On Tue, 1 Jun 2021, Hongtao Liu via Gcc-patches wrote:
Hi:
This patch is about to simplify (view_convert:type ~a) < 0 to
(view_convert:type a) >= 0 when type is signed integer. Similar for
(view_convert:type ~a) >= 0.
Bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
Ok for the trunk?
gcc/ChangeLog:
PR middle-end/100738
* match.pd ((view_convert ~a) < 0 --> (view_convert a) >= 0,
(view_convert ~a) >= 0 --> (view_convert a) < 0): New GIMPLE
simplification.
We already have
/* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
(for cmp (simple_comparison)
scmp (swapped_simple_comparison)
(simplify
(cmp (bit_not@2 @0) CONSTANT_CLASS_P@1)
(if (single_use (@2)
&& (TREE_CODE (@1) == INTEGER_CST || TREE_CODE (@1) == VECTOR_CST))
(scmp @0 (bit_not @1)))))
Would it make sense to try and generalize it a bit, say with
(cmp (nop_convert1? (bit_not @0)) CONSTANT_CLASS_P)
(scmp (view_convert:XXX @0) (bit_not @1))
(I still believe that it is a bad idea that SSA_NAMEs are strongly typed,
encoding the type in operations would be more convenient, but I think the
time for that choice has long gone)
--
Marc Glisse
