[Bug c/28405] New: 4.x code generation regression relative to 3.4.6

[Bug c/28405] New: 4.x code generation regression relative to 3.4.6

[vda dot linux at googlemail dot com]

gcc 3.4.x generates a bit suboptimal code on the below fragment.
gcc 4.x generates code which is a bit more suboptimal.

unsigned v;
void g(unsigned A)
/* gcc -O2 -fomit-frame-pointer -S:
gcc-3.4.3, 3.4.6:
        movl    $-858993459, %eax
        mull    4(%esp)
        movl    %edx, %eax      // huh?
        shrl    $3, %eax
        movl    %eax, v
        ret
gcc-4.0.0,4.1.1:
        movl    $-858993459, %eax
        mull    4(%esp)
        movl    %edx, %eax      // huh?
        xorl    %edx, %edx      // huh??
        shrl    $3, %eax
        movl    %eax, v
        ret
*/
{
        v = (A * 3435973837ULL) >> 35;
}


-- 
           Summary: 4.x code generation regression relative to 3.4.6
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: vda dot linux at googlemail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28405

[Bug target/28405] 4.x code generation regression relative to 3.4.6

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-07-17 09:16 -------
As far as I can tell this is a target issue of splitting too late.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
 GCC target triplet|                            |i686-apple-darwin8.5.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28405

[Bug target/28405] 4.x code generation regression relative to 3.4.6

[lopezibanez at gmail dot com]

------- Comment #2 from lopezibanez at gmail dot com  2006-09-20 22:04 -------
I can confirm this in a recent build of GCC: (GNU) 4.2.0 20060913
(experimental) on i686-pc-linux-gnu.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28405

[Bug target/28405] 4.x code generation regression relative to 3.4.6

[steven at gcc dot gnu dot org]

------- Comment #3 from steven at gcc dot gnu dot org  2006-09-20 22:19 -------


*** This bug has been marked as a duplicate of 24929 ***


-- 

steven at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28405