Re: Handle data dependence relations with different bases

[Richard Sandiford <richard.sandiford@linaro.org>]

Eric Botcazou <ebotcazou@adacore.com> writes:
> [Sorry for missing the previous messages]
>
>> Thanks.  Just been retesting, and I think I must have forgotten
>> to include Ada last time.  It turns out that the patch causes a dg-scan
>> regression in gnat.dg/vect17.adb, because we now think that if the
>> array RECORD_TYPEs *do* alias in:
>> 
>>    procedure Add (X, Y : aliased Sarray; R : aliased out Sarray) is
>>    begin
>>       for I in Sarray'Range loop
>>          R(I) := X(I) + Y(I);
>>       end loop;
>>    end;
>> 
>> then the dependence distance must be zero.  Eric, does that hold true
>> for Ada?  I.e. if X and R (or Y and R) alias, must it be the case that
>> X(I) can only alias R(I) and not for example R(I-1) or R(I+1)?
>
> Yes, I'd think so (even without the artificial RECORD_TYPE around the arrays).

Good!

>> 2017-06-07  Richard Sandiford  <richard.sandiford@linaro.org>
>> 
>> gcc/testsuite/
>> 	* gnat.dg/vect17.ads (Sarray): Increase range to 1 .. 5.
>> 	* gnat.dg/vect17.adb (Add): Create a dependence distance of 1
>> 	when X = R or Y = R.
>
> I think that you need to modify vect15 and vect16 the same way.

Ah, yeah.  And doing that shows that I'd not handled safelen for
DDR_COULD_BE_INDEPENDENT_P.  I've fixed that locally.

How does this look?  Tested on x86_64-linux-gnu both without the
vectoriser changes and with the fixed vectoriser patch.

Thanks,
Richard


2017-07-07  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/testsuite/
	* gnat.dg/vect15.ads (Sarray): Increase range to 1 .. 5.
	* gnat.dg/vect16.ads (Sarray): Likewise.
	* gnat.dg/vect17.ads (Sarray): Likewise.
	* gnat.dg/vect15.adb (Add): Create a dependence distance of 1.
	* gnat.dg/vect16.adb (Add): Likewise.
	* gnat.dg/vect17.adb (Add): Likewise.

Index: gcc/testsuite/gnat.dg/vect15.ads
===================================================================
--- gcc/testsuite/gnat.dg/vect15.ads	2015-10-14 14:58:56.000000000 +0100
+++ gcc/testsuite/gnat.dg/vect15.ads	2017-07-07 13:12:51.509540701 +0100
@@ -1,6 +1,6 @@
 package Vect15 is
 
-   type Sarray is array (1 .. 4) of Long_Float;
+   type Sarray is array (1 .. 5) of Long_Float;
    for Sarray'Alignment use 16;
 
    procedure Add (X, Y : Sarray; R : out Sarray);
Index: gcc/testsuite/gnat.dg/vect16.ads
===================================================================
--- gcc/testsuite/gnat.dg/vect16.ads	2015-10-14 14:58:56.000000000 +0100
+++ gcc/testsuite/gnat.dg/vect16.ads	2017-07-07 13:12:51.511540636 +0100
@@ -1,6 +1,6 @@
 package Vect16 is
 
-   type Sarray is array (1 .. 4) of Long_Float;
+   type Sarray is array (1 .. 5) of Long_Float;
    for Sarray'Alignment use 16;
 
    procedure Add_Sub (X, Y : Sarray; R,S : out Sarray);
Index: gcc/testsuite/gnat.dg/vect17.ads
===================================================================
--- gcc/testsuite/gnat.dg/vect17.ads	2017-06-07 22:13:29.692531472 +0100
+++ gcc/testsuite/gnat.dg/vect17.ads	2017-07-07 13:12:51.514540538 +0100
@@ -1,6 +1,6 @@
 package Vect17 is
 
-   type Sarray is array (1 .. 4) of Long_Float;
+   type Sarray is array (1 .. 5) of Long_Float;
    for Sarray'Alignment use 16;
 
    procedure Add (X, Y : aliased Sarray; R : aliased out Sarray);
Index: gcc/testsuite/gnat.dg/vect15.adb
===================================================================
--- gcc/testsuite/gnat.dg/vect15.adb	2015-10-14 14:58:56.000000000 +0100
+++ gcc/testsuite/gnat.dg/vect15.adb	2017-07-07 13:12:51.509540701 +0100
@@ -5,8 +5,9 @@ package body Vect15 is
 
    procedure Add (X, Y : Sarray; R : out Sarray) is
    begin
-      for I in Sarray'Range loop
-         R(I) := X(I) + Y(I);
+      R(1) := X(5) + Y(5);
+      for I in 1 .. 4 loop
+         R(I + 1) := X(I) + Y(I);
       end loop;
    end;
 
Index: gcc/testsuite/gnat.dg/vect16.adb
===================================================================
--- gcc/testsuite/gnat.dg/vect16.adb	2015-10-14 14:58:56.000000000 +0100
+++ gcc/testsuite/gnat.dg/vect16.adb	2017-07-07 13:12:51.510540669 +0100
@@ -5,9 +5,11 @@ package body Vect16 is
 
    procedure Add_Sub (X, Y : Sarray; R,S : out Sarray) is
    begin
-      for I in Sarray'Range loop
-         R(I) := X(I) + Y(I);
-         S(I) := X(I) - Y(I);
+      R(1) := X(5) + Y(5);
+      S(1) := X(5) - Y(5);
+      for I in 1 .. 4 loop
+         R(I + 1) := X(I) + Y(I);
+         S(I + 1) := X(I) - Y(I);
       end loop;
    end;
 
Index: gcc/testsuite/gnat.dg/vect17.adb
===================================================================
--- gcc/testsuite/gnat.dg/vect17.adb	2017-06-07 22:13:29.692531472 +0100
+++ gcc/testsuite/gnat.dg/vect17.adb	2017-07-07 13:12:51.512540603 +0100
@@ -5,8 +5,9 @@ package body Vect17 is
 
    procedure Add (X, Y : aliased Sarray; R : aliased out Sarray) is
    begin
-      for I in Sarray'Range loop
-         R(I) := X(I) + Y(I);
+      R(1) := X(5) + Y(5);
+      for I in 1 .. 4 loop
+         R(I + 1) := X(I) + Y(I);
       end loop;
    end;