Remove redundant AND from count reduction loop

[Marc Glisse]

On Tue, 23 Jun 2015, Richard Sandiford wrote:

> +/* Vector comparisons are defined to produce all-one or all-zero results.  */
> +(simplify
> + (vec_cond @0 integer_all_onesp@1 integer_zerop@2)
> + (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
> +   (convert @0)))

I am trying to understand why the test tree_nop_conversion_p is the right 
one (at least for the transformations not using VIEW_CONVERT_EXPR). By 
definition of VEC_COND_EXPR, type and TREE_TYPE (@0) are both integer 
vector types of the same size and number of elements. It thus seems like a 
conversion is always fine. For vectors, tree_nop_conversion_p apparently 
only checks that they have the same mode (quite often VOIDmode I guess).

> +/* We could instead convert all instances of the vec_cond to negate,
> +   but that isn't necessarily a win on its own.  */
> +(simplify
> + (plus:c @3 (vec_cond @0 integer_each_onep@1 integer_zerop@2))
> + (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
> +  (minus @3 (convert @0))))
> +
> +(simplify
> + (plus:c @3 (view_convert_expr

Aren't we suppose to drop _expr in match.pd?

> + 	     (vec_cond @0 integer_each_onep@1 integer_zerop@2)))
> + (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
> +  (minus @3 (convert @0))))
> +
> +(simplify
> + (minus @3 (vec_cond @0 integer_each_onep@1 integer_zerop@2))
> + (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
> +  (plus @3 (convert @0))))
> +
> +(simplify
> + (minus @3 (view_convert_expr
> + 	    (vec_cond @0 integer_each_onep@1 integer_zerop@2)))
> + (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
> +  (plus @3 (convert @0))))
> +
> /* Simplifications of comparisons.  */
>
> /* We can simplify a logical negation of a comparison to the
> Index: gcc/testsuite/gcc.target/aarch64/vect-add-sub-cond.c
> ===================================================================
> --- /dev/null	2015-06-02 17:27:28.541944012 +0100
> +++ gcc/testsuite/gcc.target/aarch64/vect-add-sub-cond.c	2015-06-23 12:06:27.120203685 +0100
> @@ -0,0 +1,94 @@
> +/* Make sure that vector comaprison results are not unnecessarily ANDed
> +   with vectors of 1.  */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -ftree-vectorize" } */
> +
> +#define COUNT1(X) if (X) count += 1
> +#define COUNT2(X) if (X) count -= 1
> +#define COUNT3(X) count += (X)
> +#define COUNT4(X) count -= (X)
> +
> +#define COND1(X) (X)
> +#define COND2(X) ((X) ? 1 : 0)
> +#define COND3(X) ((X) ? -1 : 0)
> +#define COND4(X) ((X) ? 0 : 1)
> +#define COND5(X) ((X) ? 0 : -1)
> +
> +#define TEST_LT(X, Y) ((X) < (Y))
> +#define TEST_LE(X, Y) ((X) <= (Y))
> +#define TEST_GT(X, Y) ((X) > (Y))
> +#define TEST_GE(X, Y) ((X) >= (Y))
> +#define TEST_EQ(X, Y) ((X) == (Y))
> +#define TEST_NE(X, Y) ((X) != (Y))
> +
> +#define COUNT_LOOP(ID, TYPE, CMP_ARRAY, TEST, COUNT) \
> +  TYPE \
> +  reduc_##ID (__typeof__ (CMP_ARRAY[0]) x) \
> +  { \
> +    TYPE count = 0; \
> +    for (unsigned int i = 0; i < 1024; ++i) \
> +      COUNT (TEST (CMP_ARRAY[i], x)); \
> +    return count; \
> +  }
> +
> +#define COND_LOOP(ID, ARRAY, CMP_ARRAY, TEST, COND) \
> +  void \
> +  plus_##ID (__typeof__ (CMP_ARRAY[0]) x) \
> +  { \
> +    for (unsigned int i = 0; i < 1024; ++i) \
> +      ARRAY[i] += COND (TEST (CMP_ARRAY[i], x)); \
> +  } \
> +  void \
> +  plusc_##ID (void) \
> +  { \
> +    for (unsigned int i = 0; i < 1024; ++i) \
> +      ARRAY[i] += COND (TEST (CMP_ARRAY[i], 10)); \
> +  } \
> +  void \
> +  minus_##ID (__typeof__ (CMP_ARRAY[0]) x) \
> +  { \
> +    for (unsigned int i = 0; i < 1024; ++i) \
> +      ARRAY[i] -= COND (TEST (CMP_ARRAY[i], x)); \
> +  } \
> +  void \
> +  minusc_##ID (void) \
> +  { \
> +    for (unsigned int i = 0; i < 1024; ++i) \
> +      ARRAY[i] += COND (TEST (CMP_ARRAY[i], 1)); \
> +  }
> +
> +#define ALL_LOOPS(ID, ARRAY, CMP_ARRAY, TEST) \
> +  typedef __typeof__(ARRAY[0]) ID##_type; \
> +  COUNT_LOOP (ID##_1, ID##_type, CMP_ARRAY, TEST, COUNT1) \
> +  COUNT_LOOP (ID##_2, ID##_type, CMP_ARRAY, TEST, COUNT2) \
> +  COUNT_LOOP (ID##_3, ID##_type, CMP_ARRAY, TEST, COUNT3) \
> +  COUNT_LOOP (ID##_4, ID##_type, CMP_ARRAY, TEST, COUNT4) \
> +  COND_LOOP (ID##_1, ARRAY, CMP_ARRAY, TEST, COND1) \
> +  COND_LOOP (ID##_2, ARRAY, CMP_ARRAY, TEST, COND2) \
> +  COND_LOOP (ID##_3, ARRAY, CMP_ARRAY, TEST, COND3) \
> +  COND_LOOP (ID##_4, ARRAY, CMP_ARRAY, TEST, COND4) \
> +  COND_LOOP (ID##_5, ARRAY, CMP_ARRAY, TEST, COND5)
> +
> +signed int asi[1024] __attribute__ ((aligned (16)));
> +unsigned int aui[1024] __attribute__ ((aligned (16)));
> +signed long long asl[1024] __attribute__ ((aligned (16)));
> +unsigned long long aul[1024] __attribute__ ((aligned (16)));
> +float af[1024] __attribute__ ((aligned (16)));
> +double ad[1024] __attribute__ ((aligned (16)));
> +
> +ALL_LOOPS (si_si, aui, asi, TEST_LT)
> +ALL_LOOPS (ui_si, aui, asi, TEST_LE)
> +ALL_LOOPS (si_ui, aui, asi, TEST_GT)
> +ALL_LOOPS (ui_ui, aui, asi, TEST_GE)
> +ALL_LOOPS (sl_sl, asl, asl, TEST_NE)
> +ALL_LOOPS (ul_ul, aul, aul, TEST_NE)
> +ALL_LOOPS (si_f, asi, af, TEST_LE)
> +ALL_LOOPS (ui_f, aui, af, TEST_GT)
> +ALL_LOOPS (sl_d, asl, ad, TEST_GE)
> +ALL_LOOPS (ul_d, aul, ad, TEST_GT)
> +
> +/* { dg-final { scan-assembler-not "\tand\t" } } */
> +/* { dg-final { scan-assembler-not "\tld\[^\t\]*\t\[wx\]" } } */
> +/* { dg-final { scan-assembler-not "\tst\[^\t\]*\t\[wx\]" } } */
> +/* { dg-final { scan-assembler "\tldr\tq" } } */
> +/* { dg-final { scan-assembler "\tstr\tq" } } */

-- 
Marc Glisse