btrace: change branch trace data structure

The branch trace is represented as 3 vectors:
  - a block vector
  - a instruction vector
  - a function vector

Each vector (except for the first) is computed from the one above.

Change this into a graph where a node represents a sequence of instructions
belonging to the same function and where we have three types of edges to connect
the function segments:
  - control flow
  - same function (instance)
  - call stack

This allows us to navigate in the branch trace.  We will need this for "record
goto" and reverse execution.

This patch introduces the data structure and computes the control flow edges.
It also introduces iterator structs to simplify iterating over the branch trace
in control-flow order.

It also fixes PR gdb/15240 since now recursive calls are handled correctly.
Fix the test that got the number of expected fib instances and also the
function numbers wrong.

The current instruction had been part of the branch trace.  This will look odd
once we start support for reverse execution.  Remove it.  We still keep it in
the trace itself to allow extending the branch trace more easily in the future.

2014-01-16  Markus Metzger  <markus.t.metzger@intel.com>

	* btrace.h (struct btrace_func_link): New.
	(enum btrace_function_flag): New.
	(struct btrace_inst): Rename to ...
	(struct btrace_insn): ...this. Update all users.
	(struct btrace_func) <ibegin, iend>: Remove.
	(struct btrace_func_link): New.
	(struct btrace_func): Rename to ...
	(struct btrace_function): ...this. Update all users.
	(struct btrace_function) <segment, flow, up, insn, insn_offset)
	(number, level, flags>: New.
	(struct btrace_insn_iterator): Rename to ...
	(struct btrace_insn_history): ...this.
	Update all users.
	(struct btrace_insn_iterator, btrace_call_iterator): New.
	(struct btrace_target_info) <btrace, itrace, ftrace>: Remove.
	(struct btrace_target_info) <begin, end, level>
	<insn_history, call_history>: New.
	(btrace_insn_get, btrace_insn_number, btrace_insn_begin)
	(btrace_insn_end, btrace_insn_prev, btrace_insn_next)
	(btrace_insn_cmp, btrace_find_insn_by_number, btrace_call_get)
	(btrace_call_number, btrace_call_begin, btrace_call_end)
	(btrace_call_prev, btrace_call_next, btrace_call_cmp)
	(btrace_find_function_by_number, btrace_set_insn_history)
	(btrace_set_call_history): New.
	* btrace.c (btrace_init_insn_iterator)
	(btrace_init_func_iterator, compute_itrace): Remove.
	(ftrace_print_function_name, ftrace_print_filename)
	(ftrace_skip_file): Change
	parameter to const.
	(ftrace_init_func): Remove.
	(ftrace_debug): Use new btrace_function fields.
	(ftrace_function_switched): Also consider gaining and
	losing symbol information).
	(ftrace_print_insn_addr, ftrace_new_call, ftrace_new_return)
	(ftrace_new_switch, ftrace_find_caller, ftrace_new_function)
	(ftrace_update_caller, ftrace_fixup_caller, ftrace_new_tailcall):
	New.
	(ftrace_new_function): Move. Remove debug print.
	(ftrace_update_lines, ftrace_update_insns): New.
	(ftrace_update_function): Check for call, ret, and jump.
	(compute_ftrace): Renamed to ...
	(btrace_compute_ftrace): ...this. Rewritten to compute call
	stack.
	(btrace_fetch, btrace_clear): Updated.
	(btrace_insn_get, btrace_insn_number, btrace_insn_begin)
	(btrace_insn_end, btrace_insn_prev, btrace_insn_next)
	(btrace_insn_cmp, btrace_find_insn_by_number, btrace_call_get)
	(btrace_call_number, btrace_call_begin, btrace_call_end)
	(btrace_call_prev, btrace_call_next, btrace_call_cmp)
	(btrace_find_function_by_number, btrace_set_insn_history)
	(btrace_set_call_history): New.
	* record-btrace.c (require_btrace): Use new btrace thread
	info fields.
	(record_btrace_info, btrace_insn_history)
	(record_btrace_insn_history, record_btrace_insn_history_range):
	Use new btrace thread info fields and new iterator.
	(btrace_func_history_src_line): Rename to ...
	(btrace_call_history_src_line): ...this. Use new btrace
	thread info fields.
	(btrace_func_history): Rename to ...
	(btrace_call_history): ...this. Use new btrace thread info
	fields and new iterator.
	(record_btrace_call_history, record_btrace_call_history_range):
	Use new btrace thread info fields and new iterator.

testsuite/
	* gdb.btrace/function_call_history.exp: Fix expected function
	trace.
	* gdb.btrace/instruction_history.exp: Initialize traced.
	Remove traced_functions.

1 files changed, 203 insertions, 34 deletions

diff --git a/gdb/btrace.h b/gdb/btrace.h
index 9bd7176..d219f69 100644
--- a/gdb/btrace.h
+++ b/gdb/btrace.h
@@ -29,63 +29,128 @@
 #include "btrace-common.h"
 
 struct thread_info;
+struct btrace_function;
 
 /* A branch trace instruction.
 
    This represents a single instruction in a branch trace.  */
-struct btrace_inst
+struct btrace_insn
 {
   /* The address of this instruction.  */
   CORE_ADDR pc;
 };
 
-/* A branch trace function.
+/* A vector of branch trace instructions.  */
+typedef struct btrace_insn btrace_insn_s;
+DEF_VEC_O (btrace_insn_s);
+
+/* A doubly-linked list of branch trace function segments.  */
+struct btrace_func_link
+{
+  struct btrace_function *prev;
+  struct btrace_function *next;
+};
+
+/* Flags for btrace function segments.  */
+enum btrace_function_flag
+{
+  /* The 'up' link interpretation.
+     If set, it points to the function segment we returned to.
+     If clear, it points to the function segment we called from.  */
+  BFUN_UP_LINKS_TO_RET = (1 << 0),
+
+  /* The 'up' link points to a tail call.  This obviously only makes sense
+     if bfun_up_links_to_ret is clear.  */
+  BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
+};
+
+/* A branch trace function segment.
 
    This represents a function segment in a branch trace, i.e. a consecutive
-   number of instructions belonging to the same function.  */
-struct btrace_func
+   number of instructions belonging to the same function.
+
+   We do not allow function segments without any instructions.  */
+struct btrace_function
 {
-  /* The full and minimal symbol for the function.  One of them may be NULL.  */
+  /* The full and minimal symbol for the function.  Both may be NULL.  */
   struct minimal_symbol *msym;
   struct symbol *sym;
 
+  /* The previous and next segment belonging to the same function.
+     If a function calls another function, the former will have at least
+     two segments: one before the call and another after the return.  */
+  struct btrace_func_link segment;
+
+  /* The previous and next function in control flow order.  */
+  struct btrace_func_link flow;
+
+  /* The directly preceding function segment in a (fake) call stack.  */
+  struct btrace_function *up;
+
+  /* The instructions in this function segment.
+     The instruction vector will never be empty.  */
+  VEC (btrace_insn_s) *insn;
+
+  /* The instruction number offset for the first instruction in this
+     function segment.  */
+  unsigned int insn_offset;
+
+  /* The function number in control-flow order.  */
+  unsigned int number;
+
+  /* The function level in a back trace across the entire branch trace.
+     A caller's level is one lower than the level of its callee.
+
+     Levels can be negative if we see returns for which we have not seen
+     the corresponding calls.  The branch trace thread information provides
+     a fixup to normalize function levels so the smallest level is zero.  */
+  int level;
+
   /* The source line range of this function segment (both inclusive).  */
   int lbegin, lend;
 
-  /* The instruction number range in the instruction trace corresponding
-     to this function segment (both inclusive).  */
-  unsigned int ibegin, iend;
+  /* A bit-vector of btrace_function_flag.  */
+  enum btrace_function_flag flags;
 };
 
-/* Branch trace may also be represented as a vector of:
+/* A branch trace instruction iterator.  */
+struct btrace_insn_iterator
+{
+  /* The branch trace function segment containing the instruction.
+     Will never be NULL.  */
+  const struct btrace_function *function;
 
-   - branch trace instructions starting with the oldest instruction.
-   - branch trace functions starting with the oldest function.  */
-typedef struct btrace_inst btrace_inst_s;
-typedef struct btrace_func btrace_func_s;
+  /* The index into the function segment's instruction vector.  */
+  unsigned int index;
+};
 
-/* Define functions operating on branch trace vectors.  */
-DEF_VEC_O (btrace_inst_s);
-DEF_VEC_O (btrace_func_s);
+/* A branch trace function call iterator.  */
+struct btrace_call_iterator
+{
+  /* The branch trace information for this thread.  Will never be NULL.  */
+  const struct btrace_thread_info *btinfo;
+
+  /* The branch trace function segment.
+     This will be NULL for the iterator pointing to the end of the trace.  */
+  const struct btrace_function *function;
+};
 
 /* Branch trace iteration state for "record instruction-history".  */
-struct btrace_insn_iterator
+struct btrace_insn_history
 {
-  /* The instruction index range from begin (inclusive) to end (exclusive)
-     that has been covered last time.
-     If end < begin, the branch trace has just been updated.  */
-  unsigned int begin;
-  unsigned int end;
+  /* The branch trace instruction range from BEGIN (inclusive) to
+     END (exclusive) that has been covered last time.  */
+  struct btrace_insn_iterator begin;
+  struct btrace_insn_iterator end;
 };
 
 /* Branch trace iteration state for "record function-call-history".  */
-struct btrace_func_iterator
+struct btrace_call_history
 {
-  /* The function index range from begin (inclusive) to end (exclusive)
-     that has been covered last time.
-     If end < begin, the branch trace has just been updated.  */
-  unsigned int begin;
-  unsigned int end;
+  /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
+     that has been covered last time.  */
+  struct btrace_call_iterator begin;
+  struct btrace_call_iterator end;
 };
 
 /* Branch trace information per thread.
@@ -103,16 +168,25 @@ struct btrace_thread_info
      the underlying architecture.  */
   struct btrace_target_info *target;
 
-  /* The current branch trace for this thread.  */
-  VEC (btrace_block_s) *btrace;
-  VEC (btrace_inst_s) *itrace;
-  VEC (btrace_func_s) *ftrace;
+  /* The current branch trace for this thread (both inclusive).
+
+     The last instruction of END is the current instruction, which is not
+     part of the execution history.
+     Both will be NULL if there is no branch trace available.  If there is
+     branch trace available, both will be non-NULL.  */
+  struct btrace_function *begin;
+  struct btrace_function *end;
+
+  /* The function level offset.  When added to each function's LEVEL,
+     this normalizes the function levels such that the smallest level
+     becomes zero.  */
+  int level;
 
   /* The instruction history iterator.  */
-  struct btrace_insn_iterator insn_iterator;
+  struct btrace_insn_history *insn_history;
 
   /* The function call history iterator.  */
-  struct btrace_func_iterator func_iterator;
+  struct btrace_call_history *call_history;
 };
 
 /* Enable branch tracing for a thread.  */
@@ -139,4 +213,99 @@ extern void btrace_free_objfile (struct objfile *);
 /* Parse a branch trace xml document into a block vector.  */
 extern VEC (btrace_block_s) *parse_xml_btrace (const char*);
 
+/* Dereference a branch trace instruction iterator.  Return a pointer to the
+   instruction the iterator points to.  */
+extern const struct btrace_insn *
+  btrace_insn_get (const struct btrace_insn_iterator *);
+
+/* Return the instruction number for a branch trace iterator.
+   Returns one past the maximum instruction number for the end iterator.
+   Returns zero if the iterator does not point to a valid instruction.  */
+extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
+
+/* Initialize a branch trace instruction iterator to point to the begin/end of
+   the branch trace.  Throws an error if there is no branch trace.  */
+extern void btrace_insn_begin (struct btrace_insn_iterator *,
+			       const struct btrace_thread_info *);
+extern void btrace_insn_end (struct btrace_insn_iterator *,
+			     const struct btrace_thread_info *);
+
+/* Increment/decrement a branch trace instruction iterator by at most STRIDE
+   instructions.  Return the number of instructions by which the instruction
+   iterator has been advanced.
+   Returns zero, if the operation failed or STRIDE had been zero.  */
+extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
+				      unsigned int stride);
+extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
+				      unsigned int stride);
+
+/* Compare two branch trace instruction iterators.
+   Return a negative number if LHS < RHS.
+   Return zero if LHS == RHS.
+   Return a positive number if LHS > RHS.  */
+extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
+			    const struct btrace_insn_iterator *rhs);
+
+/* Find an instruction in the function branch trace by its number.
+   If the instruction is found, initialize the branch trace instruction
+   iterator to point to this instruction and return non-zero.
+   Return zero otherwise.  */
+extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
+				       const struct btrace_thread_info *,
+				       unsigned int number);
+
+/* Dereference a branch trace call iterator.  Return a pointer to the
+   function the iterator points to or NULL if the interator points past
+   the end of the branch trace.  */
+extern const struct btrace_function *
+  btrace_call_get (const struct btrace_call_iterator *);
+
+/* Return the function number for a branch trace call iterator.
+   Returns one past the maximum function number for the end iterator.
+   Returns zero if the iterator does not point to a valid function.  */
+extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
+
+/* Initialize a branch trace call iterator to point to the begin/end of
+   the branch trace.  Throws an error if there is no branch trace.  */
+extern void btrace_call_begin (struct btrace_call_iterator *,
+			       const struct btrace_thread_info *);
+extern void btrace_call_end (struct btrace_call_iterator *,
+			     const struct btrace_thread_info *);
+
+/* Increment/decrement a branch trace call iterator by at most STRIDE function
+   segments.  Return the number of function segments by which the call
+   iterator has been advanced.
+   Returns zero, if the operation failed or STRIDE had been zero.  */
+extern unsigned int btrace_call_next (struct btrace_call_iterator *,
+				      unsigned int stride);
+extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
+				      unsigned int stride);
+
+/* Compare two branch trace call iterators.
+   Return a negative number if LHS < RHS.
+   Return zero if LHS == RHS.
+   Return a positive number if LHS > RHS.  */
+extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
+			    const struct btrace_call_iterator *rhs);
+
+/* Find a function in the function branch trace by its NUMBER.
+   If the function is found, initialize the branch trace call
+   iterator to point to this function and return non-zero.
+   Return zero otherwise.  */
+extern int btrace_find_call_by_number (struct btrace_call_iterator *,
+				       const struct btrace_thread_info *,
+				       unsigned int number);
+
+/* Set the branch trace instruction history from BEGIN (inclusive) to
+   END (exclusive).  */
+extern void btrace_set_insn_history (struct btrace_thread_info *,
+				     const struct btrace_insn_iterator *begin,
+				     const struct btrace_insn_iterator *end);
+
+/* Set the branch trace function call history from BEGIN (inclusive) to
+   END (exclusive).  */
+extern void btrace_set_call_history (struct btrace_thread_info *,
+				     const struct btrace_call_iterator *begin,
+				     const struct btrace_call_iterator *end);
+
 #endif /* BTRACE_H */