atch.pd: Ensure (op CONSTANT_CLASS_P CONSTANT_CLASS_P) is simplified [PR109505]
On the following testcase we hang, because POLY_INT_CST is CONSTANT_CLASS_P,
but BIT_AND_EXPR with it and INTEGER_CST doesn't simplify and the
(x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2)
simplification actually relies on the (CST1 & CST2) simplification,
otherwise it is a deoptimization, trading 2 ops for 3 and furthermore
running into
/* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
operands are another bit-wise operation with a common input. If so,
distribute the bit operations to save an operation and possibly two if
constants are involved. For example, convert
(A | B) & (A | C) into A | (B & C)
Further simplification will occur if B and C are constants. */
simplification which simplifies that
(x & CST2) | (CST1 & CST2) back to
CST2 & (x | CST1).
I went through all other places I could find where we have a simplification
with 2 CONSTANT_CLASS_P operands and perform some operation on those two,
while the other spots aren't that severe (just trade 2 operations for
another 2 if the two constants don't simplify, rather than as in the above
case trading 2 ops for 3), I still think all those spots really intend
to optimize only if the 2 constants simplify.
So, the following patch adds to those a ! modifier to ensure that,
even at GENERIC that modifier means !EXPR_P which is exactly what we want
IMHO.
2023-05-21 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/109505
* match.pd ((x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2),
Combine successive equal operations with constants,
(A +- CST1) +- CST2 -> A + CST3, (CST1 - A) +- CST2 -> CST3 - A,
CST1 - (CST2 - A) -> CST3 + A): Use ! on ops with 2 CONSTANT_CLASS_P
operands.
* gcc.target/aarch64/sve/pr109505.c: New test.