[PATCH] Use signed boolean type for boolean vectors
Mon Nov 9 14:27:00 GMT 2015
On Mon, Nov 9, 2015 at 3:03 PM, Ilya Enkovich <firstname.lastname@example.org> wrote:
> On 03 Nov 14:42, Richard Biener wrote:
>> On Wed, Oct 28, 2015 at 4:30 PM, Ilya Enkovich <email@example.com> wrote:
>> > 2015-10-28 18:21 GMT+03:00 Richard Biener <firstname.lastname@example.org>:
>> >> On Wed, Oct 28, 2015 at 2:13 PM, Ilya Enkovich <email@example.com> wrote:
>> >>> Hi,
>> >>> Testing boolean vector conversions I found several runtime regressions
>> >>> and investigation showed it's due to incorrect conversion caused by
>> >>> unsigned boolean type. When boolean vector is represented as an
>> >>> integer vector on target it's a signed integer actually. Unsigned
>> >>> boolean type was chosen due to possible single bit values, but for
>> >>> multiple bit values it causes wrong casting. The easiest way to fix
>> >>> it is to use signed boolean value. The following patch does this and
>> >>> fixes my problems with conversion. Bootstrapped and tested on
>> >>> x86_64-unknown-linux-gnu. Is it OK?
>> >> Hmm. Actually formally the "boolean" vectors were always 0 or -1
>> >> (all bits set). That is also true for a signed boolean with precision 1
>> >> but with higher precision what makes sure to sign-extend 'true'?
>> >> So it's far from an obvious change, esp as you don't change the
>> >> precision == 1 case. [I still think we should have precision == 1
>> >> for all boolean types]
>> >> Richard.
>> > For 1 bit precision signed type value 1 is out of range, right? This might break
>> > in many place due to used 1 as true value.
>> For vectors -1 is true. Did you try whether it breaks many places?
>> build_int_cst (type, 1) should still work fine.
> I tried it and didn't find any new failures. So looks I was wrong assuming it should cause many failures. Testing is not complete because many SPEC benchmarks are failing to compile on -O3 for AVX-512 on trunk. But I think we may proceed with signed type and fix constant generation issues if any revealed. This patch was bootstrapped and regtested on x86_64-unknown-linux-gnu. OK for trunk?
> 2015-11-09 Ilya Enkovich <firstname.lastname@example.org>
> * optabs.c (expand_vec_cond_expr): Always get sign from type.
> * tree.c (wide_int_to_tree): Support negative values for boolean.
> (build_nonstandard_boolean_type): Use signed type for booleans.
> diff --git a/gcc/optabs.c b/gcc/optabs.c
> index fdcdc6a..44971ad 100644
> --- a/gcc/optabs.c
> +++ b/gcc/optabs.c
> @@ -5365,7 +5365,6 @@ expand_vec_cond_expr (tree vec_cond_type, tree op0, tree op1, tree op2,
> op0a = TREE_OPERAND (op0, 0);
> op0b = TREE_OPERAND (op0, 1);
> tcode = TREE_CODE (op0);
> - unsignedp = TYPE_UNSIGNED (TREE_TYPE (op0a));
> @@ -5374,9 +5373,9 @@ expand_vec_cond_expr (tree vec_cond_type, tree op0, tree op1, tree op2,
> op0a = op0;
> op0b = build_zero_cst (TREE_TYPE (op0));
> tcode = LT_EXPR;
> - unsignedp = false;
> cmp_op_mode = TYPE_MODE (TREE_TYPE (op0a));
> + unsignedp = TYPE_UNSIGNED (TREE_TYPE (op0a));
> gcc_assert (GET_MODE_SIZE (mode) == GET_MODE_SIZE (cmp_op_mode)
> diff --git a/gcc/tree.c b/gcc/tree.c
> index 18d6544..6fb4c09 100644
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -1437,7 +1437,7 @@ wide_int_to_tree (tree type, const wide_int_ref &pcst)
> case BOOLEAN_TYPE:
> /* Cache false or true. */
> limit = 2;
> - if (hwi < 2)
> + if (IN_RANGE (hwi, 0, 1))
> ix = hwi;
> @@ -8069,7 +8069,7 @@ build_nonstandard_boolean_type (unsigned HOST_WIDE_INT precision)
> type = make_node (BOOLEAN_TYPE);
> TYPE_PRECISION (type) = precision;
> - fixup_unsigned_type (type);
> + fixup_signed_type (type);
> if (precision <= MAX_INT_CACHED_PREC)
> nonstandard_boolean_type_cache[precision] = type;
More information about the Gcc-patches