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fold-const.c (tree_nonzero_bits): New function.

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* fold-const.c (tree_nonzero_bits): New function.
        * fold-const.h (tree_nonzero_bits): Likewise.
        * match.pd (POPCOUNT): New patterns to fold BUILTIN_POPCOUNT and
        friends.  POPCOUNT(x&1) => x&1, POPCOUNT(x)==0 => x==0, etc.

        * gcc.dg/fold-popcount-1.c: New testcase.
        * gcc.dg/fold-popcount-2.c: New testcase.
        * gcc.dg/fold-popcount-3.c: New testcase.
        * gcc.dg/fold-popcount-4.c: New testcase.

From-SVN: r260689
This commit is contained in:
Roger Sayle 2018-05-24 20:47:03 +00:00 committed by Jeff Law
parent 520fe2e324
commit ba6557e268
9 changed files with 233 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2018-05-24 Roger Sayle <roger@nextmovesoftware.com>
* fold-const.c (tree_nonzero_bits): New function.
* fold-const.h (tree_nonzero_bits): Likewise.
* match.pd (POPCOUNT): New patterns to fold BUILTIN_POPCOUNT and
friends. POPCOUNT(x&1) => x&1, POPCOUNT(x)==0 => x==0, etc.
2018-05-24 H.J. Lu <hongjiu.lu@intel.com>
PR target/85900

68
gcc/fold-const.c
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@ -14571,6 +14571,74 @@ c_getstr (tree src, unsigned HOST_WIDE_INT *strlen)
return string + offset;
}
/* Given a tree T, compute which bits in T may be nonzero. */
wide_int
tree_nonzero_bits (const_tree t)
{
switch (TREE_CODE (t))
{
case INTEGER_CST:
return wi::to_wide (t);
case SSA_NAME:
return get_nonzero_bits (t);
case NON_LVALUE_EXPR:
case SAVE_EXPR:
return tree_nonzero_bits (TREE_OPERAND (t, 0));
case BIT_AND_EXPR:
return wi::bit_and (tree_nonzero_bits (TREE_OPERAND (t, 0)),
tree_nonzero_bits (TREE_OPERAND (t, 1)));
case BIT_IOR_EXPR:
case BIT_XOR_EXPR:
return wi::bit_or (tree_nonzero_bits (TREE_OPERAND (t, 0)),
tree_nonzero_bits (TREE_OPERAND (t, 1)));
case COND_EXPR:
return wi::bit_or (tree_nonzero_bits (TREE_OPERAND (t, 1)),
tree_nonzero_bits (TREE_OPERAND (t, 2)));
CASE_CONVERT:
return wide_int::from (tree_nonzero_bits (TREE_OPERAND (t, 0)),
TYPE_PRECISION (TREE_TYPE (t)),
TYPE_SIGN (TREE_TYPE (TREE_OPERAND (t, 0))));
case PLUS_EXPR:
if (INTEGRAL_TYPE_P (TREE_TYPE (t)))
{
wide_int nzbits1 = tree_nonzero_bits (TREE_OPERAND (t, 0));
wide_int nzbits2 = tree_nonzero_bits (TREE_OPERAND (t, 1));
if (wi::bit_and (nzbits1, nzbits2) == 0)
return wi::bit_or (nzbits1, nzbits2);
}
break;
case LSHIFT_EXPR:
if (TREE_CODE (TREE_OPERAND (t, 1)) == INTEGER_CST)
{
tree type = TREE_TYPE (t);
wide_int nzbits = tree_nonzero_bits (TREE_OPERAND (t, 0));
wide_int arg1 = wi::to_wide (TREE_OPERAND (t, 1),
TYPE_PRECISION (type));
return wi::neg_p (arg1)
? wi::rshift (nzbits, -arg1, TYPE_SIGN (type))
: wi::lshift (nzbits, arg1);
}
break;
case RSHIFT_EXPR:
if (TREE_CODE (TREE_OPERAND (t, 1)) == INTEGER_CST)
{
tree type = TREE_TYPE (t);
wide_int nzbits = tree_nonzero_bits (TREE_OPERAND (t, 0));
wide_int arg1 = wi::to_wide (TREE_OPERAND (t, 1),
TYPE_PRECISION (type));
return wi::neg_p (arg1)
? wi::lshift (nzbits, -arg1)
: wi::rshift (nzbits, arg1, TYPE_SIGN (type));
}
break;
default:
break;
}
return wi::shwi (-1, TYPE_PRECISION (TREE_TYPE (t)));
}
#if CHECKING_P
namespace selftest {

1
gcc/fold-const.h
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@ -181,6 +181,7 @@ extern tree const_unop (enum tree_code, tree, tree);
extern tree const_binop (enum tree_code, tree, tree, tree);
extern bool negate_mathfn_p (combined_fn);
extern const char *c_getstr (tree, unsigned HOST_WIDE_INT *strlen = NULL);
extern wide_int tree_nonzero_bits (const_tree);
/* Return OFF converted to a pointer offset type suitable as offset for
POINTER_PLUS_EXPR. Use location LOC for this conversion. */

20
gcc/match.pd
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@ -4760,3 +4760,23 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(negate (IFN_FNMS@3 @0 @1 @2))
(if (single_use (@3))
(IFN_FMA @0 @1 @2))))
/* POPCOUNT simplifications. */
(for popcount (BUILT_IN_POPCOUNT BUILT_IN_POPCOUNTL BUILT_IN_POPCOUNTLL
BUILT_IN_POPCOUNTIMAX)
/* popcount(X&1) is nop_expr(X&1). */
(simplify
(popcount @0)
(if (tree_nonzero_bits (@0) == 1)
(convert @0)))
/* popcount(X) + popcount(Y) is popcount(X|Y) when X&Y must be zero. */
(simplify
(plus (popcount:s @0) (popcount:s @1))
(if (wi::bit_and (tree_nonzero_bits (@0), tree_nonzero_bits (@1)) == 0)
(popcount (bit_ior @0 @1))))
/* popcount(X) == 0 is X == 0, and related (in)equalities. */
(for cmp (le eq ne gt)
rep (eq eq ne ne)
(simplify
(cmp (popcount @0) integer_zerop)
(rep @0 { build_zero_cst (TREE_TYPE (@0)); }))))

7
gcc/testsuite/ChangeLog
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@ -1,3 +1,10 @@
2018-05-24 Roger Sayle <roger@nextmovesoftware.com>
* gcc.dg/fold-popcount-1.c: New testcase.
* gcc.dg/fold-popcount-2.c: New testcase.
* gcc.dg/fold-popcount-3.c: New testcase.
* gcc.dg/fold-popcount-4.c: New testcase.
2018-05-24 Marek Polacek <polacek@redhat.com>
PR c++/85847

35
gcc/testsuite/gcc.dg/fold-popcount-1.c Normal file
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@ -0,0 +1,35 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
int test_eqzero(unsigned int a)
{
return __builtin_popcount(a) == 0;
}
int test_eqzerol(unsigned long b)
{
return __builtin_popcountl(b) == 0;
}
int test_eqzeroll(unsigned long long c)
{
return __builtin_popcountll(c) == 0;
}
int test_nezero(unsigned int d)
{
return __builtin_popcount(d) != 0;
}
int test_nezerol(unsigned long e)
{
return __builtin_popcountl(e) != 0;
}
int test_nezeroll(unsigned long long f)
{
return __builtin_popcountll(f) != 0;
}
/* { dg-final { scan-tree-dump-times "popcount" 0 "original" } } */

35
gcc/testsuite/gcc.dg/fold-popcount-2.c Normal file
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@ -0,0 +1,35 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-cddce1" } */
int test_andone(unsigned int a)
{
return __builtin_popcount(a&1);
}
int test_andonel(unsigned long b)
{
return __builtin_popcountl(b&1);
}
int test_andonell(unsigned long long c)
{
return __builtin_popcountll(c&1);
}
int test_oneand(unsigned int d)
{
return __builtin_popcount(1&d);
}
int test_oneandl(unsigned long e)
{
return __builtin_popcountl(1&e);
}
int test_oneandll(unsigned long long f)
{
return __builtin_popcountll(1&f);
}
/* { dg-final { scan-tree-dump-times "popcount" 0 "cddce1" } } */

10
gcc/testsuite/gcc.dg/fold-popcount-3.c Normal file
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@ -0,0 +1,10 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-cddce1" } */
int test_combine(unsigned int a, unsigned int b)
{
return __builtin_popcount(a&8) + __builtin_popcount(b&2);
}
/* { dg-final { scan-tree-dump-times "popcount" 1 "cddce1" } } */

50
gcc/testsuite/gcc.dg/fold-popcount-4.c Normal file
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@ -0,0 +1,50 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-cddce1" } */
int test_shiftmax(unsigned int a)
{
return __builtin_popcount(a>>(8*sizeof(a)-1));
}
int test_shiftmaxl(unsigned long b)
{
return __builtin_popcountl(b>>(8*sizeof(b)-1));
}
int test_shiftmaxll(unsigned long long c)
{
return __builtin_popcountll(c>>(8*sizeof(c)-1));
}
int test_shift7(unsigned char d)
{
return __builtin_popcount(d>>7);
}
int test_shift7l(unsigned char e)
{
return __builtin_popcountl(e>>7);
}
int test_shift7ll(unsigned char f)
{
return __builtin_popcountll(f>>7);
}
int test_shift15(unsigned short g)
{
return __builtin_popcount(g>>15);
}
int test_shift15l(unsigned short h)
{
return __builtin_popcountl(h>>15);
}
int test_shift15ll(unsigned short i)
{
return __builtin_popcountll(i>>15);
}
/* { dg-final { scan-tree-dump-times "popcount" 0 "cddce1" } } */