[SFN] not-quite-boilerplate changes in preparation to introduce nonbind markers

This patch adjusts numerous parts of the compiler that would
malfunction should they find debug markers at points where they may be
introduced.  The changes purport to allow the compiler to pass
bootstrap-debug-lean (-fcompare-debug in stage3) at various
optimization levels, as well as bootstrap-debug-lib (-fcompare-debug
for target libraries), even after the compiler is changed so that
debug markers are introduced in code streams at spots where earlier
debug stmts, insns and notes wouldn't normally appear.

This patch depends on an earlier SFN boilerplate patch, and on another
SFN patch that introduces new RTL insn-walking functions.

for  gcc/ChangeLog

	* cfgcleanup.c (delete_unreachable_blocks): Use alternate
	block removal order if MAY_HAVE_DEBUG_BIND_INSNS.
	* cfgexpand.c (label_rtx_for_bb): Skip debug insns.
	* cfgrtl.c (try_redirect_by_replacing_jump): Skip debug insns.
	(rtl_tidy_fallthru_edge): Likewise.
	(rtl_verify_fallthru): Likewise.
	(rtl_verify_bb_layout): Likewise.
	(skip_insns_after_block): Likewise.
	(duplicate_insn_chain): Use DEBUG_BIND_INSN_P.
	* dwarf2out.c: Include print-rtl.h.
	(dwarf2out_next_real_insn): New.
	(dwarf2out_var_location): Call it.  Disregard begin stmt markers.
	Dump debug binds in asm comments.
	* gimple-iterator.c (gimple_find_edge_insert_loc): Skip debug stmts.
	* gimple-iterator.h (gsi_start_bb_nondebug): Remove; adjust
	callers to use gsi_start_nondebug_bb instead.
	(gsi_after_labels): Skip gimple debug stmts.
	(gsi_start_nondebug): New.
	* gimple-loop-interchange.c (find_deps_in_bb_for_stmt): Adjust.
	(proper_loop_form_for_interchange): Adjust.
	* gimple-low.c (gimple_seq_may_fallthru): Take last nondebug stmt.
	* gimple.h (gimple_seq_last_nondebug_stmt): New.
	* gimplify.c (last_stmt_in_scope): Skip debug stmts.
	(collect_fallthrough_labels): Likewise.
	(should_warn_for_implicit_fallthrough): Likewise.
	(warn_implicit_fallthrough_r): Likewise.
	(expand_FALLTHROUGH_r): Likewise.
	* graphite-isl-ast-to-gimple.c (gsi_insert_earliest): Adjust.
	(graphite_copy_stmts_from_block): Skip nonbind markers.
	* haifa-sched.c (sched_extend_bb): Skip debug insns.
	* ipa-icf-gimple.c (func_checker::compare_bb): Adjust.
	* jump.c (clean_barriers): Skip debug insns.
	* omp-expand.c (expand_parallel_call): Skip debug insns.
	(expand_task_call): Likewise.
	(remove_exit_barrier): Likewise.
	(expand_omp_taskreg): Likewise.
	(expand_omp_for_init_counts): Likewise.
	(expand_omp_for_generic): Likewise.
	(expand_omp_for_static_nochunk): Likewise.
	(expand_omp_for_static_chunk): Likewise.
	(expand_omp_simd): Likewise.
	(expand_omp_taskloop_for_outer): Likewise.
	(expand_omp_taskloop_for_inner): Likewise.
	(expand_oacc_for): Likewise.
	(expand_omp_sections): Likewise.
	(expand_omp_single): Likewise.
	(expand_omp_synch): Likewise.
	(expand_omp_atomic_load): Likewise.
	(expand_omp_atomic_store): Likewise.
	(expand_omp_atomic_fetch_op): Likewise.
	(expand_omp_atomic_pipeline): Likewise.
	(expand_omp_atomic_mutex): Likewise.
	(expand_omp_target): Likewise.
	(grid_expand_omp_for_loop): Likewise.
	(grid_expand_target_grid_body): Likewise.
	(build_omp_regions_1): Likewise.
	* omp-low.c (check_combined_parallel): Skip debug stmts.
	* postreload.c (fixup_debug_insns): Skip nonbind debug insns.
	* regcprop.c (find_oldest_value_reg): Ensure REGNO is not a pseudo.
	* sese.c (sese_trivially_empty_bb_p): Call is_gimple_debug in
	test.
	* tree-cfg.c (make_blobs_1): Skip debug stmts.
	(make_edges): Likewise.
	(cleanup_dead_labels): Likewise.
	(gimple_can_merge_blocks_p): Likewise.
	(stmt_starts_bb_p): Likewise.
	(gimple_block_label): Likewise.
	(gimple_redirect_edge_and_branch): Likewise.
	* tree-cfgcleanup.c (remove_forwarder_block): Rearrange skipping
	of debug stmts.
	(execute_cleanup_cfg_post_optimizing): Dump enumerated decls with
	TDF_SLIM.
	* tree-pretty-print (print_declaration): Omit initializer in slim
	dumps.
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Mark begin stmt
	markers.
	(eliminate_unnecessary_stmts): Stabilize block removal order.
	* tree-ssa-tail-merge.c (find_duplicate): Skip debug stmts.
	* var-tracking.c (get_first_insn): New.
	(vt_emit_notes): Call it.
	(vt_initialize): Walk any insns before the first BB.
	(delete_debug_insns): Likewise.

From-SVN: r255566

1 files changed, 50 insertions, 4 deletions

diff --git a/gcc/var-tracking.c b/gcc/var-tracking.c
index 33bcca7..b324a2c 100644
--- a/gcc/var-tracking.c
+++ b/gcc/var-tracking.c
@@ -9479,6 +9479,24 @@ emit_notes_in_bb (basic_block bb, dataflow_set *set)
     }
 }
 
+/* Return BB's head, unless BB is the block that succeeds ENTRY_BLOCK,
+   in which case it searches back from BB's head for the very first
+   insn.  Use [get_first_insn (bb), BB_HEAD (bb->next_bb)[ as a range
+   to iterate over all insns of a function while iterating over its
+   BBs.  */
+
+static rtx_insn *
+get_first_insn (basic_block bb)
+{
+  rtx_insn *insn = BB_HEAD (bb);
+
+  if (bb->prev_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+    while (rtx_insn *prev = PREV_INSN (insn))
+      insn = prev;
+
+  return insn;
+}
+
 /* Emit notes for the whole function.  */
 
 static void
@@ -9507,7 +9525,8 @@ vt_emit_notes (void)
     {
       /* Emit the notes for changes of variable locations between two
 	 subsequent basic blocks.  */
-      emit_notes_for_differences (BB_HEAD (bb), &cur, &VTI (bb)->in);
+      emit_notes_for_differences (get_first_insn (bb),
+				  &cur, &VTI (bb)->in);
 
       if (MAY_HAVE_DEBUG_BIND_INSNS)
 	local_get_addr_cache = new hash_map<rtx, rtx>;
@@ -10103,11 +10122,34 @@ vt_initialize (void)
 	{
 	  HOST_WIDE_INT offset = VTI (bb)->out.stack_adjust;
 	  VTI (bb)->out.stack_adjust = VTI (bb)->in.stack_adjust;
-	  for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
-	       insn = NEXT_INSN (insn))
+
+	  /* If we are walking the first basic block, walk any HEADER
+	     insns that might be before it too.  Unfortunately,
+	     BB_HEADER and BB_FOOTER are not set while we run this
+	     pass.  */
+	  insn = get_first_insn (bb);
+	  for (rtx_insn *next;
+	       insn != BB_HEAD (bb->next_bb)
+		 ? next = NEXT_INSN (insn), true : false;
+	       insn = next)
 	    {
 	      if (INSN_P (insn))
 		{
+		  basic_block save_bb = BLOCK_FOR_INSN (insn);
+		  if (!BLOCK_FOR_INSN (insn))
+		    {
+		      BLOCK_FOR_INSN (insn) = bb;
+		      gcc_assert (DEBUG_INSN_P (insn));
+		      /* Reset debug insns between basic blocks.
+			 Their location is not reliable, because they
+			 were probably not maintained up to date.  */
+		      if (DEBUG_BIND_INSN_P (insn))
+			INSN_VAR_LOCATION_LOC (insn)
+			  = gen_rtx_UNKNOWN_VAR_LOC ();
+		    }
+		  else
+		    gcc_assert (BLOCK_FOR_INSN (insn) == bb);
+
 		  if (!frame_pointer_needed)
 		    {
 		      insn_stack_adjust_offset_pre_post (insn, &pre, &post);
@@ -10175,6 +10217,7 @@ vt_initialize (void)
 			    }
 			}
 		    }
+		  BLOCK_FOR_INSN (insn) = save_bb;
 		}
 	    }
 	  gcc_assert (offset == VTI (bb)->out.stack_adjust);
@@ -10215,7 +10258,10 @@ delete_debug_insns (void)
 
   FOR_EACH_BB_FN (bb, cfun)
     {
-      FOR_BB_INSNS_SAFE (bb, insn, next)
+      for (insn = get_first_insn (bb);
+	   insn != BB_HEAD (bb->next_bb)
+	     ? next = NEXT_INSN (insn), true : false;
+	   insn = next)
 	if (DEBUG_INSN_P (insn))
 	  {
 	    tree decl = INSN_VAR_LOCATION_DECL (insn);