ldr [8] 0xa98(reg0) -> reg0 type='struct task_struct*'
  chk [10] reg0 offset=0x68 ok=1 kind=1 (struct task_struct*) : Good!
  final result: type='struct task_struct'

Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions