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authorSimon Marchi <simon.marchi@efficios.com>2024-02-19 13:07:47 -0500
committerSimon Marchi <simon.marchi@efficios.com>2024-02-20 10:42:25 -0500
commit8480a37e146c40e82a93c0ecf6144571516c95c5 (patch)
treebfa5d1e14e5212821ee29ae5099be72399137036 /gdb/dummy-frame.c
parent1b2c120daf9e2d935453f9051bbeafbac7f9f14d (diff)
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gdb: pass frames as `const frame_info_ptr &`
We currently pass frames to function by value, as `frame_info_ptr`. This is somewhat expensive: - the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass by value - the constructors and destructor link/unlink the object in the global `frame_info_ptr::frame_list` list. This is an `intrusive_list`, so it's not so bad: it's just assigning a few points, there's no memory allocation as if it was `std::list`, but still it's useless to do that over and over. As suggested by Tom Tromey, change many function signatures to accept `const frame_info_ptr &` instead of `frame_info_ptr`. Some functions reassign their `frame_info_ptr` parameter, like: void the_func (frame_info_ptr frame) { for (; frame != nullptr; frame = get_prev_frame (frame)) { ... } } I wondered what to do about them, do I leave them as-is or change them (and need to introduce a separate local variable that can be re-assigned). I opted for the later for consistency. It might not be clear why some functions take `const frame_info_ptr &` while others take `frame_info_ptr`. Also, if a function took a `frame_info_ptr` because it did re-assign its parameter, I doubt that we would think to change it to `const frame_info_ptr &` should the implementation change such that it doesn't need to take `frame_info_ptr` anymore. It seems better to have a simple rule and apply it everywhere. Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0 Approved-By: Andrew Burgess <aburgess@redhat.com>
Diffstat (limited to 'gdb/dummy-frame.c')
-rw-r--r--gdb/dummy-frame.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/gdb/dummy-frame.c b/gdb/dummy-frame.c
index 309483d..5969ef2 100644
--- a/gdb/dummy-frame.c
+++ b/gdb/dummy-frame.c
@@ -288,7 +288,7 @@ struct dummy_frame_cache
static int
dummy_frame_sniffer (const struct frame_unwind *self,
- frame_info_ptr this_frame,
+ const frame_info_ptr &this_frame,
void **this_prologue_cache)
{
/* When unwinding a normal frame, the stack structure is determined
@@ -334,7 +334,7 @@ dummy_frame_sniffer (const struct frame_unwind *self,
register value is taken from the local copy of the register buffer. */
static struct value *
-dummy_frame_prev_register (frame_info_ptr this_frame,
+dummy_frame_prev_register (const frame_info_ptr &this_frame,
void **this_prologue_cache,
int regnum)
{
@@ -364,7 +364,7 @@ dummy_frame_prev_register (frame_info_ptr this_frame,
dummy cache is located and saved in THIS_PROLOGUE_CACHE. */
static void
-dummy_frame_this_id (frame_info_ptr this_frame,
+dummy_frame_this_id (const frame_info_ptr &this_frame,
void **this_prologue_cache,
struct frame_id *this_id)
{
@@ -390,7 +390,7 @@ const struct frame_unwind dummy_frame_unwind =
/* See dummy-frame.h. */
struct frame_id
-default_dummy_id (struct gdbarch *gdbarch, frame_info_ptr this_frame)
+default_dummy_id (struct gdbarch *gdbarch, const frame_info_ptr &this_frame)
{
CORE_ADDR sp, pc;