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Re: [PATCH] Use an std::vector for inline_states
On 2018-04-07 03:28 PM, Pedro Alves wrote:
> On 04/07/2018 03:42 PM, Simon Marchi wrote:
>
>> /* Locate saved inlined frame state for PTID, if it exists
>> and is valid. */
>> @@ -66,43 +70,29 @@ static VEC(inline_state_s) *inline_states;
>> static struct inline_state *
>> find_inline_frame_state (ptid_t ptid)
>> {
>
>> - if (current_pc != state->saved_pc)
>> - {
>> - /* PC has changed - this context is invalid. Use the
>> - default behavior. */
>> - VEC_unordered_remove (inline_state_s, inline_states, ix);
>> - return NULL;
>
> ...
>
>> - state = VEC_safe_push (inline_state_s, inline_states, NULL);
>> - memset (state, 0, sizeof (*state));
>> - state->ptid = ptid;
>> + inline_states.erase (state_it);
>
> The patch looks good, though it made me realize that when we're
> replacing VEC_unordered_remove with std::vector::erase, we're introducing
> a pessimization, which makes me ponder about having an utility/replacement
> for VEC_unordered_remove that works with std::vector and alikes.
> I.e., a function that removes an element from a vector simply by moving
> the last element to the now-vacant position. That's more efficient
> than erase, because it avoids having to copy/move the remaining
> elements, making it O(1).
>
> Something like:
>
> template<typename Vector>
> void
> unordered_erase (Vector &v, typename Vector::const_iterator pos)
> {
> *pos = std::move (v.back ());
> v.pop_back ();
> }
>
> Thanks,
> Pedro Alves
>
How about this (modulo the fact that unordered_remove should be renamed to
unordered_erase to align with the STL)?
>From a7c9bbe86dd2e75c826e0ac0d10db97de7b802d0 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Sat, 7 Apr 2018 10:42:05 -0400
Subject: [PATCH] Use an std::vector for inline_states
This patch replaces VEC(inline_state) with std::vector<inline_state> and
adjusts the code that uses it.
gdb/ChangeLog:
* common/gdb_vecs.h (unordered_remove): Add overload that takes
an iterator.
* inline-frame.c: Include <algorithm>.
(struct inline_state): Add constructor.
(inline_state_s): Remove.
(DEF_VEC_O(inline_state_s)): Remove.
(inline_states): Change type to std::vector.
(find_inline_frame_state): Adjust to std::vector.
(allocate_inline_frame_state): Remove.
(clear_inline_frame_state): Adjust to std::vector.
(skip_inline_frames): Adjust to std::vector.
---
gdb/common/gdb_vecs.h | 22 +++++++---
gdb/inline-frame.c | 113 +++++++++++++++++++++-----------------------------
2 files changed, 65 insertions(+), 70 deletions(-)
diff --git a/gdb/common/gdb_vecs.h b/gdb/common/gdb_vecs.h
index 141d05e0189a..3e461dca4838 100644
--- a/gdb/common/gdb_vecs.h
+++ b/gdb/common/gdb_vecs.h
@@ -47,6 +47,22 @@ extern void dirnames_to_char_ptr_vec_append
extern std::vector<gdb::unique_xmalloc_ptr<char>>
dirnames_to_char_ptr_vec (const char *dirnames);
+/* Remove the element pointed by iterator IT from VEC, not preserving the order
+ of the remaining elements. Return the removed element. */
+
+template <typename T>
+T
+unordered_remove (std::vector<T> &vec, typename std::vector<T>::iterator it)
+{
+ gdb_assert (it >= vec.begin () && it < vec.end ());
+
+ T removed = std::move (*it);
+ *it = std::move (vec.back ());
+ vec.pop_back ();
+
+ return removed;
+}
+
/* Remove the element at position IX from VEC, not preserving the order of the
remaining elements. Return the removed element. */
@@ -56,11 +72,7 @@ unordered_remove (std::vector<T> &vec, typename std::vector<T>::size_type ix)
{
gdb_assert (ix < vec.size ());
- T removed = std::move (vec[ix]);
- vec[ix] = std::move (vec.back ());
- vec.pop_back ();
-
- return removed;
+ return unordered_remove (vec, vec.begin () + ix);
}
/* Remove the element at position IX from VEC, preserving the order the
diff --git a/gdb/inline-frame.c b/gdb/inline-frame.c
index a01961955949..4333a3d82b05 100644
--- a/gdb/inline-frame.c
+++ b/gdb/inline-frame.c
@@ -27,6 +27,7 @@
#include "symtab.h"
#include "vec.h"
#include "frame.h"
+#include <algorithm>
/* We need to save a few variables for every thread stopped at the
virtual call site of an inlined function. If there was always a
@@ -34,6 +35,12 @@
keep our own list. */
struct inline_state
{
+ inline_state (ptid_t ptid_, int skipped_frames_, CORE_ADDR saved_pc_,
+ symbol *skipped_symbol_)
+ : ptid (ptid_), skipped_frames (skipped_frames_), saved_pc (saved_pc_),
+ skipped_symbol (skipped_symbol_)
+ {}
+
/* The thread this data relates to. It should be a currently
stopped thread; we assume thread IDs never change while the
thread is stopped. */
@@ -55,10 +62,7 @@ struct inline_state
struct symbol *skipped_symbol;
};
-typedef struct inline_state inline_state_s;
-DEF_VEC_O(inline_state_s);
-
-static VEC(inline_state_s) *inline_states;
+static std::vector<inline_state> inline_states;
/* Locate saved inlined frame state for PTID, if it exists
and is valid. */
@@ -66,43 +70,29 @@ static VEC(inline_state_s) *inline_states;
static struct inline_state *
find_inline_frame_state (ptid_t ptid)
{
- struct inline_state *state;
- int ix;
-
- for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++)
- {
- if (ptid_equal (state->ptid, ptid))
- {
- struct regcache *regcache = get_thread_regcache (ptid);
- CORE_ADDR current_pc = regcache_read_pc (regcache);
-
- if (current_pc != state->saved_pc)
- {
- /* PC has changed - this context is invalid. Use the
- default behavior. */
- VEC_unordered_remove (inline_state_s, inline_states, ix);
- return NULL;
- }
- else
- return state;
- }
- }
+ auto state_it = std::find_if (inline_states.begin (), inline_states.end (),
+ [&ptid] (const inline_state &state)
+ {
+ return ptid == state.ptid;
+ });
- return NULL;
-}
+ if (state_it == inline_states.end ())
+ return nullptr;
-/* Allocate saved inlined frame state for PTID. */
+ inline_state &state = *state_it;
+ struct regcache *regcache = get_thread_regcache (ptid);
+ CORE_ADDR current_pc = regcache_read_pc (regcache);
-static struct inline_state *
-allocate_inline_frame_state (ptid_t ptid)
-{
- struct inline_state *state;
+ if (current_pc != state.saved_pc)
+ {
+ /* PC has changed - this context is invalid. Use the
+ default behavior. */
- state = VEC_safe_push (inline_state_s, inline_states, NULL);
- memset (state, 0, sizeof (*state));
- state->ptid = ptid;
+ unordered_remove (inline_states, state_it);
+ return nullptr;
+ }
- return state;
+ return &state;
}
/* Forget about any hidden inlined functions in PTID, which is new or
@@ -112,36 +102,34 @@ allocate_inline_frame_state (ptid_t ptid)
void
clear_inline_frame_state (ptid_t ptid)
{
- struct inline_state *state;
- int ix;
-
- if (ptid_equal (ptid, minus_one_ptid))
+ if (ptid == minus_one_ptid)
{
- VEC_free (inline_state_s, inline_states);
+ inline_states.clear ();
return;
}
- if (ptid_is_pid (ptid))
+ if (ptid.is_pid ())
{
- VEC (inline_state_s) *new_states = NULL;
- int pid = ptid_get_pid (ptid);
-
- for (ix = 0;
- VEC_iterate (inline_state_s, inline_states, ix, state);
- ix++)
- if (pid != ptid_get_pid (state->ptid))
- VEC_safe_push (inline_state_s, new_states, state);
- VEC_free (inline_state_s, inline_states);
- inline_states = new_states;
+ int pid = ptid.pid ();
+ auto it = std::remove_if (inline_states.begin (), inline_states.end (),
+ [pid] (const inline_state &state)
+ {
+ return pid == state.ptid.pid ();
+ });
+
+ inline_states.erase (it, inline_states.end ());
+
return;
}
- for (ix = 0; VEC_iterate (inline_state_s, inline_states, ix, state); ix++)
- if (ptid_equal (state->ptid, ptid))
- {
- VEC_unordered_remove (inline_state_s, inline_states, ix);
- return;
- }
+ auto it = std::find_if (inline_states.begin (), inline_states.end (),
+ [&ptid] (const inline_state &state)
+ {
+ return ptid == state.ptid;
+ });
+
+ if (it != inline_states.end ())
+ inline_states.erase (it);
}
static void
@@ -303,16 +291,14 @@ block_starting_point_at (CORE_ADDR pc, const struct block *block)
void
skip_inline_frames (ptid_t ptid)
{
- CORE_ADDR this_pc;
const struct block *frame_block, *cur_block;
struct symbol *last_sym = NULL;
int skip_count = 0;
- struct inline_state *state;
/* This function is called right after reinitializing the frame
cache. We try not to do more unwinding than absolutely
necessary, for performance. */
- this_pc = get_frame_pc (get_current_frame ());
+ CORE_ADDR this_pc = get_frame_pc (get_current_frame ());
frame_block = block_for_pc (this_pc);
if (frame_block != NULL)
@@ -341,10 +327,7 @@ skip_inline_frames (ptid_t ptid)
}
gdb_assert (find_inline_frame_state (ptid) == NULL);
- state = allocate_inline_frame_state (ptid);
- state->skipped_frames = skip_count;
- state->saved_pc = this_pc;
- state->skipped_symbol = last_sym;
+ inline_states.emplace_back (ptid, skip_count, this_pc, last_sym);
if (skip_count != 0)
reinit_frame_cache ();
--
2.16.3