[Bug middle-end/42995] New: [4.3 regression] inline-small-functions does not inline simple delegation calls

[Bug middle-end/42995] New: [4.3 regression] inline-small-functions does not inline simple delegation calls

[matt at use dot net]

Using gcc 4.4.1 under Ubuntu 9.10 on amd64:

main.c:

#include "database.h"

int main()
{
  int my_id = 0;
  int result_for_my_id = get_data_for(my_id);

  switch (result_for_my_id)
  {
    case 0:
      return 666;
    default:
      return -1;
  }
}

database.h:
#include <stdlib.h>

int get_data_for(int id)
{
  return rand();
}

Compiling with:
gcc -O2 main.c -o n

produces this code:
0000000000400380 <main>:
  400380:       48 83 ec 08             sub    rsp,0x8
  400384:       31 ff                   xor    edi,edi
  400386:       e8 e5 ff ff ff          call   400370 <get_data_for>
  40038b:       83 f8 01                cmp    eax,0x1
  40038e:       19 c0                   sbb    eax,eax
  400390:       48 83 c4 08             add    rsp,0x8
  400394:       25 9b 02 00 00          and    eax,0x29b
  400399:       83 e8 01                sub    eax,0x1
  40039c:       c3                      ret
  40039d:       0f 1f 00                nop    DWORD PTR [rax]

Note the 3 bytes of padding after the return. I'm confused why
inline-small-functions does not inline get_data_for. I tried this experiment:
gcc -O2 -finline-functions --param max-inline-insns-auto=20 main.c -o n

which produces this code:
0000000000400380 <main>:
  400380:       48 83 ec 08             sub    rsp,0x8
  400384:       e8 27 02 00 00          call   4005b0 <rand@plt>
  400389:       83 f8 01                cmp    eax,0x1
  40038c:       19 c0                   sbb    eax,eax
  40038e:       48 83 c4 08             add    rsp,0x8
  400392:       25 9b 02 00 00          and    eax,0x29b
  400397:       83 e8 01                sub    eax,0x1
  40039a:       c3                      ret
  40039b:       0f 1f 44 00 00          nop    DWORD PTR [rax+rax*1+0x0]

The padding got larger, but the code is actually smaller. Shouldn't the
heuristic used for inline-small-functions have caused get_data_for() to be
inlined?

This does not appear to be a problem in GCC 4.5.20091228 or 4.3.4.


-- 
           Summary: [4.3 regression] inline-small-functions does not inline
                    simple delegation calls
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: matt at use dot net
 GCC build triplet: x86_64-linux-unknown
  GCC host triplet: x86_64-linux-unknown
GCC target triplet: x86_64-linux-unknown


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995

[Bug middle-end/42995] [4.3 regression] inline-small-functions does not inline simple delegation calls

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2010-02-07 23:03 -------
>The padding got larger,

But the alignment stayed the same. :).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995

[Bug middle-end/42995] [4.4 Regression] inline-small-functions does not inline simple delegation calls

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2010-02-08 10:19 -------
It doesn't inline it because:

Considering inline candidate get_data_for.
Not inlining: code size would grow by 3 insns.

The callee is estimated to have size 16 while the call costs less.  The issue
is a missing check for VOID_TYPE_P in estimate_num_insns which has been
fixed for 4.5.

I have a fix.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
      Known to fail|                            |4.4.3
      Known to work|                            |4.3.4 4.5.0
   Last reconfirmed|0000-00-00 00:00:00         |2010-02-08 10:19:12
               date|                            |
            Summary|[4.3 regression] inline-    |[4.4 Regression] inline-
                   |small-functions does not    |small-functions does not
                   |inline simple delegation    |inline simple delegation
                   |calls                       |calls
   Target Milestone|---                         |4.4.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995

[Bug middle-end/42995] [4.4 Regression] inline-small-functions does not inline simple delegation calls

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2010-02-08 10:41 -------
Subject: Bug 42995

Author: rguenth
Date: Mon Feb  8 10:41:25 2010
New Revision: 156598

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156598
Log:
2010-02-08  Richard Guenther  <rguenther@suse.de>

        PR middle-end/42995
        * gcc.dg/tree-ssa/inline-4.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/inline-4.c
Modified:
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995

[Bug middle-end/42995] [4.4 Regression] inline-small-functions does not inline simple delegation calls

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2010-02-08 14:11 -------
Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995

[Bug middle-end/42995] [4.4 Regression] inline-small-functions does not inline simple delegation calls

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2010-02-08 14:10 -------
Subject: Bug 42995

Author: rguenth
Date: Mon Feb  8 14:10:15 2010
New Revision: 156601

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156601
Log:
2010-02-08  Richard Guenther  <rguenther@suse.de>

        PR middle-end/42995
        * tree-inline.c (estimate_move_cost): Assert we are not called
        with a void type.
        (estimate_num_insns): Do not count the terminating void_type_node
        of a function argument type list.

        Backport from mainline:
        2010-01-06  Richard Guenther  <rguenther@suse.de>

        * ipa-inline.c (cgraph_decide_inlining_incrementally): Do
        not inline regular functions into always-inline functions.

        2010-01-05  Martin Jambor  <mjambor@suse.cz>

        PR tree-optimization/42462
        * ipa-inline.c (compute_inline_parameters): Pass node->decl instead of
        current_function_decl to helper functions and macros.

        * gcc.dg/tree-ssa/inline-4.c: New testcase.
        * gcc.dg/Wunreachable-2.c: Remove.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/tree-ssa/inline-4.c
Removed:
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/Wunreachable-2.c
Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/ipa-inline.c
    branches/gcc-4_4-branch/gcc/tree-inline.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42995