On Fri, Jan 5, 2018 at 12:02 PM, Richard Sandiford
<richard.sandif...@linaro.org> wrote:
> Richard Biener <richard.guent...@gmail.com> writes:
>> On Mon, Nov 6, 2017 at 9:12 PM, Richard Sandiford
>> <richard.sandif...@linaro.org> wrote:
>>> initialize_matrix_A requires the CHREC_RIGHT to be an INTEGER_CST:
>>>
>>> switch (TREE_CODE (chrec))
>>> {
>>> case POLYNOMIAL_CHREC:
>>> A[index][0] = mult * int_cst_value (CHREC_RIGHT (chrec));
>>> return initialize_matrix_A (A, CHREC_LEFT (chrec), index + 1, mult);
>>>
>>> and isn't able to back out if it isn't. This patch instead
>>> checks for an appropriate CHREC_RIGHT before calling the parent
>>> function analyze_subscript_affine_affine.
>>>
>>> Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64-linux-gnu.
>>> OK to install?
>>
>> Hmm. I think this papers over some underlying issues. The calls are
>> guarded already with predicates that are supposed to veryify what you do.
>> Namely chrec_contains_symbols (a poly_int _does_ contain a "symbol").
>
> Yeah, I guess. "Symbol" seems to mean different things in different
> places: elsewhere it's !is_gimple_min_invariant, while in rtl it's
> specifically things that would have an assembler label. And "if it's
> not a symbol then it must be an INTEGER_CST" seems a bit dangerous in
> general, which I thought was why we also had
> evolution_function_right_is_integer_cst.
Yeah, well ... we do have quite some (too) many predicates here.
> E.g. tree-ssa-loop-ivcanon.c uses chrec_contains_symbols to test whether
> something is likely to be folded to a constant, and N * POLY_INT_CST
> would be folded to a POLY_INT_CST. So in that kind of usage we'd
> want chrec_contains_symbols to be false.
>
> But...
>
>> So can you please fix that by adding TREE_CODE (chrec) == POLY_INT
>> to the return true case?
>
> ...I don't have any proof that that causes problems in practice,
> so is the following OK?
Yes.
Thanks,
Richard.
> Thanks,
> Richard
>
>
> 2018-01-05 Richard Sandiford <richard.sandif...@linaro.org>
>
> gcc/
> * tree-chrec.c (chrec_contains_symbols): Return true for
> POLY_INT_CST.
>
> Index: gcc/tree-chrec.c
> ===================================================================
> --- gcc/tree-chrec.c 2018-01-03 11:12:56.820720031 +0000
> +++ gcc/tree-chrec.c 2018-01-05 11:01:00.520570935 +0000
> @@ -961,6 +961,7 @@ chrec_contains_symbols (const_tree chrec
>
> if (TREE_CODE (chrec) == SSA_NAME
> || VAR_P (chrec)
> + || TREE_CODE (chrec) == POLY_INT_CST
> || TREE_CODE (chrec) == PARM_DECL
> || TREE_CODE (chrec) == FUNCTION_DECL
> || TREE_CODE (chrec) == LABEL_DECL
