From fdd2bd920bd67e6a1e877baf52b9c138c00da13f Mon Sep 17 00:00:00 2001 From: Tim Wiederhake Date: Mon, 21 Nov 2016 16:39:57 +0100 Subject: [PATCH] btrace: Use binary search to find instruction. Currently, btrace_find_insn_by_number will iterate over all function call segments to find the one that contains the needed instruction. This linear search is too slow for the upcoming Python bindings that will use this function to access instructions. This patch introduces a vector in struct btrace_thread_info that holds pointers to all recorded function segments and allows to use binary search. The proper solution is to turn the underlying tree into a vector of objects and use indices for access. This requires more work. A patch set is currently being worked on and will be published later. Signed-off-by: Tim Wiederhake gdb/ChangeLog: * btrace.c (btrace_fetch): Copy function call segments pointer into a vector. (btrace_clear): Clear the vector. (btrace_find_insn_by_number): Use binary search to find the correct function call segment. * btrace.h (brace_fun_p): New typedef. (struct btrace_thread_info) : New field. Change-Id: I8a7f67e80bfe4ff62c4192f74a2153a70bf2a035 --- gdb/btrace.c | 45 +++++++++++++++++++++++++++++++++++++++------ gdb/btrace.h | 7 +++++++ 2 files changed, 46 insertions(+), 6 deletions(-) diff --git a/gdb/btrace.c b/gdb/btrace.c index 06122cdfbb..95dc7abb55 100644 --- a/gdb/btrace.c +++ b/gdb/btrace.c @@ -1839,13 +1839,19 @@ btrace_fetch (struct thread_info *tp) /* Compute the trace, provided we have any. */ if (!btrace_data_empty (&btrace)) { + struct btrace_function *bfun; + /* Store the raw trace data. The stored data will be cleared in btrace_clear, so we always append the new trace. */ btrace_data_append (&btinfo->data, &btrace); btrace_maint_clear (btinfo); + VEC_truncate (btrace_fun_p, btinfo->functions, 0); btrace_clear_history (btinfo); btrace_compute_ftrace (tp, &btrace); + + for (bfun = btinfo->begin; bfun != NULL; bfun = bfun->flow.next) + VEC_safe_push (btrace_fun_p, btinfo->functions, bfun); } do_cleanups (cleanup); @@ -1868,6 +1874,8 @@ btrace_clear (struct thread_info *tp) btinfo = &tp->btrace; + VEC_free (btrace_fun_p, btinfo->functions); + it = btinfo->begin; while (it != NULL) { @@ -2458,20 +2466,45 @@ btrace_find_insn_by_number (struct btrace_insn_iterator *it, unsigned int number) { const struct btrace_function *bfun; + unsigned int upper, lower; - for (bfun = btinfo->end; bfun != NULL; bfun = bfun->flow.prev) - if (bfun->insn_offset <= number) - break; + if (VEC_empty (btrace_fun_p, btinfo->functions)) + return 0; - if (bfun == NULL) + lower = 0; + bfun = VEC_index (btrace_fun_p, btinfo->functions, lower); + if (number < bfun->insn_offset) return 0; - if (bfun->insn_offset + ftrace_call_num_insn (bfun) <= number) + upper = VEC_length (btrace_fun_p, btinfo->functions) - 1; + bfun = VEC_index (btrace_fun_p, btinfo->functions, upper); + if (number >= bfun->insn_offset + ftrace_call_num_insn (bfun)) return 0; + /* We assume that there are no holes in the numbering. */ + for (;;) + { + const unsigned int average = lower + (upper - lower) / 2; + + bfun = VEC_index (btrace_fun_p, btinfo->functions, average); + + if (number < bfun->insn_offset) + { + upper = average - 1; + continue; + } + + if (number >= bfun->insn_offset + ftrace_call_num_insn (bfun)) + { + lower = average + 1; + continue; + } + + break; + } + it->function = bfun; it->index = number - bfun->insn_offset; - return 1; } diff --git a/gdb/btrace.h b/gdb/btrace.h index 1c0b6b3896..07ed10c6ad 100644 --- a/gdb/btrace.h +++ b/gdb/btrace.h @@ -187,6 +187,9 @@ struct btrace_function btrace_function_flags flags; }; +typedef struct btrace_function *btrace_fun_p; +DEF_VEC_P (btrace_fun_p); + /* A branch trace instruction iterator. */ struct btrace_insn_iterator { @@ -337,6 +340,10 @@ struct btrace_thread_info struct btrace_function *begin; struct btrace_function *end; + /* Vector of pointer to decoded function segments. These are in execution + order with the first element == BEGIN and the last element == END. */ + VEC (btrace_fun_p) *functions; + /* The function level offset. When added to each function's LEVEL, this normalizes the function levels such that the smallest level becomes zero. */ -- 2.34.1