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.
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?
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
