[PATCH]middle-end: rejects loops with nonlinear inductions and early breaks [PR113163]

[PATCH]middle-end: rejects loops with nonlinear inductions and early breaks [PR113163]

[Tamar Christina]

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Hi All,

We can't support nonlinear inductions other than neg when vectorizing
early breaks and iteration count is known.

For early break we currently require a peeled epilog but in these cases
we can't compute the remaining values.

Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
tested on cross cc1 for amdgcn-amdhsa and issue fixed.

Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

	PR middle-end/113163
	* tree-vect-loop-manip.cc (vect_can_peel_nonlinear_iv_p):

gcc/testsuite/ChangeLog:

	PR middle-end/113163
	* gcc.target/gcn/pr113163.c: New test.

--- inline copy of patch -- 
diff --git a/gcc/testsuite/gcc.target/gcn/pr113163.c b/gcc/testsuite/gcc.target/gcn/pr113163.c
new file mode 100644
index 0000000000000000000000000000000000000000..99b0fdbaf3a3152ca008b5109abf6e80d8cb3d6a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/gcn/pr113163.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O2 -ftree-vectorize" } */ 
+
+struct _reent { union { struct { char _l64a_buf[8]; } _reent; } _new; };
+static const char R64_ARRAY[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+char *
+_l64a_r (struct _reent *rptr,
+     long value)
+{
+  char *ptr;
+  char *result;
+  int i, index;
+  unsigned long tmp = (unsigned long)value & 0xffffffff;
+  result = 
+          ((
+          rptr
+          )->_new._reent._l64a_buf)
+                               ;
+  ptr = result;
+  for (i = 0; i < 6; ++i)
+    {
+      if (tmp == 0)
+ {
+   *ptr = '\0';
+   break;
+ }
+      *ptr++ = R64_ARRAY[index];
+      tmp >>= 6;
+    }
+}
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 3810983a80c8b989be9fd9a9993642069fd39b99..f1bf43b3731868e7b053c186302fbeaf515be8cf 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -2075,6 +2075,22 @@ vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
       return false;
     }
 
+  /* We can't support partial vectors and early breaks with an induction
+     type other than add or neg since we require the epilog and can't
+     perform the peeling.  PR113163.  */
+  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
+      && LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ()
+      && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
+      && induction_type != vect_step_op_neg)
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "Peeling for epilogue is not supported"
+			 " for nonlinear induction except neg"
+			 " when iteration count is known and early breaks.\n");
+      return false;
+    }
+
   return true;
 }
 




-- 

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diff --git a/gcc/testsuite/gcc.target/gcn/pr113163.c b/gcc/testsuite/gcc.target/gcn/pr113163.c
new file mode 100644
index 0000000000000000000000000000000000000000..99b0fdbaf3a3152ca008b5109abf6e80d8cb3d6a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/gcn/pr113163.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O2 -ftree-vectorize" } */ 
+
+struct _reent { union { struct { char _l64a_buf[8]; } _reent; } _new; };
+static const char R64_ARRAY[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+char *
+_l64a_r (struct _reent *rptr,
+     long value)
+{
+  char *ptr;
+  char *result;
+  int i, index;
+  unsigned long tmp = (unsigned long)value & 0xffffffff;
+  result = 
+          ((
+          rptr
+          )->_new._reent._l64a_buf)
+                               ;
+  ptr = result;
+  for (i = 0; i < 6; ++i)
+    {
+      if (tmp == 0)
+ {
+   *ptr = '\0';
+   break;
+ }
+      *ptr++ = R64_ARRAY[index];
+      tmp >>= 6;
+    }
+}
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 3810983a80c8b989be9fd9a9993642069fd39b99..f1bf43b3731868e7b053c186302fbeaf515be8cf 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -2075,6 +2075,22 @@ vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
       return false;
     }
 
+  /* We can't support partial vectors and early breaks with an induction
+     type other than add or neg since we require the epilog and can't
+     perform the peeling.  PR113163.  */
+  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
+      && LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ()
+      && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
+      && induction_type != vect_step_op_neg)
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "Peeling for epilogue is not supported"
+			 " for nonlinear induction except neg"
+			 " when iteration count is known and early breaks.\n");
+      return false;
+    }
+
   return true;
 }
 

Re: [PATCH]middle-end: rejects loops with nonlinear inductions and early breaks [PR113163]

[Richard Biener]

On Fri, 29 Dec 2023, Tamar Christina wrote:

> Hi All,
> 
> We can't support nonlinear inductions other than neg when vectorizing
> early breaks and iteration count is known.
> 
> For early break we currently require a peeled epilog but in these cases
> we can't compute the remaining values.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> tested on cross cc1 for amdgcn-amdhsa and issue fixed.
> 
> Ok for master?
> 
> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	PR middle-end/113163
> 	* tree-vect-loop-manip.cc (vect_can_peel_nonlinear_iv_p):

Misses sth.

> gcc/testsuite/ChangeLog:
> 
> 	PR middle-end/113163
> 	* gcc.target/gcn/pr113163.c: New test.
> 
> --- inline copy of patch -- 
> diff --git a/gcc/testsuite/gcc.target/gcn/pr113163.c b/gcc/testsuite/gcc.target/gcn/pr113163.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..99b0fdbaf3a3152ca008b5109abf6e80d8cb3d6a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/gcn/pr113163.c
> @@ -0,0 +1,30 @@
> +/* { dg-do compile } */
> +/* { dg-additional-options "-O2 -ftree-vectorize" } */ 
> +
> +struct _reent { union { struct { char _l64a_buf[8]; } _reent; } _new; };
> +static const char R64_ARRAY[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
> +char *
> +_l64a_r (struct _reent *rptr,
> +     long value)
> +{
> +  char *ptr;
> +  char *result;
> +  int i, index;
> +  unsigned long tmp = (unsigned long)value & 0xffffffff;
> +  result = 
> +          ((
> +          rptr
> +          )->_new._reent._l64a_buf)
> +                               ;
> +  ptr = result;
> +  for (i = 0; i < 6; ++i)
> +    {
> +      if (tmp == 0)
> + {
> +   *ptr = '\0';
> +   break;
> + }
> +      *ptr++ = R64_ARRAY[index];
> +      tmp >>= 6;
> +    }
> +}
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index 3810983a80c8b989be9fd9a9993642069fd39b99..f1bf43b3731868e7b053c186302fbeaf515be8cf 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -2075,6 +2075,22 @@ vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
>        return false;
>      }
>  
> +  /* We can't support partial vectors and early breaks with an induction
> +     type other than add or neg since we require the epilog and can't
> +     perform the peeling.  PR113163.  */
> +  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
> +      && LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ()

But why's that only for constant VF?  We might never end up here
with variable VF but the check looks odd ...

OK with that clarified and/or the test removed.

Thanks,
Richard.

> +      && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
> +      && induction_type != vect_step_op_neg)
> +    {
> +      if (dump_enabled_p ())
> +	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +			 "Peeling for epilogue is not supported"
> +			 " for nonlinear induction except neg"
> +			 " when iteration count is known and early breaks.\n");
> +      return false;
> +    }
> +
>    return true;
>  }
>  
> 
> 
> 
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)

RE: [PATCH]middle-end: rejects loops with nonlinear inductions and early breaks [PR113163]

[Tamar Christina]

> -----Original Message-----
> From: Richard Biener <rguenther@suse.de>
> Sent: Monday, January 8, 2024 12:07 PM
> To: Tamar Christina <Tamar.Christina@arm.com>
> Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; jlaw@ventanamicro.com
> Subject: Re: [PATCH]middle-end: rejects loops with nonlinear inductions and early
> breaks [PR113163]
> 
> On Fri, 29 Dec 2023, Tamar Christina wrote:
> 
> > Hi All,
> >
> > We can't support nonlinear inductions other than neg when vectorizing
> > early breaks and iteration count is known.
> >
> > For early break we currently require a peeled epilog but in these cases
> > we can't compute the remaining values.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> > tested on cross cc1 for amdgcn-amdhsa and issue fixed.
> >
> > Ok for master?
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> > 	PR middle-end/113163
> > 	* tree-vect-loop-manip.cc (vect_can_peel_nonlinear_iv_p):
> 
> Misses sth.
> 
> > gcc/testsuite/ChangeLog:
> >
> > 	PR middle-end/113163
> > 	* gcc.target/gcn/pr113163.c: New test.
> >
> > --- inline copy of patch --
> > diff --git a/gcc/testsuite/gcc.target/gcn/pr113163.c
> b/gcc/testsuite/gcc.target/gcn/pr113163.c
> > new file mode 100644
> > index
> 0000000000000000000000000000000000000000..99b0fdbaf3a3152ca008b5
> 109abf6e80d8cb3d6a
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/gcn/pr113163.c
> > @@ -0,0 +1,30 @@
> > +/* { dg-do compile } */
> > +/* { dg-additional-options "-O2 -ftree-vectorize" } */
> > +
> > +struct _reent { union { struct { char _l64a_buf[8]; } _reent; } _new; };
> > +static const char R64_ARRAY[] =
> "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
> ;
> > +char *
> > +_l64a_r (struct _reent *rptr,
> > +     long value)
> > +{
> > +  char *ptr;
> > +  char *result;
> > +  int i, index;
> > +  unsigned long tmp = (unsigned long)value & 0xffffffff;
> > +  result =
> > +          ((
> > +          rptr
> > +          )->_new._reent._l64a_buf)
> > +                               ;
> > +  ptr = result;
> > +  for (i = 0; i < 6; ++i)
> > +    {
> > +      if (tmp == 0)
> > + {
> > +   *ptr = '\0';
> > +   break;
> > + }
> > +      *ptr++ = R64_ARRAY[index];
> > +      tmp >>= 6;
> > +    }
> > +}
> > diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> > index
> 3810983a80c8b989be9fd9a9993642069fd39b99..f1bf43b3731868e7b053c18
> 6302fbeaf515be8cf 100644
> > --- a/gcc/tree-vect-loop-manip.cc
> > +++ b/gcc/tree-vect-loop-manip.cc
> > @@ -2075,6 +2075,22 @@ vect_can_peel_nonlinear_iv_p (loop_vec_info
> loop_vinfo,
> >        return false;
> >      }
> >
> > +  /* We can't support partial vectors and early breaks with an induction
> > +     type other than add or neg since we require the epilog and can't
> > +     perform the peeling.  PR113163.  */
> > +  if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo)
> > +      && LOOP_VINFO_VECT_FACTOR (loop_vinfo).is_constant ()
> 
> But why's that only for constant VF?  We might never end up here
> with variable VF but the check looks odd ...

It's mirroring the condition in vect_gen_vector_loop_niters where we
create step_vector which is not 1. This is the case which causes
niters_vector_mult_vf_var to become a tree var instead.

I'll update the comment to say this.

Thanks,
Tamar
> 
> OK with that clarified and/or the test removed.
> 
> Thanks,
> Richard.
> 
> > +      && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo)
> > +      && induction_type != vect_step_op_neg)
> > +    {
> > +      if (dump_enabled_p ())
> > +	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> > +			 "Peeling for epilogue is not supported"
> > +			 " for nonlinear induction except neg"
> > +			 " when iteration count is known and early breaks.\n");
> > +      return false;
> > +    }
> > +
> >    return true;
> >  }
> >
> >
> >
> >
> >
> >
> 
> --
> Richard Biener <rguenther@suse.de>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)