cfgloop.h (struct loop): Document usage of USHRT_MAX for unroll.

	* cfgloop.h (struct loop): Document usage of USHRT_MAX for unroll.
	* loop-unroll.c (decide_unroll_constant_iterations): Implement it.
	(decide_unroll_runtime_iterations): Likewise.
	(decide_unroll_stupid): Likewise.

From-SVN: r255165

gcc/ChangeLog

+2017-11-27  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* cfgloop.h (struct loop): Document usage of USHRT_MAX for unroll.
+	* loop-unroll.c (decide_unroll_constant_iterations): Implement it.
+	(decide_unroll_runtime_iterations): Likewise.
+	(decide_unroll_stupid): Likewise.
+
 2017-11-27  Igor Tsimbalist  <igor.v.tsimbalist@intel.com>
 
 	PR target/83109

gcc/cfgloop.h

@@ -221,9 +221,10 @@ struct GTY ((chain_next ("%h.next"))) loop {
   /* True if the loop is part of an oacc kernels region.  */
   unsigned in_oacc_kernels_region : 1;
 
-  /* The number of times to unroll the loop.  0, means no information
-     given, just do what we always do.  A value of 1, means don't unroll
-     the loop.  */
+  /* The number of times to unroll the loop.  0 means no information given,
+     just do what we always do.  A value of 1 means do not unroll the loop.
+     A value of USHRT_MAX means unroll with no specific unrolling factor.
+     Other values means unroll with the given unrolling factor.  */
   unsigned short unroll;
 
   /* For SIMD loops, this is a unique identifier of the loop, referenced

gcc/loop-unroll.c

@@ -395,7 +395,7 @@ decide_unroll_constant_iterations (struct loop *loop, int flags)
     }
 
   /* Check for an explicit unrolling factor.  */
-  if (loop->unroll)
+  if (loop->unroll > 0 && loop->unroll < USHRT_MAX)
     {
       /* However we cannot unroll completely at the RTL level a loop with
 	 constant number of iterations; it should have been peeled instead.  */
@@ -693,7 +693,7 @@ decide_unroll_runtime_iterations (struct loop *loop, int flags)
   if (targetm.loop_unroll_adjust)
     nunroll = targetm.loop_unroll_adjust (nunroll, loop);
 
-  if (loop->unroll)
+  if (loop->unroll > 0 && loop->unroll < USHRT_MAX)
     nunroll = loop->unroll;
 
   /* Skip big loops.  */
@@ -1177,7 +1177,7 @@ decide_unroll_stupid (struct loop *loop, int flags)
   if (targetm.loop_unroll_adjust)
     nunroll = targetm.loop_unroll_adjust (nunroll, loop);
 
-  if (loop->unroll)
+  if (loop->unroll > 0 && loop->unroll < USHRT_MAX)
     nunroll = loop->unroll;
 
   /* Skip big loops.  */

gcc/testsuite/ChangeLog

+2017-11-27  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/unroll1.ads: Remove alignment clause.
+	* gnat.dg/unroll2.ads: Likewise.
+	* gnat.dg/unroll3.ads: Likewise.
+	* gnat.dg/unroll1.adb: Remove bogus comment terminator.
+	* gnat.dg/unroll2.adb: Likewise.
+	* gnat.dg/unroll3.adb: Likewise.
+	* gnat.dg/unroll4.ad[sb]: New testcase.
+	* gnat.dg/unroll4_pkg.ads: New helper.
+
 2017-11-27  Igor Tsimbalist  <igor.v.tsimbalist@intel.com>
 
 	PR target/83109

gcc/testsuite/gnat.dg/unroll1.adb

@@ -23,5 +23,5 @@ package body Unroll1 is
 
 end Unroll1;
 
--- { dg-final { scan-tree-dump-times "Not unrolling loop .: user didn't want it unrolled completely" 2 "cunrolli" } } */
--- { dg-final { scan-rtl-dump-times "Not unrolling loop, user didn't want it unrolled" 2 "loop2_unroll" } } */
+-- { dg-final { scan-tree-dump-times "Not unrolling loop .: user didn't want it unrolled completely" 2 "cunrolli" } }
+-- { dg-final { scan-rtl-dump-times "Not unrolling loop, user didn't want it unrolled" 2 "loop2_unroll" } }

gcc/testsuite/gnat.dg/unroll1.ads

 package Unroll1 is
 
    type Sarray is array (1 .. 4) of Float;
-   for Sarray'Alignment use 16;
 
    function "+" (X, Y : Sarray) return Sarray;
    procedure Add (X, Y : Sarray; R : out Sarray);

gcc/testsuite/gnat.dg/unroll2.adb

@@ -23,4 +23,4 @@ package body Unroll2 is
 
 end Unroll2;
 
--- { dg-final { scan-tree-dump-times "note: loop with 3 iterations completely unrolled" 2 "cunrolli" } } */
+-- { dg-final { scan-tree-dump-times "note: loop with 3 iterations completely unrolled" 2 "cunrolli" } }

gcc/testsuite/gnat.dg/unroll2.ads

 package Unroll2 is
 
    type Sarray is array (1 .. 4) of Float;
-   for Sarray'Alignment use 16;
 
    function "+" (X, Y : Sarray) return Sarray;
    procedure Add (X, Y : Sarray; R : out Sarray);

gcc/testsuite/gnat.dg/unroll3.adb

@@ -23,4 +23,4 @@ package body Unroll3 is
 
 end Unroll3;
 
--- { dg-final { scan-tree-dump-times "note: loop with 3 iterations completely unrolled" 2 "cunroll" } } */
+-- { dg-final { scan-tree-dump-times "note: loop with 3 iterations completely unrolled" 2 "cunroll" } }

gcc/testsuite/gnat.dg/unroll3.ads

 package Unroll3 is
 
    type Sarray is array (1 .. 4) of Float;
-   for Sarray'Alignment use 16;
 
    function "+" (X, Y : Sarray) return Sarray;
    procedure Add (X, Y : Sarray; R : out Sarray);

gcc/testsuite/gnat.dg/unroll4.adb

+-- { dg-do compile }
+-- { dg-options "-O -fdump-rtl-loop2_unroll-details" }
+
+package body Unroll4 is
+
+   function "+" (X, Y : Sarray) return Sarray is
+      R : Sarray;
+   begin
+      for I in Sarray'Range loop
+         pragma Loop_Optimize (Unroll);
+         R(I) := X(I) + Y(I);
+      end loop;
+      return R;
+   end;
+
+   procedure Add (X, Y : Sarray; R : out Sarray) is
+   begin
+      for I in Sarray'Range loop
+         pragma Loop_Optimize (Unroll);
+         R(I) := X(I) + Y(I);
+      end loop;
+   end;
+
+end Unroll4;
+
+-- { dg-final { scan-rtl-dump-times "note: loop unrolled 7 times" 2 "loop2_unroll" } }

gcc/testsuite/gnat.dg/unroll4.ads

+with Unroll4_Pkg; use Unroll4_Pkg;
+
+package Unroll4 is
+
+   type Sarray is array (1 .. N) of Float;
+
+   function "+" (X, Y : Sarray) return Sarray;
+   procedure Add (X, Y : Sarray; R : out Sarray);
+
+end Unroll4;

gcc/testsuite/gnat.dg/unroll4_pkg.ads

+package Unroll4_Pkg is
+
+   function N return Positive;
+
+end Unroll4_Pkg;