[Bug tree-optimization/65426] New: Recognize byte-swaps when writing to buffers

[Bug tree-optimization/65426] New: Recognize byte-swaps when writing to buffers

[fuz at fuz dot su]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65426

            Bug ID: 65426
           Summary: Recognize byte-swaps when writing to buffers
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fuz at fuz dot su

Created attachment 35036
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35036&action=edit
Various instances of the aforementioned pattern

It would be great if gcc could recognize code like this:

    static inline void
    wm32(uint8_t a[4], uint32_t x)
    {
        a[0] = x >> 24;
        a[1] = x >> 16;
        a[2] = x >>  8;
        a[3] = x >>  0;
    }

and turn it into a single unaligned write (and perhaps a byte swap on platforms
where this is supported). This kind of code appears when one tries to write
marshalling code in a portable fashion.

Attached is a file containing various instances of this pattern.

[Bug tree-optimization/65426] Recognize byte-swaps when writing to buffers

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65426

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This one was implemented or maybe only where the load and stores happen.

[Bug tree-optimization/65426] Recognize byte-swaps when writing to buffers

[fuz at fuz dot su]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65426

--- Comment #2 from Robert Clausecker <fuz at fuz dot su> ---
I tried compiling this code (without static inline) on a trunk (r221432) gcc
and it didn't recognize the pattern. Is there a pattern with the same effect
that gets recognized?

[Bug tree-optimization/65426] Recognize byte-swaps when writing to buffers

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65426

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-03-18
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
stores are not yet supported by the pass.  And I think this bug has a
duplicate.

[Bug tree-optimization/65426] Recognize byte-swaps when writing to buffers

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65426

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |10.0
      Known to fail|                            |7.1.0
      Known to work|                            |10.1.0, 12.0
         Resolution|---                         |FIXED

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
All functions are detected and fixed in GCC 10+. A few were fixed in GCC 8 and
GCC 9 even.