* loop-iv.c: New file.

	* Makefile.in (loop-iv.o): New.
	* basic_block.h (FOR_BB_INSNS, FOR_BB_INSNS_REVERSE): New macros.
	* cfgloop.c (fill_sons_in_loop, get_loop_body_in_dom_order,
	num_loop_branches): New functions.
	* cfgloop.h (get_loop_body_in_dom_order, num_loop_branches,
	iv_analysis_loop_init, iv_get_reaching_def, iv_analyse, get_iv_value,
	find_simple_exit, iv_number_of_iterations, iv_analysis_done,
	get_simple_loop_desc, free_simple_loop_desc): Declare.
	(simple_loop_desc): New inline function.
	(struct rtx_iv, struct niter_desc): New.
	* cfgloopmanip.c (loopify): Specify semantics more precisely.
	* expr.c (force_operand): Handle subregs of expressions created by
	loop unroller.
	* loop-init.c (loop_optimizer_init, loop_optimizer_finalize): Move
	parts of the initialization to toplev.c
	* loop-unroll.c (loop_exit_at_end_p): New.
	(unroll_and_peel_loops): Call iv_analysis_done.
	(decide_peel_once_rolling, decide_peel_completely,
	decide_unroll_stupid, decide_unroll_constant_iterations,
	decide_unroll_runtime_iterations, decide_peel_simple,
	peel_loop_simple, unroll_loop_stupid, unroll_loop_constant_iterations,
	unroll_loop_runtime_iterations): Use new simple loop analysis.
	* loop-unswitch.c (compare_and_jump_seq): New.
	(may_unswitch_on_p): Renamed to ...
	(may_unswitch_on): Use new iv analysis.
	(reversed_condition): Export.
	(unswitch_single_loop, unswitch_loop): Use new iv analysis.
	* predict.c (estimate_probability): Use new simple loop analysis.
	* rtl.h (get_mode_bounds, reversed_condition,compare_and_jump_seq,
	canon_condition, simplify_using_condition): Declare.
	* stor-layout.c (get_mode_bounds): New.
	* toplev.c (rest_of_handle_loop2): Some parts of
	initialization/finalization moved here from loop-init.c.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@77951 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 110 insertions, 0 deletions

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index 4d8c67dd35d..58184b5e29b 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -278,7 +278,9 @@ extern int average_num_loop_insns (struct loop *);
 
 /* Loops & cfg manipulation.  */
 extern basic_block *get_loop_body (const struct loop *);
+extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 extern edge *get_loop_exit_edges (const struct loop *, unsigned *);
+extern unsigned num_loop_branches (const struct loop *);
 
 extern edge loop_preheader_edge (const struct loop *);
 extern edge loop_latch_edge (const struct loop *);
@@ -322,6 +324,114 @@ extern void unloop (struct loops *, struct loop *);
 extern bool remove_path (struct loops *, edge);
 extern edge split_loop_bb (basic_block, rtx);
 
+/* Induction variable analysis.  */
+
+/* The description of induction variable.  The things are a bit complicated
+   due to need to handle subregs and extends.  The value of the object described
+   by it can be obtained as follows (all computations are done in extend_mode):
+
+   Value in i-th iteration is
+     delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
+
+   If first_special is true, the value in the first iteration is
+     delta + mult * base
+     
+   If extend = NIL, first_special must be false, delta 0, mult 1 and value is
+     subreg_{mode} (base + i * step)
+
+   The get_iv_value function can be used to obtain these expressions.
+
+   ??? Add a third mode field that would specify the mode in that inner
+   computation is done, which would enable it to be different from the
+   outer one?  */
+
+struct rtx_iv
+{
+  /* Its base and step (mode of base and step is supposed to be extend_mode,
+     see the description above).  */
+  rtx base, step;
+
+  /* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or NIL).  */
+  enum rtx_code extend;
+
+  /* Operations applied in the extended mode.  */
+  rtx delta, mult;
+
+  /* The mode it is extended to.  */
+  enum machine_mode extend_mode;
+
+  /* The mode the variable iterates in.  */
+  enum machine_mode mode;
+
+  /* Whether we have already filled the remaining fields.  */
+  unsigned analysed : 1;
+
+  /* Whether the first iteration needs to be handled specially.  */
+  unsigned first_special : 1;
+};
+
+/* This should replace struct loop_desc.  We keep this just so that we are
+   able to compare the results.  */
+
+struct niter_desc
+{
+  /* The edge out of the loop.  */
+  edge out_edge;
+
+  /* The other edge leading from the condition.  */
+  edge in_edge;
+
+  /* True if we are able to say anything about number of iterations of the
+     loop.  */
+  bool simple_p;
+
+  /* True if the loop iterates the constant number of times.  */
+  bool const_iter;
+
+  /* Number of iterations if constant.  */
+  unsigned HOST_WIDEST_INT niter;
+
+  /* Upper bound on the number of iterations.  */
+  unsigned HOST_WIDEST_INT niter_max;
+
+  /* Assumptions under that the rest of the information is valid.  */
+  rtx assumptions;
+
+  /* Assumptions under that the loop ends before reaching the latch,
+     even if value of niter_expr says otherwise.  */
+  rtx noloop_assumptions;
+
+  /* Condition under that the loop is infinite.  */
+  rtx infinite;
+
+  /* Whether the comparison is signed.  */
+  bool signed_p;
+
+  /* The mode in that niter_expr should be computed.  */
+  enum machine_mode mode;
+
+  /* The number of iterations of the loop.  */
+  rtx niter_expr;
+};
+
+extern void iv_analysis_loop_init (struct loop *);
+extern rtx iv_get_reaching_def (rtx, rtx);
+extern bool iv_analyse (rtx, rtx, struct rtx_iv *);
+extern rtx get_iv_value (struct rtx_iv *, rtx);
+extern void find_simple_exit (struct loop *, struct niter_desc *);
+extern void iv_number_of_iterations (struct loop *, rtx, rtx,
+				     struct niter_desc *);
+extern void iv_analysis_done (void);
+
+extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
+extern void free_simple_loop_desc (struct loop *loop);
+
+static inline struct niter_desc *
+simple_loop_desc (struct loop *loop)
+{
+  return loop->aux;
+}
+
 /* Loop optimizer initialization.  */
 extern struct loops *loop_optimizer_init (FILE *);
 extern void loop_optimizer_finalize (struct loops *, FILE *);