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tree-optimization/94234 - add plusminus-with-convert pattern

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Add a rule (T)(A) +- (T)(B) -> (T)(A +- B), which works only when (A +- B)
could be folded to a simple value. By this rule, a plusminus-mult-with-convert
expression could be handed over to the rule (A * C) +- (B * C) -> (A +- B).

2020-09-15  Feng Xue  <fxue@os.amperecomputing.com>

gcc/
	PR tree-optimization/94234
	* match.pd (T)(A) +- (T)(B) -> (T)(A +- B): New simplification.

gcc/testsuite/
	PR tree-optimization/94234
	* gcc.dg/pr94234-3.c: New test.
This commit is contained in:
Feng Xue 2020-08-17 23:00:35 +08:00
parent 9e89fa0e2d
commit 8f0d743c2d
2 changed files with 57 additions and 0 deletions
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15
gcc/match.pd
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@ -2397,6 +2397,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(plus (convert @0) (op @2 (convert @1))))))
#endif
/* (T)(A) +- (T)(B) -> (T)(A +- B) only when (A +- B) could be simplified
to a simple value. */
#if GIMPLE
(for op (plus minus)
(simplify
(op (convert @0) (convert @1))
(if (INTEGRAL_TYPE_P (type)
&& INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@0))
&& types_match (TREE_TYPE (@0), TREE_TYPE (@1))
&& !TYPE_OVERFLOW_TRAPS (type)
&& !TYPE_OVERFLOW_SANITIZED (type))
(convert (op! @0 @1)))))
#endif
/* ~A + A -> -1 */
(simplify
(plus:c (bit_not @0) @0)

42
gcc/testsuite/gcc.dg/pr94234-3.c Normal file
View file

@ -0,0 +1,42 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-forwprop1" } */
typedef __SIZE_TYPE__ size_t;
typedef __PTRDIFF_TYPE__ ptrdiff_t;
ptrdiff_t foo1 (char *a, size_t n)
{
char *b1 = a + 8 * n;
char *b2 = a + 8 * (n - 1);
return b1 - b2;
}
int use_ptr (char *a, char *b);
ptrdiff_t foo2 (char *a, size_t n)
{
char *b1 = a + 8 * (n - 1);
char *b2 = a + 8 * n;
use_ptr (b1, b2);
return b1 - b2;
}
int use_int (int i);
unsigned goo (unsigned m_param, unsigned n_param)
{
unsigned b1 = m_param * (n_param + 2);
unsigned b2 = m_param * (n_param + 1);
int r = (int)(b1) - (int)(b2);
use_int (r);
return r;
}
/* { dg-final { scan-tree-dump-times "return 8;" 1 "forwprop1" } } */
/* { dg-final { scan-tree-dump-times "return -8;" 1 "forwprop1" } } */
/* { dg-final { scan-tree-dump-times "return m_param" 1 "forwprop1" } } */