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match.pd: Simplify unsigned A - B - 1 >= A to B >= A [PR94913]

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Implemented thusly.  The TYPE_OVERFLOW_WRAPS is there just because the
pattern above it has it too, if you want, I can throw it away from both.

2020-05-08  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94913
	* match.pd (A - B + -1 >= A to B >= A): New simplification.
	(A - B > A to A < B): Don't test TYPE_OVERFLOW_WRAPS which is always
	true for TYPE_UNSIGNED integral types.

	* gcc.dg/tree-ssa/pr94913.c: New test.
This commit is contained in:
Jakub Jelinek 2020-05-08 09:32:20 +02:00
parent af1634f1b5
commit ff33680165
4 changed files with 52 additions and 2 deletions
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5
gcc/ChangeLog
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@ -1,5 +1,10 @@
2020-05-08 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/94913
* match.pd (A - B + -1 >= A to B >= A): New simplification.
(A - B > A to A < B): Don't test TYPE_OVERFLOW_WRAPS which is always
true for TYPE_UNSIGNED integral types.
PR bootstrap/94961
PR rtl-optimization/94516
* rtl.h (remove_reg_equal_equiv_notes): Add a bool argument defaulted

11
gcc/match.pd
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@ -4787,10 +4787,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(cmp:c (minus@2 @0 @1) @0)
(if (single_use (@2)
&& ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_UNSIGNED (TREE_TYPE (@0))
&& TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
&& TYPE_UNSIGNED (TREE_TYPE (@0)))
(cmp @1 @0))))
/* Optimize A - B + -1 >= A into B >= A for unsigned comparisons. */
(for cmp (ge lt)
(simplify
(cmp:c (plus (minus @0 @1) integer_minus_onep) @0)
(if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& TYPE_UNSIGNED (TREE_TYPE (@0)))
(cmp @1 @0))))
/* Testing for overflow is unnecessary if we already know the result. */
/* A - B > A */
(for cmp (gt le)

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2020-05-08 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/94913
* gcc.dg/tree-ssa/pr94913.c: New test.
2020-05-07 Segher Boessenkool <segher@kernel.crashing.org>
* gcc.target/powerpc/setnbc.h: New.

33
gcc/testsuite/gcc.dg/tree-ssa/pr94913.c Normal file
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@ -0,0 +1,33 @@
/* PR tree-optimization/94913 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
/* { dg-final { scan-tree-dump " (?:b_\[0-9]+\\\(D\\\) >= a|a_\[0-9]+\\\(D\\\) <= b)_\[0-9]+\\\(D\\\);" "optimized" } } */
/* { dg-final { scan-tree-dump " (?:c_\[0-9]+\\\(D\\\) > d|d_\[0-9]+\\\(D\\\) < c)_\[0-9]+\\\(D\\\);" "optimized" } } */
/* { dg-final { scan-tree-dump " (?:f_\[0-9]+\\\(D\\\) >= e|e_\[0-9]+\\\(D\\\) <= f)_\[0-9]+\\\(D\\\);" "optimized" } } */
/* { dg-final { scan-tree-dump " (?:g_\[0-9]+\\\(D\\\) > h|h_\[0-9]+\\\(D\\\) < g)_\[0-9]+\\\(D\\\);" "optimized" } } */
int
foo (unsigned a, unsigned b)
{
return (a - b - 1) >= a;
}
int
bar (unsigned c, unsigned d)
{
return (c - d - 1) < c;
}
int
baz (unsigned e, unsigned f)
{
unsigned t = e - f;
return (t - 1) >= e;
}
int
qux (unsigned g, unsigned h)
{
unsigned t = g - h;
return (t - 1) < g;
}