Re: [RFA] More type narrowing in match.pd V2

[Richard Biener <richard dot guenther at gmail dot com>]

On Sat, May 2, 2015 at 2:36 AM, Jeff Law <law@redhat.com> wrote:
> Here's an updated patch to add more type narrowing to match.pd.
>
> Changes since the last version:
>
> Slight refactoring of the condition by using types_match as suggested by
> Richi.  I also applied the new types_match to 2 other patterns in match.pd
> where it seemed clearly appropriate.
>
> Additionally the transformation is restricted by using the new single_use
> predicate.  I didn't change other patterns in match.pd to use the new
> single_use predicate.  But some probably could be changed.
>
> This (of course) continues to pass the bootstrap and regression check for
> x86-linux-gnu.
>
> There's still a ton of work to do in this space.  This is meant to be an
> incremental stand-alone improvement.
>
> OK now?

Ok with the {gimple,generic}-match-head.c changes mentioned in the ChangeLog.

Thanks,
Richard.

>
>
> Jeff
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index e006b26..5ee89de 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,8 @@
> +2015-05-01  Jeff Law  <law@redhat.com>
> +
> +       * match.pd (bit_and (plus/minus (convert @0) (convert @1) mask): New
> +       simplifier to narrow arithmetic.
> +
>  2015-05-01  Rasmus Villemoes  <rv@rasmusvillemoes.dk>
>
>         * match.pd: New simplification patterns.
> diff --git a/gcc/generic-match-head.c b/gcc/generic-match-head.c
> index daa56aa..303b237 100644
> --- a/gcc/generic-match-head.c
> +++ b/gcc/generic-match-head.c
> @@ -70,4 +70,20 @@ along with GCC; see the file COPYING3.  If not see
>  #include "dumpfile.h"
>  #include "generic-match.h"
>
> +/* Routine to determine if the types T1 and T2 are effectively
> +   the same for GENERIC.  */
>
> +inline bool
> +types_match (tree t1, tree t2)
> +{
> +  return TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2);
> +}
> +
> +/* Return if T has a single use.  For GENERIC, we assume this is
> +   always true.  */
> +
> +inline bool
> +single_use (tree t)
> +{
> +  return true;
> +}
> diff --git a/gcc/gimple-match-head.c b/gcc/gimple-match-head.c
> index c7b2f95..dc13218 100644
> --- a/gcc/gimple-match-head.c
> +++ b/gcc/gimple-match-head.c
> @@ -861,3 +861,21 @@ do_valueize (tree (*valueize)(tree), tree op)
>    return op;
>  }
>
> +/* Routine to determine if the types T1 and T2 are effectively
> +   the same for GIMPLE.  */
> +
> +inline bool
> +types_match (tree t1, tree t2)
> +{
> +  return types_compatible_p (t1, t2);
> +}
> +
> +/* Return if T has a single use.  For GIMPLE, we also allow any
> +   non-SSA_NAME (ie constants) and zero uses to cope with uses
> +   that aren't linked up yet.  */
> +
> +inline bool
> +single_use (tree t)
> +{
> +  return TREE_CODE (t) != SSA_NAME || has_zero_uses (t) || has_single_use
> (t);
> +}
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 87ecaf1..51a950a 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -289,8 +289,7 @@ along with GCC; see the file COPYING3.  If not see
>    (if (((TREE_CODE (@1) == INTEGER_CST
>          && INTEGRAL_TYPE_P (TREE_TYPE (@0))
>          && int_fits_type_p (@1, TREE_TYPE (@0)))
> -       || (GIMPLE && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1)))
> -       || (GENERIC && TREE_TYPE (@0) == TREE_TYPE (@1)))
> +       || types_match (TREE_TYPE (@0), TREE_TYPE (@1)))
>         /* ???  This transform conflicts with fold-const.c doing
>           Convert (T)(x & c) into (T)x & (T)c, if c is an integer
>           constants (if x has signed type, the sign bit cannot be set
> @@ -949,8 +948,7 @@ along with GCC; see the file COPYING3.  If not see
>  /* Unordered tests if either argument is a NaN.  */
>  (simplify
>   (bit_ior (unordered @0 @0) (unordered @1 @1))
> - (if ((GIMPLE && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1)))
> -      || (GENERIC && TREE_TYPE (@0) == TREE_TYPE (@1)))
> + (if (types_match (TREE_TYPE (@0), TREE_TYPE (@1)))
>    (unordered @0 @1)))
>  (simplify
>   (bit_ior:c (unordered @0 @0) (unordered:c@2 @0 @1))
> @@ -1054,7 +1052,7 @@ along with GCC; see the file COPYING3.  If not see
>     operation and convert the result to the desired type.  */
>  (for op (plus minus)
>    (simplify
> -    (convert (op (convert@2 @0) (convert@3 @1)))
> +    (convert (op@4 (convert@2 @0) (convert@3 @1)))
>      (if (INTEGRAL_TYPE_P (type)
>          /* We check for type compatibility between @0 and @1 below,
>             so there's no need to check that @1/@3 are integral types.  */
> @@ -1070,15 +1068,45 @@ along with GCC; see the file COPYING3.  If not see
>          && TYPE_PRECISION (type) == GET_MODE_PRECISION (TYPE_MODE (type))
>          /* The inner conversion must be a widening conversion.  */
>          && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE
> (@0))
> -        && ((GENERIC
> -             && (TYPE_MAIN_VARIANT (TREE_TYPE (@0))
> -                 == TYPE_MAIN_VARIANT (TREE_TYPE (@1)))
> -             && (TYPE_MAIN_VARIANT (TREE_TYPE (@0))
> -                 == TYPE_MAIN_VARIANT (type)))
> -            || (GIMPLE
> -                && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1))
> -                && types_compatible_p (TREE_TYPE (@0), type))))
> +        && types_match (TREE_TYPE (@0), TREE_TYPE (@1))
> +        && types_match (TREE_TYPE (@0), type)
> +        && single_use (@4))
>        (if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
>         (convert (op @0 @1)))
>        (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
>         (convert (op (convert:utype @0) (convert:utype @1)))))))
> +
> +/* This is another case of narrowing, specifically when there's an outer
> +   BIT_AND_EXPR which masks off bits outside the type of the innermost
> +   operands.   Like the previous case we have to convert the operands
> +   to unsigned types to avoid introducing undefined behaviour for the
> +   arithmetic operation.  */
> +(for op (minus plus)
> +  (simplify
> +    (bit_and (op@5 (convert@2 @0) (convert@3 @1)) INTEGER_CST@4)
> +    (if (INTEGRAL_TYPE_P (type)
> +        /* We check for type compatibility between @0 and @1 below,
> +           so there's no need to check that @1/@3 are integral types.  */
> +        && INTEGRAL_TYPE_P (TREE_TYPE (@0))
> +        && INTEGRAL_TYPE_P (TREE_TYPE (@2))
> +        /* The precision of the type of each operand must match the
> +           precision of the mode of each operand, similarly for the
> +           result.  */
> +        && (TYPE_PRECISION (TREE_TYPE (@0))
> +            == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (@0))))
> +        && (TYPE_PRECISION (TREE_TYPE (@1))
> +            == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (@1))))
> +        && TYPE_PRECISION (type) == GET_MODE_PRECISION (TYPE_MODE (type))
> +        /* The inner conversion must be a widening conversion.  */
> +        && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE
> (@0))
> +        && types_match (TREE_TYPE (@0), TREE_TYPE (@1))
> +        && (tree_int_cst_min_precision (@4, UNSIGNED)
> +            <= TYPE_PRECISION (TREE_TYPE (@0)))
> +        && single_use (@5))
> +      (if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
> +       (with { tree ntype = TREE_TYPE (@0); }
> +         (convert (bit_and (op @0 @1) (convert:ntype @4)))))
> +      (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
> +       (convert (bit_and (op (convert:utype @0) (convert:utype @1))
> +                         (convert:utype @4)))))))
> +
> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
> index 2aedc46..bd32179 100644
> --- a/gcc/testsuite/ChangeLog
> +++ b/gcc/testsuite/ChangeLog
> @@ -1,3 +1,7 @@
> +2015-05-01  Jeff Law  <law@redhat.com>
> +
> +       * gcc.dg/tree-ssa/shorten-1.c: New test.
> +
>  2015-05-01  Rasmus Villemoes  <rv@rasmusvillemoes.dk>
>
>         * gcc.dg/20150120-1.c: New test.
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/shorten-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/shorten-1.c
> new file mode 100644
> index 0000000..cecdd44
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/shorten-1.c
> @@ -0,0 +1,78 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +extern const unsigned char mode_ibit[];
> +extern const unsigned char mode_fbit[];
> +extern const signed char smode_ibit[];
> +extern const signed char smode_fbit[];
> +
> +/* We use bit-and rather than modulo to ensure we're actually
> +   testing the desired match.pd pattern.  */
> +unsigned char
> +muufubar (int indx)
> +{
> +  int ret = (mode_fbit [indx] - mode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +signed char
> +msufubar (int indx)
> +{
> +  int ret = (mode_fbit [indx] - mode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +unsigned char
> +musfubar (int indx)
> +{
> +  int ret = (smode_fbit [indx] - smode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +signed char
> +mssfubar (int indx)
> +{
> +  int ret = (smode_fbit [indx] - smode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +
> +unsigned char
> +puufubar (int indx)
> +{
> +  int ret = (mode_fbit [indx] + mode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +signed char
> +psufubar (int indx)
> +{
> +  int ret = (mode_fbit [indx] + mode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +unsigned char
> +pusfubar (int indx)
> +{
> +  int ret = (smode_fbit [indx] + smode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +signed char
> +pssfubar (int indx)
> +{
> +  int ret = (smode_fbit [indx] + smode_ibit [indx]) & 3;
> +  return ret;
> +}
> +
> +/* The shortening patterns in match.pd should arrange to do the
> +   arithmetic in char modes and thus any casts to ints should
> +   have been removed.  */
> +/* { dg-final {scan-tree-dump-not "\\(int\\)" "optimized"} } */
> +
> +/* We should have casted 4 operands from signed to unsigned char types.  */
> +/* { dg-final {scan-tree-dump-times "\\(unsigned char\\)" 8 "optimized" } }
> */
> +
> +/* And two return values should have been casted from unsigned char to
> +   a normal char.  */
> +/* { dg-final {scan-tree-dump-times "\\(signed char\\)" 4 "optimized" } }
> */
>