[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

--- Comment #8 from Andrew Pinski  ---
(In reply to Andrew Pinski from comment #6)
> here is a testcase where DOM does not mess with the loop but we should still
> be able to sink the function out and do when adding  -fno-tree-pre:
> 
> int f(int n, int t) {
>   int i,j=0;
>   if (t >=31 || t < 0)  return 100;
> 
>   for (i = 0; i < t; i++) {
> j = __builtin_ffs(i);
>   }
>   return j;
> }

Note in GCC 12+, you need  -fno-tree-vectorize to get the bad behavior back.

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[drraph at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

--- Comment #7 from Raphael C  ---
As of gcc 8 this returns:

f(int):
mov eax, 1
ret

I think this can be closed as resolved now.

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

Andrew Pinski  changed:

   What|Removed |Added

 Status|RESOLVED|NEW
   Severity|normal  |enhancement
 Resolution|FIXED   |---

--- Comment #6 from Andrew Pinski  ---
So this is actually still broken in the sense if we turn off dominator
optimizations (-fno-tree-dominator-opts), the problem with PRE and sink
interaction comes into play still.

The improvement came in via r8-2694 which in fact added
-fno-tree-dominator-opts to gcc.dg/tree-ssa/ssa-sink-16.c .
Note DOM actually does the sinking rather than the rotating of the loop.

here is a testcase where DOM does not mess with the loop but we should still be
able to sink the function out and do when adding  -fno-tree-pre:

int f(int n, int t) {
  int i,j=0;
  if (t >=31 || t < 0)  return 100;

  for (i = 0; i < t; i++) {
j = __builtin_ffs(i);
  }
  return j;
}

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[drraph at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

--- Comment #5 from Raphael C  ---
I can confirm you now get

f:
mov eax, 1
ret

with gcc 8 onwards.

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

Jeffrey A. Law  changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 CC||law at redhat dot com
 Resolution|--- |FIXED

--- Comment #4 from Jeffrey A. Law  ---
I was trolling through BZs related to an issue I'd recently looked at.  I
stumbled over this along the way.  AFAICT this is fixed on the trunk.  In the
.optimized dump we get the desired:

;; Function f (f, funcdef_no=0, decl_uid=1908, cgraph_uid=1, symbol_order=0)

f (int n)
{
   [local count: 32534378]:
  return 1;

}

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

--- Comment #3 from Richard Biener  ---
Ok, so sinking now handles calls but the testcase still isn't fixed because PRE
interferes (testsuite disables PRE).

Still mine.

[Bug tree-optimization/79201] missed optimization: sinking doesn't handle calls, swap PRE and sinking

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79201

--- Comment #2 from Richard Biener  ---
Author: rguenth
Date: Tue Apr 25 09:26:37 2017
New Revision: 247159

URL: https://gcc.gnu.org/viewcvs?rev=247159=gcc=rev
Log:
2017-04-25  Richard Biener  

PR tree-optimization/79201
* tree-ssa-sink.c (statement_sink_location): Handle calls.

* gcc.dg/tree-ssa/ssa-sink-16.c: New testcase.
* gcc.target/i386/pr22152.c: Disable sinking.

Added:
trunk/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-16.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/testsuite/gcc.target/i386/pr22152.c
trunk/gcc/tree-ssa-sink.c