Re: [PATCH] Fix PR81719

[Richard Biener]

On Tue, 8 Aug 2017, Bin.Cheng wrote:

> On Tue, Aug 8, 2017 at 1:20 PM, Richard Biener  wrote:
> >
> > The following improves niter analysis for range-based for loops
> > by handling ADDR_EXPR in expand_simple_operations.
> >
> > Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
> >
> > Richard.
> >
> > 2017-08-08  Richard Biener  
> >
> > PR middle-end/81719
> > * tree-ssa-loop-niter.c: Include tree-dfa.h.
> > (expand_simple_operations): Also look through ADDR_EXPRs with
> > MEM_REF bases treating them as POINTER_PLUS_EXPR.
> >
> > * g++.dg/tree-ssa/pr81719.C: New testcase.
> >
> > Index: gcc/tree-ssa-loop-niter.c
> > ===
> > *** gcc/tree-ssa-loop-niter.c   (revision 250813)
> > --- gcc/tree-ssa-loop-niter.c   (working copy)
> > *** along with GCC; see the file COPYING3.
> > *** 42,47 
> > --- 42,48 
> >   #include "tree-chrec.h"
> >   #include "tree-scalar-evolution.h"
> >   #include "params.h"
> > + #include "tree-dfa.h"
> >
> >
> >   /* The maximum number of dominator BBs we search for conditions
> > *** expand_simple_operations (tree expr, tre
> > *** 1980,1985 
> > --- 1981,2001 
> >
> > if (code == SSA_NAME)
> > return expand_simple_operations (e, stop);
> > +   else if (code == ADDR_EXPR)
> > +   {
> > + HOST_WIDE_INT offset;
> > + tree base = get_addr_base_and_unit_offset (TREE_OPERAND (e, 0),
> > +);
> > + if (base
> > + && TREE_CODE (base) == MEM_REF)
> > +   {
> > + ee = expand_simple_operations (TREE_OPERAND (base, 0), stop);
> > + return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (expr), ee,
> > + wide_int_to_tree (sizetype,
> > +   mem_ref_offset (base)
> > +   + offset));
> > +   }
> > +   }
> >
> > return expr;
> >   }
> There are various places we need to look into ADDR_EXPR (MEM_REF), is
> it possible/beneficial to generally simplify _REF[base + offset]?

Not sure - we already do this to some extent in pass_laddress, but
only for the non-constant offset case.

Note for the testcase we have [ptr + 8] and >foo.bar.

Richard.

> Thanks,
> bin
> > Index: gcc/testsuite/g++.dg/tree-ssa/pr81719.C
> > ===
> > *** gcc/testsuite/g++.dg/tree-ssa/pr81719.C (nonexistent)
> > --- gcc/testsuite/g++.dg/tree-ssa/pr81719.C (working copy)
> > ***
> > *** 0 
> > --- 1,24 
> > + /* { dg-do compile { target c++11 } } */
> > + /* { dg-options "-O3 -fdump-tree-optimized" } */
> > +
> > + typedef int Items[2];
> > +
> > + struct ItemArray
> > + {
> > +   Items items;
> > +   int sum_x2() const;
> > + };
> > +
> > + int ItemArray::sum_x2() const
> > + {
> > +   int total = 0;
> > +   for (int item : items)
> > + {
> > +   total += item;
> > + }
> > +   return total;
> > + }
> > +
> > + /* We should be able to compute the number of iterations to two, unroll
> > +the loop and end up with a single basic-block in sum_x2.  */
> > + /* { dg-final { scan-tree-dump-times "bb" 1 "optimized" } } */
> 
> 

-- 
Richard Biener 
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 
21284 (AG Nuernberg)

Re: [PATCH] Fix PR81719

[Bin.Cheng]

On Tue, Aug 8, 2017 at 1:20 PM, Richard Biener  wrote:
>
> The following improves niter analysis for range-based for loops
> by handling ADDR_EXPR in expand_simple_operations.
>
> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
>
> Richard.
>
> 2017-08-08  Richard Biener  
>
> PR middle-end/81719
> * tree-ssa-loop-niter.c: Include tree-dfa.h.
> (expand_simple_operations): Also look through ADDR_EXPRs with
> MEM_REF bases treating them as POINTER_PLUS_EXPR.
>
> * g++.dg/tree-ssa/pr81719.C: New testcase.
>
> Index: gcc/tree-ssa-loop-niter.c
> ===
> *** gcc/tree-ssa-loop-niter.c   (revision 250813)
> --- gcc/tree-ssa-loop-niter.c   (working copy)
> *** along with GCC; see the file COPYING3.
> *** 42,47 
> --- 42,48 
>   #include "tree-chrec.h"
>   #include "tree-scalar-evolution.h"
>   #include "params.h"
> + #include "tree-dfa.h"
>
>
>   /* The maximum number of dominator BBs we search for conditions
> *** expand_simple_operations (tree expr, tre
> *** 1980,1985 
> --- 1981,2001 
>
> if (code == SSA_NAME)
> return expand_simple_operations (e, stop);
> +   else if (code == ADDR_EXPR)
> +   {
> + HOST_WIDE_INT offset;
> + tree base = get_addr_base_and_unit_offset (TREE_OPERAND (e, 0),
> +);
> + if (base
> + && TREE_CODE (base) == MEM_REF)
> +   {
> + ee = expand_simple_operations (TREE_OPERAND (base, 0), stop);
> + return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (expr), ee,
> + wide_int_to_tree (sizetype,
> +   mem_ref_offset (base)
> +   + offset));
> +   }
> +   }
>
> return expr;
>   }
There are various places we need to look into ADDR_EXPR (MEM_REF), is
it possible/beneficial to generally simplify _REF[base + offset]?

Thanks,
bin
> Index: gcc/testsuite/g++.dg/tree-ssa/pr81719.C
> ===
> *** gcc/testsuite/g++.dg/tree-ssa/pr81719.C (nonexistent)
> --- gcc/testsuite/g++.dg/tree-ssa/pr81719.C (working copy)
> ***
> *** 0 
> --- 1,24 
> + /* { dg-do compile { target c++11 } } */
> + /* { dg-options "-O3 -fdump-tree-optimized" } */
> +
> + typedef int Items[2];
> +
> + struct ItemArray
> + {
> +   Items items;
> +   int sum_x2() const;
> + };
> +
> + int ItemArray::sum_x2() const
> + {
> +   int total = 0;
> +   for (int item : items)
> + {
> +   total += item;
> + }
> +   return total;
> + }
> +
> + /* We should be able to compute the number of iterations to two, unroll
> +the loop and end up with a single basic-block in sum_x2.  */
> + /* { dg-final { scan-tree-dump-times "bb" 1 "optimized" } } */

[PATCH] Fix PR81719

[Richard Biener]

The following improves niter analysis for range-based for loops
by handling ADDR_EXPR in expand_simple_operations.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2017-08-08  Richard Biener  

PR middle-end/81719
* tree-ssa-loop-niter.c: Include tree-dfa.h.
(expand_simple_operations): Also look through ADDR_EXPRs with
MEM_REF bases treating them as POINTER_PLUS_EXPR.

* g++.dg/tree-ssa/pr81719.C: New testcase.

Index: gcc/tree-ssa-loop-niter.c
===
*** gcc/tree-ssa-loop-niter.c   (revision 250813)
--- gcc/tree-ssa-loop-niter.c   (working copy)
*** along with GCC; see the file COPYING3.
*** 42,47 
--- 42,48 
  #include "tree-chrec.h"
  #include "tree-scalar-evolution.h"
  #include "params.h"
+ #include "tree-dfa.h"
  
  
  /* The maximum number of dominator BBs we search for conditions
*** expand_simple_operations (tree expr, tre
*** 1980,1985 
--- 1981,2001 
  
if (code == SSA_NAME)
return expand_simple_operations (e, stop);
+   else if (code == ADDR_EXPR)
+   {
+ HOST_WIDE_INT offset;
+ tree base = get_addr_base_and_unit_offset (TREE_OPERAND (e, 0),
+);
+ if (base
+ && TREE_CODE (base) == MEM_REF)
+   {
+ ee = expand_simple_operations (TREE_OPERAND (base, 0), stop);
+ return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (expr), ee,
+ wide_int_to_tree (sizetype,
+   mem_ref_offset (base)
+   + offset));
+   }
+   }
  
return expr;
  }
Index: gcc/testsuite/g++.dg/tree-ssa/pr81719.C
===
*** gcc/testsuite/g++.dg/tree-ssa/pr81719.C (nonexistent)
--- gcc/testsuite/g++.dg/tree-ssa/pr81719.C (working copy)
***
*** 0 
--- 1,24 
+ /* { dg-do compile { target c++11 } } */
+ /* { dg-options "-O3 -fdump-tree-optimized" } */
+ 
+ typedef int Items[2];
+ 
+ struct ItemArray
+ {
+   Items items;
+   int sum_x2() const;
+ };
+ 
+ int ItemArray::sum_x2() const
+ {
+   int total = 0;
+   for (int item : items)
+ {
+   total += item;
+ }
+   return total;
+ }
+ 
+ /* We should be able to compute the number of iterations to two, unroll
+the loop and end up with a single basic-block in sum_x2.  */
+ /* { dg-final { scan-tree-dump-times "bb" 1 "optimized" } } */