On Thu, Mar 19, 2015 at 9:38 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
> On Thu, Mar 19, 2015 at 8:44 AM, Jakub Jelinek <ja...@redhat.com> wrote:
>> On Wed, Mar 18, 2015 at 08:00:33PM +0100, Uros Bizjak wrote:
>>> 2015-03-18 Uros Bizjak <ubiz...@gmail.com>
>>>
>>> PR rtl-optimization/60851
>>> * recog.c (constrain_operands): Accept a pseudo register before reload
>>> for LRA enabled targets.
>
>> As the two adjacent conditions are mostly the same, perhaps it might be
>> better written as
>> || ((/* Before reload, accept a pseudo, since
>> LRA can turn it into a mem.
>> (targetm.lra_p () && strict < 0)
>> /* During reload, accept a pseudo. */
>> || reload_in_progress)
>> && REG_P (op)
>> && REGNO (op) >= FIRST_PSEUDO_REGISTER)))
>>
>> or put REG_P && REGNO checks first and only then test when.
>
> Yeah, I thought about this particular CSE a bit. But since these are
> two conceptually different conditions, and the formatting (and
> comments) just didn't fit into available space, I wrote it this way.
> IMO, it is more readable, better follows the intended logic, and
> avoids even more indents.
>
> Also, I am pretty sure that any decent compiler can CSE this part on its own.
>
> However, the condition can be slightly improved by rewriting it to:
>
> /* Before reload, accept a pseudo,
> since LRA can turn it into a mem. */
> || (strict < 0 && targetm.lra_p () && REG_P (op)
> && REGNO (op) >= FIRST_PSEUDO_REGISTER)
>
> so, we have cheaper tests in the front to shortcut more expensive tests later.
>
>> For 4.9 backport, please wait a few days after it goes into the trunk.
Attached is the 4.9 branch version of the patch. There were
substantial cleanups [1] in this area for 5.0, so comparing to trunk
version, the patch includes two more places that have to be changed.
Patch was bootstrapped and regression tested on x86_64-linux-gnu
{,-m32}. If there are no objections, I plan to commit this version to
the branch in a couple of days.
[1] https://gcc.gnu.org/ml/gcc-patches/2014-06/msg00530.html
Uros.
Index: testsuite/gcc.target/i386/pr60851.c
===================================================================
--- testsuite/gcc.target/i386/pr60851.c (revision 0)
+++ testsuite/gcc.target/i386/pr60851.c (revision 0)
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -flive-range-shrinkage -mtune=bdver4
-mdispatch-scheduler" } */
+
+long double ld (char c)
+{
+ return c;
+}
Index: recog.c
===================================================================
--- recog.c (revision 221587)
+++ recog.c (working copy)
@@ -2627,9 +2627,14 @@ constrain_operands (int strict)
break;
win = 1;
}
- /* Before reload, accept what reload can turn into mem. */
+ /* Before reload, accept what reload can turn into a mem. */
else if (strict < 0 && CONSTANT_P (op))
win = 1;
+ /* Before reload, accept a pseudo,
+ since LRA can turn it into a mem. */
+ else if (strict < 0 && targetm.lra_p () && REG_P (op)
+ && REGNO (op) >= FIRST_PSEUDO_REGISTER)
+ win = 1;
/* During reload, accept a pseudo */
else if (reload_in_progress && REG_P (op)
&& REGNO (op) >= FIRST_PSEUDO_REGISTER)
@@ -2708,6 +2713,10 @@ constrain_operands (int strict)
/* Before reload, accept what reload can handle. */
|| (strict < 0
&& (CONSTANT_P (op) || MEM_P (op)))
+ /* Before reload, accept a pseudo,
+ since LRA can turn it into a mem. */
+ || (strict < 0 && targetm.lra_p () && REG_P (op)
+ && REGNO (op) >= FIRST_PSEUDO_REGISTER)
/* During reload, accept a pseudo */
|| (reload_in_progress && REG_P (op)
&& REGNO (op) >= FIRST_PSEUDO_REGISTER))
@@ -2739,8 +2748,12 @@ constrain_operands (int strict)
/* Every memory operand can be reloaded to fit. */
&& ((strict < 0 && MEM_P (op))
/* Before reload, accept what reload can turn
- into mem. */
+ into a mem. */
|| (strict < 0 && CONSTANT_P (op))
+ /* Before reload, accept a pseudo,
+ since LRA can turn it into a mem. */
+ || (strict < 0 && targetm.lra_p () && REG_P (op)
+ && REGNO (op) >= FIRST_PSEUDO_REGISTER)
/* During reload, accept a pseudo */
|| (reload_in_progress && REG_P (op)
&& REGNO (op) >= FIRST_PSEUDO_REGISTER)))
