[Bug ipa/63416] New: Three calls to empty functions via pointers get folded, but not inlined

[Bug ipa/63416] New: Three calls to empty functions via pointers get folded, but not inlined

[felix.shvaiger at emc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63416

            Bug ID: 63416
           Summary: Three calls to empty functions via pointers get
                    folded, but not inlined
           Product: gcc
           Version: 4.7.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: felix.shvaiger at emc dot com

Created attachment 33620
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33620&action=edit
3 function calls -> folded, not inlined

Missed inlining opportunity.

Issue exists in x86 arch.
4.7, 4.8, 4.9, 5.0 versions (maybe earlier too).
Option: -O2, -O3

If 2 near-empty functions called via pointers, then calls get folded and
inlined.
If 3rd empty function call via pointer added, then all calls get folded, but
not inlined.

Attached test cases (self-contained, no includes):
a1.c -- 3 function calls -> folded, not inlined.

[Bug ipa/63416] Three calls to empty functions via pointers get folded, but not inlined

[felix.shvaiger at emc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63416

--- Comment #1 from Felix Shvaiger <felix.shvaiger at emc dot com> ---
Created attachment 33621
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33621&action=edit
2 function calls -> (for comparison) folded, inlined

[Bug ipa/63416] Three calls to empty functions via pointers get folded, but not inlined

[felix.shvaiger at emc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63416

--- Comment #2 from Felix Shvaiger <felix.shvaiger at emc dot com> ---
Created attachment 33622
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33622&action=edit
disassembly of compiled a1.c -- bad code

[Bug ipa/63416] Three calls to empty functions via pointers get folded, but not inlined

[felix.shvaiger at emc dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63416

--- Comment #3 from Felix Shvaiger <felix.shvaiger at emc dot com> ---
Created attachment 33623
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33623&action=edit
disassembly of compiled a2.c -- good code

[Bug ipa/63416] Three calls to empty functions via pointers get folded, but not inlined

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63416

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Must be sth wrong with size/time estimates.  Honza?