[Bug tree-optimization/104466] New: Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[Bug tree-optimization/104466] New: Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

            Bug ID: 104466
           Summary: Inlining functions with restrict parameters can
                    inhibit lim (e.g. in 554.roms_r)
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jamborm at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---
              Host: x86_64-linux
            Target: x86_64-linux

We have noticed that a bit more performance can be squeezed out of
554.roms_r benchmark from the SPEC 2017 FPrate suite by using option
-fno-inline-functions-called-once, even at -O2 (but also at -Ofast).
At least one potential reason is that without inlining, loop invariant
motion is able to disambiguate memory references better because of
restrict qualified parameters.  When it cannot, it can be observed by
lim not taking place, at -O2 at least (which in turn affects other
passes).

I tried to create a small-ish reproducer and am attaching the result.
Compile with: -std=legacy -O2 --param max-inline-insns-auto=0 --param
max-inline-insns-single=0  

with and without -fno-inline-functions-called-once and look for lim of
a load from array n in the lim2 dump.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

--- Comment #1 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Created attachment 52393
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52393&action=edit
Test-case

Forgotten testcase

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-02-09
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I will have a look.

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |60712

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Isn't this a dup of bug 60712?


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60712
[Bug 60712] "restrict" qualifier ignored on local variable or after inlining

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Bah, what stupid cut&paste error ...



diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index d434446a997..3e8d2455ba5 100644
--- a/gcc/tree-ssa-alias.cc
+++ b/gcc/tree-ssa-alias.cc
@@ -2420,12 +2420,12 @@ refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool
tbaa_p)
          rbase2 = TREE_OPERAND (rbase2, 0);
     }
   if (rbase1 && rbase2
-      && (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF)
-      && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF)
+      && (TREE_CODE (rbase1) == MEM_REF || TREE_CODE (rbase1) ==
TARGET_MEM_REF)
+      && (TREE_CODE (rbase2) == MEM_REF || TREE_CODE (rbase2) ==
TARGET_MEM_REF)
       /* If the accesses are in the same restrict clique... */
-      && MR_DEPENDENCE_CLIQUE (base1) == MR_DEPENDENCE_CLIQUE (base2)
+      && MR_DEPENDENCE_CLIQUE (rbase1) == MR_DEPENDENCE_CLIQUE (rbase2)
       /* But based on different pointers they do not alias.  */
-      && MR_DEPENDENCE_BASE (base1) != MR_DEPENDENCE_BASE (base2))
+      && MR_DEPENDENCE_BASE (rbase1) != MR_DEPENDENCE_BASE (rbase2))
     return false;

   ind1_p = (TREE_CODE (base1) == MEM_REF

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
So yes, __restrict info _does_ survive inlining.

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
The typos have been there and unnoticed since the original r5-5305 ... :/

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:1b72d456b2a88218ed440655ef0b9e29b4ef63a9

commit r12-7173-g1b72d456b2a88218ed440655ef0b9e29b4ef63a9
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Feb 10 09:03:48 2022 +0100

    tree-optimization/104466 - fix cut&paste error perventing alias
disambiguation

    The following fixes a cut&paste error in disambiguating using restrict
    info.  Instead of using the for this purpose computed rbase1/rbase2
    which preserve MEM_REF bases even when they are based on a decl the
    code performs the check on the bases that drop info for those ...

    2022-02-10  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/104466
            * tree-ssa-alias.cc (refs_may_alias_p_2): Use rbase1/rbase2
            for the MR_DEPENDENCE checks as intended.

            * gfortran.dg/pr104466.f90: New testcase.

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |12.0

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk, I'm considering backporting to GCC 11 eventually.

[Bug tree-optimization/104466] Inlining functions with restrict parameters can inhibit lim (e.g. in 554.roms_r)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104466

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

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

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed for GCC 12, not backporting.