Re: [PATCH][RFC] Do some vectorizer-friendly canonicalization before vectorization

[Dorit Nuzman <DORIT at il dot ibm dot com>]

Richard Guenther <rguenther@suse.de> wrote on 23/11/2006 12:39:40:

> The following passes for me on x86_64-unknown-linux-gnu.  Can you check
> it works on ppc?
>

sure:

the fast-math test passes, but the second test ICEs:

/home/dorit/mainline_dn/build/gcc/xgcc -B/home/dorit/mainline_dn/build/gcc/
/home/dorit/mainline_dn/gcc/gcc/testsuite/gcc.dg/vect/no-math-errno-vect-pow-2.c
   -O2 -ftree-vectorize -maltivec -fdump-tree-vect-details -fno-math-errno
-fno-show-column -S  -o no-math-errno-vect-pow-2.s
/home/dorit/mainline_dn/gcc/gcc/testsuite/gcc.dg/vect/no-math-errno-vect-pow-2.c:
 In function גfooג:
/home/dorit/mainline_dn/gcc/gcc/testsuite/gcc.dg/vect/no-math-errno-vect-pow-2.c:7:
 internal compiler error: Segmentation fault

gdb:
Program received signal SIGSEGV, Segmentation fault.
0x104f9460 in vect_pattern_recog (loop_vinfo=Variable "loop_vinfo" is not
available.
) at ../../gcc/gcc/tree-vect-patterns.c:631
631       if (VECTOR_MODE_P (TYPE_MODE (type_in)))
(gdb)

This is because 'base' (in vect_recog_pow_pattern) is actually of type
'double' (not 'float' as we would have expected), because there's a cast to
double - this is the dump before the vectorizer:

foo ()
{
  unsigned int ivtmp.34;
  int pretmp.27;
  int i;
  float D.1999;
  double D.1998;
  double D.1997;
  float D.1996;

<bb 2>:

  # ivtmp.34_1 = PHI <ivtmp.34_2(4), 256(2)>;
  # i_15 = PHI <i_12(4), 0(2)>;
<L0>:;
  D.1996_7 = x[i_15];
  D.1997_8 = (double) D.1996_7;
  D.1998_9 = __builtin_pow (D.1997_8, 5.0e-1);
  D.1999_10 = (float) D.1998_9;
  x[i_15] = D.1999_10;
  i_12 = i_15 + 1;
  ivtmp.34_2 = ivtmp.34_1 - 1;
  if (ivtmp.34_2 != 0) goto <L5>; else goto <L2>;

<L5>:;
  goto <bb 3> (<L0>);

<L2>:;
  return;


So this line probably fails to find a vectype:
*type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
and we don't check for that...

We need to check for target-support even if it's not a new tree-code, like
it's done in the other vect_recog_X_pattern functions.

Gotta run now,

dorit


> Thanks,
> Richard.
>
> 2006-11-23  Richard Guenther  <rguenther@suse.de>
>
>    * tree-vect-patterns.c (vect_recog_pow_pattern): Set
>    type_in to scalar type in recognition of squaring.
>
>    * gcc.dg/vect/vect.exp: Add support for -fno-math-errno tests.
>    * gcc.dg/vect/vect-pow-1.c: Rename ...
>    * gcc.dg/vect/fast-math-vect-pow-1.c: ... to this.  Use
>    floats instead of doubles, check successful vectorization.
>    * gcc.dg/vect/vect-pow-2.c: Rename ...
>    * gcc.dg/vect/no-math-errno-vect-pow-1.c: .. to this.  Use
>    floats instead of doubles.
>
> Index: tree-vect-patterns.c
> ===================================================================
> *** tree-vect-patterns.c   (revision 119115)
> --- tree-vect-patterns.c   (working copy)
> *************** vect_recog_pow_pattern (tree last_stmt,
> *** 466,472 ****
>     /* We now have a pow or powi builtin function call with a constant
>        exponent.  */
>
> -   *type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
>     *type_out = NULL_TREE;
>
>     /* Catch squaring.  */
> --- 466,471 ----
> *************** vect_recog_pow_pattern (tree last_stmt,
> *** 474,480 ****
>          && tree_low_cst (exp, 0) == 2)
>         || (TREE_CODE (exp) == REAL_CST
>             && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconst2)))
> !     return build2 (MULT_EXPR, TREE_TYPE (base), base, base);
>
>     /* Catch square root.  */
>     if (TREE_CODE (exp) == REAL_CST
> --- 473,482 ----
>          && tree_low_cst (exp, 0) == 2)
>         || (TREE_CODE (exp) == REAL_CST
>             && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconst2)))
> !     {
> !       *type_in = TREE_TYPE (base);
> !       return build2 (MULT_EXPR, TREE_TYPE (base), base, base);
> !     }
>
>     /* Catch square root.  */
>     if (TREE_CODE (exp) == REAL_CST
> *************** vect_recog_pow_pattern (tree last_stmt,
> *** 482,487 ****
> --- 484,490 ----
>       {
>         tree newfn = mathfn_built_in (TREE_TYPE (base), BUILT_IN_SQRT);
>         tree newarglist = build_tree_list (NULL_TREE, base);
> +       *type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
>         return build_function_call_expr (newfn, newarglist);
>       }

upto here it
>
> Index: testsuite/gcc.dg/vect/vect-pow-1.c
> ===================================================================
> *** testsuite/gcc.dg/vect/vect-pow-1.c   (revision 119115)
> --- testsuite/gcc.dg/vect/vect-pow-1.c   (working copy)
> ***************
> *** 1,14 ****
> - /* { dg-do compile } */
> - /* { dg-options "-O2 -ftree-vectorize -ffast-math -fdump-tree-
> vect-details" } */
> -
> - double x[256];
> -
> - void foo(void)
> - {
> -   int i;
> -   for (i=0; i<256; ++i)
> -     x[i] = x[i] * x[i];
> - }
> -
> - /* { dg-final { scan-tree-dump "pattern recognized" "vect" } } */
> - /* { dg-final { cleanup-tree-dump "vect" } } */
> --- 0 ----
> Index: testsuite/gcc.dg/vect/vect-pow-2.c
> ===================================================================
> *** testsuite/gcc.dg/vect/vect-pow-2.c   (revision 119115)
> --- testsuite/gcc.dg/vect/vect-pow-2.c   (working copy)
> ***************
> *** 1,14 ****
> - /* { dg-do compile } */
> - /* { dg-options "-O2 -ftree-vectorize -fno-math-errno -fdump-tree-
> vect-details" } */
> -
> - double x[256];
> -
> - void foo(void)
> - {
> -   int i;
> -   for (i=0; i<256; ++i)
> -     x[i] = __builtin_pow (x[i], 0.5);
> - }
> -
> - /* { dg-final { scan-tree-dump "pattern recognized" "vect" } } */
> - /* { dg-final { cleanup-tree-dump "vect" } } */
> --- 0 ----
> Index: testsuite/gcc.dg/vect/fast-math-vect-pow-1.c
> ===================================================================
> *** testsuite/gcc.dg/vect/fast-math-vect-pow-1.c   (revision 119115)
> --- testsuite/gcc.dg/vect/fast-math-vect-pow-1.c   (working copy)
> ***************
> *** 1,7 ****
>   /* { dg-do compile } */
> ! /* { dg-options "-O2 -ftree-vectorize -ffast-math -fdump-tree-
> vect-details" } */
>
> ! double x[256];
>
>   void foo(void)
>   {
> --- 1,7 ----
>   /* { dg-do compile } */
> ! /* { dg-require-effective-target vect_float } */
>
> ! float x[256];
>
>   void foo(void)
>   {
> *************** void foo(void)
> *** 10,14 ****
>       x[i] = x[i] * x[i];
>   }
>
> ! /* { dg-final { scan-tree-dump "pattern recognized" "vect" } } */
>   /* { dg-final { cleanup-tree-dump "vect" } } */
> --- 10,14 ----
>       x[i] = x[i] * x[i];
>   }
>
> ! /* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" } } */
>   /* { dg-final { cleanup-tree-dump "vect" } } */
> Index: testsuite/gcc.dg/vect/no-math-errno-vect-pow-1.c
> ===================================================================
> *** testsuite/gcc.dg/vect/no-math-errno-vect-pow-1.c   (revision 119115)
> --- testsuite/gcc.dg/vect/no-math-errno-vect-pow-1.c   (working copy)
> ***************
> *** 1,13 ****
>   /* { dg-do compile } */
> ! /* { dg-options "-O2 -ftree-vectorize -fno-math-errno -fdump-tree-
> vect-details" } */
>
> ! double x[256];
>
>   void foo(void)
>   {
>     int i;
>     for (i=0; i<256; ++i)
> !     x[i] = __builtin_pow (x[i], 0.5);
>   }
>
>   /* { dg-final { scan-tree-dump "pattern recognized" "vect" } } */
> --- 1,13 ----
>   /* { dg-do compile } */
> ! /* { dg-require-effective-target vect_float } */
>
> ! float x[256];
>
>   void foo(void)
>   {
>     int i;
>     for (i=0; i<256; ++i)
> !     x[i] = __builtin_powf (x[i], 0.5);
>   }
>
>   /* { dg-final { scan-tree-dump "pattern recognized" "vect" } } */
> Index: testsuite/gcc.dg/vect/vect.exp
> ===================================================================
> *** testsuite/gcc.dg/vect/vect.exp   (revision 119115)
> --- testsuite/gcc.dg/vect/vect.exp   (working copy)
> *************** lappend DEFAULT_VECTCFLAGS "-ffast-math"
> *** 97,102 ****
> --- 97,108 ----
>   dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/fast-math-
> vect*.\[cS\]]]  \
>      "" $DEFAULT_VECTCFLAGS
>
> + # -fno-math-errno tests
> + set DEFAULT_VECTCFLAGS $SAVED_DEFAULT_VECTCFLAGS
> + lappend DEFAULT_VECTCFLAGS "-fno-math-errno"
> + dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/no-math-errno-
> vect*.\[cS\]]]  \
> +    "" $DEFAULT_VECTCFLAGS
> +
>   # -fwrapv tests
>   set DEFAULT_VECTCFLAGS $SAVED_DEFAULT_VECTCFLAGS
>   lappend DEFAULT_VECTCFLAGS "-fwrapv"