> On 5 Dec 2024, at 16:56, Richard Sandiford <richard.sandif...@arm.com> wrote:
>
> External email: Use caution opening links or attachments
>
>
> Jennifer Schmitz <jschm...@nvidia.com> writes:
>> @@ -3622,6 +3631,57 @@ gimple_folder::redirect_pred_x ()
>> return redirect_call (instance);
>> }
>>
>> +/* Fold calls with predicate pfalse:
>> + _m predication: lhs = op1.
>> + _x or _z: lhs = {0, ...}.
>> + Implicit predication that reads from memory: lhs = {0, ...}.
>> + Implicit predication that writes to memory or prefetches: no-op.
>> + Return the new gimple statement on success, else NULL. */
>> +gimple *
>> +gimple_folder::fold_pfalse ()
>> +{
>> + if (pred == PRED_none)
>> + return nullptr;
>> + tree arg0 = gimple_call_arg (call, 0);
>> + if (pred == PRED_m)
>> + {
>> + /* Unary function shapes with _m predication are folded to the
>> + inactive vector (arg0), while other function shapes are folded
>> + to op1 (arg1). */
>> + tree arg1 = gimple_call_arg (call, 1);
>> + tree t;
>> + if (is_pfalse (arg1))
>> + t = arg0;
>> + else if (is_pfalse (arg0))
>> + t = arg1;
>> + else
>> + return nullptr;
>> + /* In some intrinsics, e.g. svqshlu, lhs and op1 have different types,
>> + such that folding to op1 needs a type conversion. */
>> + if (TREE_TYPE (t) == TREE_TYPE (lhs))
>> + return fold_call_to (t);
>> + else
>> + {
>> + tree rhs = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), t);
>> + return gimple_build_assign (lhs, VIEW_CONVERT_EXPR, rhs);
>> + }
>
> I think we should move the VIEW_CONVERT_EXPR into fold_call_to,
> in case it's useful elsewhere. Admittedly that could also mask bugs,
> but still, it's seems like a nice facility to have.
>
> Using types_compatible_p (TREE_TYPE (lhs), TREE_TYPE (t)) would be
> more general than direct == between types.
>
> This block would then become:
>
> /* Unary function shapes with _m predication are folded to the
> inactive vector (arg0), while other function shapes are folded
> to op1 (arg1). */
> tree arg1 = gimple_call_arg (call, 1);
> if (is_pfalse (arg1))
> return fold_call_to (arg0);
> if (is_pfalse (arg0))
> return fold_call_to (arg1);
> return nullptr;
>
>> + }
>> + if ((pred == PRED_x || pred == PRED_z) && is_pfalse (arg0))
>> + return fold_call_to (build_zero_cst (TREE_TYPE (lhs)));
>> + if (pred == PRED_implicit && is_pfalse (arg0))
>> + {
>> + unsigned int flags = call_properties ();
>> + /* Folding to lhs = {0, ...} is not appropriate for intrinsics with
>> + AGGREGATE types as lhs. */
>> + if ((flags & CP_READ_MEMORY)
>> + && !AGGREGATE_TYPE_P (TREE_TYPE (lhs)))
>> + return fold_call_to (build_zero_cst (TREE_TYPE (lhs)));
>> + if (flags & (CP_WRITE_MEMORY | CP_PREFETCH_MEMORY))
>> + return fold_to_stmt_vops (gimple_build_nop ());
>> + }
>> + return nullptr;
>> +}
>> +
>> /* Fold the call to constant VAL. */
>> gimple *
>> gimple_folder::fold_to_cstu (poly_uint64 val)
>> @@ -3724,6 +3784,23 @@ gimple_folder::fold_active_lanes_to (tree x)
>> return gimple_build_assign (lhs, VEC_COND_EXPR, pred, x, vec_inactive);
>> }
>>
>> +/* Fold call to assignment statement lhs = t. */
>> +gimple *
>> +gimple_folder::fold_call_to (tree t)
>> +{
>> + return fold_to_stmt_vops (gimple_build_assign (lhs, t));
>> +}
>
> This would then become something like:
>
> /* Fold the result of the call to T, bitcasting to the right type if
> necessary. */
> gimple *
> gimple_folder::fold_call_to (tree t)
> {
> if (types_compatible_p (TREE_TYPE (lhs), TREE_TYPE (t)))
> return fold_to_stmt_vops (gimple_build_assign (lhs, t));
>
> tree rhs = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), t);
> return fold_to_stmt_vops (gimple_build_assign (lhs, VIEW_CONVERT_EXPR, rhs));
> }
>
> OK with those changes, thanks.
Thank you. I made the changes and pushed to trunk:
5289540ed58e42ae66255e31f22afe4ca0a6e15e.
Best,
Jennifer
>
> Richard
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