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| author | Jakub Jelinek <jakub@redhat.com> | 2021-05-12 09:46:03 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-05-12 09:46:03 +0200 |
| commit | f5f1838435400b837c8677c53a611e2dc6d56442 (patch) | |
| tree | 475063f4d70b5a5bc4ea6aa2f5431f6872c3e3ed /gcc/match.pd | |
| parent | e0c4c6bce88528773ee4445a540e86784fb72aa7 (diff) | |
| download | gcc-f5f1838435400b837c8677c53a611e2dc6d56442.zip gcc-f5f1838435400b837c8677c53a611e2dc6d56442.tar.gz gcc-f5f1838435400b837c8677c53a611e2dc6d56442.tar.bz2 | |
match.pd: Optimize (x & y) == x into (x & ~y) == 0 [PR94589]
> Somewhere in RTL (_M_value&1)==_M_value is turned into (_M_value&-2)==0,
> that could be worth doing already in GIMPLE.
Apparently it is
/* Simplify eq/ne (and/ior x y) x/y) for targets with a BICS instruction or
constant folding if x/y is a constant. */
if ((code == EQ || code == NE)
&& (op0code == AND || op0code == IOR)
&& !side_effects_p (op1)
&& op1 != CONST0_RTX (cmp_mode))
{
/* Both (eq/ne (and x y) x) and (eq/ne (ior x y) y) simplify to
(eq/ne (and (not y) x) 0). */
...
/* Both (eq/ne (and x y) y) and (eq/ne (ior x y) x) simplify to
(eq/ne (and (not x) y) 0). */
Yes, doing that on GIMPLE for the case where the not argument is constant
would simplify the phiopt follow-up (it would be single imm use then).
On Thu, May 06, 2021 at 09:42:41PM +0200, Marc Glisse wrote:
> We can probably do it in 2 steps, first something like
>
> (for cmp (eq ne)
> (simplify
> (cmp (bit_and:c @0 @1) @0)
> (cmp (@0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })))
>
> to get rid of the double use, and then simplify X&C==0 to X<=~C if C is a
> mask 111...000 (I thought we already had a function to detect such masks, or
> the 000...111, but I can't find them anymore).
Ok, here is the first step then.
2021-05-12 Jakub Jelinek <jakub@redhat.com>
Marc Glisse <marc.glisse@inria.fr>
PR tree-optimization/94589
* match.pd ((X & Y) == X -> (X & ~Y) == 0,
(X | Y) == Y -> (X & ~Y) == 0): New GIMPLE simplifications.
* gcc.dg/tree-ssa/pr94589-1.c: New test.
Diffstat (limited to 'gcc/match.pd')
| -rw-r--r-- | gcc/match.pd | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index 19f4a78..cdb8763 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -4764,6 +4764,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (cmp:c (bit_xor:c @0 @1) @0) (cmp @1 { build_zero_cst (TREE_TYPE (@1)); })) +#if GIMPLE + /* (X & Y) == X becomes (X & ~Y) == 0. */ + (simplify + (cmp:c (bit_and:c @0 @1) @0) + (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })) + + /* (X | Y) == Y becomes (X & ~Y) == 0. */ + (simplify + (cmp:c (bit_ior:c @0 @1) @1) + (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })) +#endif + /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */ (simplify (cmp (convert?@3 (bit_xor @0 INTEGER_CST@1)) INTEGER_CST@2) |