[SFN] introduce statement frontier notes, still disabled

This patch completes the infrastructure for the introduction of
statement frontiers in C-family languages.

It brings in all the code remaining code needed to introduce and
transform begin stmt trees, gimple stmts, insns and notes, and
ultimately use them to generate the is_stmt column in DWARF2+ line
number tables/programs, however none of it is activated: the option
that would do so will be introduced in a subsequent patch.

This patch depends on an earlier patch with not-quite-boilerplate
changes towards SFN.

for  gcc/c-family/ChangeLog

	* c-semantics.c (pop_stmt_list): Move begin stmt marker into
	subsequent statement list.

for  gcc/c/ChangeLog

	* c-objc-common.h (LANG_HOOKS_EMITS_BEGIN_STMT): Redefine as true.
	* c-parser.c (add_debug_begin_stmt): New.
	(c_parser_declaration_or_fndef): Call it.
	(c_parser_compound_statement_nostart): Likewise.
	(c_parser_statement_after_labels): Likewise.
	* c-typeck (c_finish_stmt_expr): Skip begin stmts markers.

for  gcc/cp/ChangeLog

	* constexpr.c (check_constexpr_ctor_body_1): Skip begin stmt
	markers.
	(constexpr_fn_retval): Likewise.
	(potential_constant_expression_1): Likewise.
	(cxx_eval_statement_list): Check that a begin stmt marker is
	not used as the value of a statement list.
	(cxx_eval_constant_expression): Return begin stmt markers
	unchanged.
	* cp-array-notation.c (stmt_location): New.
	(cp_expand_cond_array_notations): Use it.
	* cp-objcp-common.h (LANG_HOOKS_EMITS_BEGIN_STMT): Redefine as true.
	* parser.c (add_debug_begin_stmt): New.
	(cp_parser_statement): Call it.
	* pt.c (tsubst_copy): Handle begin stmt markers.

for  gcc/ChangeLog

	* cfgexpand.c (expand_gimple_basic_block): Handle begin stmt
	markers.  Integrate source bind into debug stmt expand loop.
	(pass_expand::execute): Check debug marker limit.  Avoid deep
	TER and expand debug locations for debug bind insns only.
	* cse.c (insn_live_p): Keep nonbind markers and debug bindings
	followed by them.
	* df-scan.c (df_insn_delete): Accept out-of-block debug insn.
	* final.c (reemit_insn_block_notes): Take current block from
	nonbind markers.  Declare note where it's first set.
	(final_scan_insn): Handle begin stmt notes.  Emit is_stmt according to
	begin stmt markers if enabled.
	(notice_source_line): Handle nonbind markers.  Fail if their
	location is unknown or that of builtins.
	(rest_of_handle_final): Convert begin stmt markers to notes if
	var-tracking didn't run.
	(rest_of_clean_state): Skip begin stmt markers.
	* gimple-pretty-print.c (dump_gimple_debug): Handle begin stmt
	markers.
	* function.c (allocate_struct_function): Set begin_stmt_markers.
	* function.h (struct function): Add debug_marker_count counter
	and debug_nonbind_markers flag.
	* gimple-iterator.c (gsi_remove): Adjust debug_marker_count.
	* gimple-low.c (lower_function_body): Adjust
	debug_nonbind_markers.
	(lower_stmt): Drop or skip gimple debug stmts.
	(lower_try_catch): Skip debug stmts.
	* gimple.c (gimple_build_debug_begin_stmt): New.
	(gimple_copy): Increment debug_marker_count if copying one.
	* gimple.h (gimple_build_debug_begin_stmt): Declare.
	* gimplify.c (rexpr_location): New.
	(rexpr_has_location): New.
	(warn_switch_unreachable_r): Handle gimple debug stmts.
	(shortcut_cond_r): Call expr_location.
	(find_goto): New.
	(find_goto_label): New.
	(shortcut_cond_expr): Call expr_has_location, expr_location, and
	find_goto_label.
	(gimplify_cond_expr): Call find_goto_label, expr_has_location, and
	expr_location.
	(gimplify_expr): Handle begin stmt markers.  Reject debug expr decls.
	* langhooks-def.h (LANG_HOOKS_EMITS_BEGIN_STMT): New.  Add to...
	(LANG_HOOKS_INITIALIZER): ... this.
	* langhooks.h (struct lang_hooks): Add emits_begin_stmt.
	* lra-contraints.c (inherit_reload_reg): Tolerate between-blocks
	debug insns.
	(update_ebb_live_info): Skip debug insn markers.
	* lra.c (debug_insn_static_data): Rename to...
	(debug_bind_static_data): ... this.
	(debug_marker_static_data): New.
	(lra_set_insn_recog_data): Select one of the above depending
	on debug insn kind.
	(lra_update_isn_regno_info): Don't assume debug insns have
	freqs.
	(push_insns): Skip debug insns.
	* lto-streamer-in.c (input_function): Drop debug stmts
	depending on active options.  Adjust debug_nonbind_markers.
	* params.def (PARAM_MAX_DEBUG_MARKER_COUNT): New.
	* print-rtl.c (rtx_writer::print_rtx_operand_code_0): Handle
	begin stmt marker notes.
	(print_insn): Likewise.
	* recog.c (extract_insn): Recognize rtl for debug markers.
	* rtl.def (DEBUG_MARKER): New.
	* tree-inline.c: Include params.h.
	(remap_gimple_stmt): Handle nonbind markers.
	(maybe_move_debug_stmts_to_successors): Likewise.
	(copy_debug_stmt): Likewise.
	* tree-iterator.c (append_to_statement_list_1): Append begin stmt
	markers regardless of no side effects.
	(tsi_link_before): Don't update container's side effects when adding
	a begin stmt marker.
	(tsi_link_after): Likewise.
	(expr_first): Skip begin stmt markers.
	(expr_last): Likewise.
	* tree-pretty-print (dump_generic_node): Handle begin stmt markers.
	* tree-ssa-threadedge.c (propagate_threaded_block_debug_info):
	Disregard nonbind markers.
	* tree.c (make_node_stat): Don't set side effects for begin stmt
	markers.
	(build1_stat): Likewise.
	* tree.def (DEBUG_BEGIN_STMT): New.
	* tree.h (GOTO_DESTINATION): Require a GOTO_EXPR.
	* var-tracking.c (delete_debug_insns): Renamed to...
	(delete_vta_debug_insns): ... this.
	(reemit_marker_as_note): New.
	(vt_initialize): Reemit markers.
	(delete_vta_debug_insns): Likewise.
	(vt_debug_insns_local): Reemit or delete markers.
	(variable_tracking_main_1): Likewise.
	* doc/generic.texi (DEBUG_BEGIN_STMT): Document.
	* doc/gimple.texi (gimple_debug_begin_stmt_p): New.
	(gimple_debug_nonbind_marker_p): New.
	(gimple_build_debug_bind): Adjust.
	(gimple_build_debug_begin_stmt): New.
	* doc/invoke.texi (max-debug-marker-count): New param.
	* doc/rtl.texi (debug_implicit_ptr, entry_value): New.
	(debug_parameter_ref, debug_marker): New.
	(NOTE_INSN_BEGIN_STMT): New.
	(DEBUG_INSN): Describe begin stmt markers.

From-SVN: r255568

1 files changed, 29 insertions, 0 deletions

diff --git a/gcc/gimple-low.c b/gcc/gimple-low.c
index 22db61b..95f3f45 100644
--- a/gcc/gimple-low.c
+++ b/gcc/gimple-low.c
@@ -110,6 +110,17 @@ lower_function_body (void)
 
   i = gsi_last (lowered_body);
 
+  /* If we had begin stmt markers from e.g. PCH, but this compilation
+     doesn't want them, lower_stmt will have cleaned them up; we can
+     now clear the flag that indicates we had them.  */
+  if (!MAY_HAVE_DEBUG_MARKER_STMTS && cfun->debug_nonbind_markers)
+    {
+      /* This counter needs not be exact, but before lowering it will
+	 most certainly be.  */
+      gcc_assert (cfun->debug_marker_count == 0);
+      cfun->debug_nonbind_markers = false;
+    }
+
   /* If the function falls off the end, we need a null return statement.
      If we've already got one in the return_statements vector, we don't
      need to do anything special.  Otherwise build one by hand.  */
@@ -296,6 +307,20 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
       }
       break;
 
+    case GIMPLE_DEBUG:
+      gcc_checking_assert (cfun->debug_nonbind_markers);
+      /* We can't possibly have debug bind stmts before lowering, we
+	 first emit them when entering SSA.  */
+      gcc_checking_assert (gimple_debug_nonbind_marker_p (stmt));
+      /* Propagate fallthruness.  */
+      /* If the function (e.g. from PCH) had debug stmts, but they're
+	 disabled for this compilation, remove them.  */
+      if (!MAY_HAVE_DEBUG_MARKER_STMTS)
+	gsi_remove (gsi, true);
+      else
+	gsi_next (gsi);
+      return;
+
     case GIMPLE_NOP:
     case GIMPLE_ASM:
     case GIMPLE_ASSIGN:
@@ -503,6 +528,10 @@ lower_try_catch (gimple_stmt_iterator *gsi, struct lower_data *data)
 	cannot_fallthru = false;
       break;
 
+    case GIMPLE_DEBUG:
+      gcc_checking_assert (gimple_debug_begin_stmt_p (stmt));
+      break;
+
     default:
       /* This case represents statements to be executed when an
 	 exception occurs.  Those statements are implicitly followed