[Bug rtl-optimization/58220] New: [4.9 Regression] Many new failures for SH after rev. 201833

[Bug rtl-optimization/58220] New: [4.9 Regression] Many new failures for SH after rev. 201833

[kkojima at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58220

            Bug ID: 58220
           Summary: [4.9 Regression] Many new failures for SH after rev.
                    201833
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kkojima at gcc dot gnu.org
            Target: sh*-*-*

There are many new execution errors on SH after the revision 201833

r201883 | tejohnson | 2013-08-20 22:29:53 +0900 (Tue, 20 Aug 2013) | 8 lines

The change of final.c:reemit_insn_block_notes for r201883

...
-  for (; insn; insn = next_active_insn (insn))
+  for (; insn; insn = next_insn (insn))
     {
       tree this_block;

+      /* Prevent lexical blocks from straddling section boundaries.  */
+      if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_SWITCH_TEXT_SECTIONS)
+        {
+          for (tree s = cur_block; s != DECL_INITIAL (cfun->decl);
+               s = BLOCK_SUPERCONTEXT (s))
+            {
+              rtx note = emit_note_before (NOTE_INSN_BLOCK_END, insn);
+              NOTE_BLOCK (note) = s;
+              note = emit_note_after (NOTE_INSN_BLOCK_BEG, insn);
+              NOTE_BLOCK (note) = s;
+            }
+        }
+
+      if (!active_insn_p (insn))
+        continue;

uses next_insn and active_insn_p pair instead of next_acrive_insn,
though next_insn handles SEQUENCEs specially:

rtx
next_insn (rtx insn)
{
  if (insn)
    {
      insn = NEXT_INSN (insn);
      if (insn && NONJUMP_INSN_P (insn)
      && GET_CODE (PATTERN (insn)) == SEQUENCE)
    insn = XVECEXP (PATTERN (insn), 0, 0);
    }

  return insn;
}

but next_active_insn does nothing special for SEQUENCEs:

rtx
next_active_insn (rtx insn)
{
  while (insn)
    {
      insn = NEXT_INSN (insn);
      if (insn == 0 || active_insn_p (insn))
    break;
    }

  return insn;
}

It looks now the for loop in reemit_insn_block_notes sees the inside
insn of SEQUENCE, not SEQUENCE insn itself.  The failures went away
with the following one liner.

    * final.c (reemit_insn_block_notes): Use NEXT_INSN instead of
    next_insn.

--- ORIG/trunk/gcc/final.c    2013-08-22 09:43:35.000000000 +0900
+++ trunk/gcc/final.c    2013-08-22 14:36:51.000000000 +0900
@@ -1650,7 +1650,7 @@ reemit_insn_block_notes (void)
   rtx insn, note;

   insn = get_insns ();
-  for (; insn; insn = next_insn (insn))
+  for (; insn; insn = NEXT_INSN (insn))
     {
       tree this_block;

Here is the diff of the generated codes with/without the above patch
for a typical example of failure gcc.c-torture/execute/20000422-1.c
with -Og -g:

--- good.s      2013-08-23 07:47:43.000000000 +0900
+++ bad.s       2013-08-23 07:47:16.000000000 +0900
@@ -27,6 +27,7 @@ main:
 .LBE2:
        .loc 1 17 0
        bra     .L2
+       nop
        mov     #0,r4
 .LVL1:
        .align 1

where SH uses a SEQUENCE for bra instruction and its delayed slot
which should be filled with nop in this case.

[Bug rtl-optimization/58220] [4.9 Regression] Many new failures for SH after rev. 201833

[kkojima at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58220

Kazumoto Kojima <kkojima at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from Kazumoto Kojima <kkojima at gcc dot gnu.org> ---
Fixed at r201941.

[Bug rtl-optimization/58220] [4.9 Regression] Many new failures for SH after rev. 201833

[tejohnson at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58220

--- Comment #2 from tejohnson at gcc dot gnu.org ---
Author: tejohnson
Date: Sat Nov 23 04:30:07 2013
New Revision: 205298

URL: http://gcc.gnu.org/viewcvs?rev=205298&root=gcc&view=rev
Log:
Backport to google/4_8 new sanity checking and some dwarf emission fixes for
-freorder-blocks-and-partition from trunk (r201883, r201941, r202125).

------------------------------------------------------------------------
r201883 | tejohnson | 2013-08-20 06:29:53 -0700 (Tue, 20 Aug 2013) | 8 lines
Changed paths:
   M /trunk/gcc/ChangeLog
   M /trunk/gcc/final.c
   M /trunk/gcc/testsuite/ChangeLog
   A /trunk/gcc/testsuite/g++.dg/tree-prof/pr57451.C

2013-08-20  Teresa Johnson  <tejohnson@google.com>

    PR rtl-optimizations/57451
    * final.c (reemit_insn_block_notes): Prevent lexical blocks
    from crossing split section boundaries.

    * testsuite/g++.dg/tree-prof/pr57451.C: New test.

------------------------------------------------------------------------
------------------------------------------------------------------------
r201941 | tejohnson | 2013-08-23 07:31:06 -0700 (Fri, 23 Aug 2013) | 7 lines
Changed paths:
   M /trunk/gcc/ChangeLog
   M /trunk/gcc/final.c

2013-08-23  Kaz Kojima  <kkojima@gcc.gnu.org>

        PR rtl-optimization/58220
        PR regression/58221
    * final.c (reemit_insn_block_notes): Use NEXT_INSN to
        handle SEQUENCE insns properly.

------------------------------------------------------------------------
------------------------------------------------------------------------
r202125 | tejohnson | 2013-08-30 18:43:33 -0700 (Fri, 30 Aug 2013) | 30 lines
Changed paths:
   M /trunk/gcc/ChangeLog
   M /trunk/gcc/basic-block.h
   M /trunk/gcc/bb-reorder.c
   M /trunk/gcc/cfg.c
   M /trunk/gcc/cfgcleanup.c
   M /trunk/gcc/cfgrtl.c
   M /trunk/gcc/predict.c

This patch sanitizes the partitioning to address issues such as edge
weight insanities that sometimes occur due to upstream optimizations,
and ensures that hot blocks are not dominated by cold blocks. This
needs to be resanitized after certain cfg optimizations that may
cause hot blocks previously reached via both hot and cold paths to
only be reached by cold paths.

The verification code in sanitize_dominator_hotness was contributed by
Steven Bosscher.

2013-08-29  Teresa Johnson  <tejohnson@google.com>
            Steven Bosscher  <steven@gcc.gnu.org>

    * cfgrtl.c (fixup_new_cold_bb): New routine.
    (commit_edge_insertions): Invoke fixup_partitions.
    (find_partition_fixes): New routine.
    (fixup_partitions): Ditto.
    (verify_hot_cold_block_grouping): Update comments.
    (rtl_verify_edges): Invoke find_partition_fixes.
    (rtl_verify_bb_pointers): Update comments.
    (rtl_verify_bb_layout): Ditto.
    * basic-block.h (probably_never_executed_edge_p): Declare.
        (fixup_partitions): Ditto.
    * cfgcleanup.c (try_optimize_cfg): Invoke fixup_partitions.
    * bb-reorder.c (sanitize_hot_paths): New function.
        (find_rarely_executed_basic_blocks_and_crossing_edges): Invoke
        sanitize_hot_paths.
    * predict.c (probably_never_executed_edge_p): New routine.
    * cfg.c (check_bb_profile): Add partition insanity warnings.

------------------------------------------------------------------------

Added:
    branches/google/gcc-4_8/gcc/testsuite/g++.dg/tree-prof/pr57451.C
Modified:
    branches/google/gcc-4_8/gcc/basic-block.h
    branches/google/gcc-4_8/gcc/bb-reorder.c
    branches/google/gcc-4_8/gcc/cfg.c
    branches/google/gcc-4_8/gcc/cfgcleanup.c
    branches/google/gcc-4_8/gcc/cfgrtl.c
    branches/google/gcc-4_8/gcc/final.c
    branches/google/gcc-4_8/gcc/predict.c