In a later patch, I need to add "@" to a pattern that uses subst
iterators. This combination is problematic for two reasons:
(1) define_substs are applied and filtered at a later stage than the
handling of "@" patterns, so that the handling of "@" patterns
doesn't know which subst variants are valid and which will later be
dropped. Just adding a "@" therefore triggers a build error due to
references to non-existent patterns.
(2) Currently, the code will treat a single "@" pattern as contributing
to a single set of overloaded functions. These overloaded functions
will have an integer argument for every subst iterator. For example,
the vczle and vczbe in:
"@aarch64_rev<REVERSE:rev_op><mode><vczle><vczbe>"
are subst iterators, and so currently we'd try to generate a
single set of overloads that take four arguments: one for rev_op,
one for the mode, one for vczle, and one for vczbe. The gen_*
and maybe_gen_* functions will also have one rtx argument for
each operand in the original pattern.
This model doesn't really make sense for define_substs, since
define_substs are allowed to add extra operands to an instruction.
The number of rtx operands to the generators would then be
incorrect.
I think a more sensible way of handling define_substs would be to
apply them first (and thus expand things like <vczle> and <vczbe>
above) and then apply "@". However, that's a relatively invasive
change and not suitable for stage 3.
This patch instead skips over subst iterators and restricts "@"
overload handling to the cases where no define_subst is applied.
I looked through all uses of "@" names in target code and there
seemed to be only one current use of "@" with define_substs,
in x86 vector code. The current behaviour seemed to be unwanted there,
and the x86 code was having to work around it.
Tested on aarch64-linux-gnu and x86_64-linux-gnu. I think the x86
changes are bordering on obvious, but just in case: ok for those?
Thanks,
Richard
gcc/
* read-rtl.cc (md_reader::handle_overloaded_name): Don't add
arguments for uses of subst attributes.
(apply_iterators): Only add instructions to an overloaded helper
if they use the default subst iterator values.
* doc/md.texi: Update documentation accordingly.
* config/i386/i386-expand.cc (expand_vec_perm_broadcast_1): Update
accordingly.
---
gcc/config/i386/i386-expand.cc | 4 ++--
gcc/doc/md.texi | 5 +++++
gcc/read-rtl.cc | 18 ++++++++++++++----
3 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 6d25477841a..7f1dcd0937b 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -23884,7 +23884,7 @@ expand_vec_perm_broadcast_1 (struct expand_vec_perm_d
*d)
if (d->testing_p)
return true;
- rtx (*gen_interleave) (machine_mode, int, rtx, rtx, rtx);
+ rtx (*gen_interleave) (machine_mode, rtx, rtx, rtx);
if (elt >= nelt2)
{
gen_interleave = gen_vec_interleave_high;
@@ -23895,7 +23895,7 @@ expand_vec_perm_broadcast_1 (struct expand_vec_perm_d
*d)
nelt2 /= 2;
dest = gen_reg_rtx (vmode);
- emit_insn (gen_interleave (vmode, 1, dest, op0, op0));
+ emit_insn (gen_interleave (vmode, dest, op0, op0));
vmode = V4SImode;
op0 = gen_lowpart (vmode, dest);
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index f0b63a144ad..a997ab07f21 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -12359,4 +12359,9 @@ output and three inputs). This combination would
produce separate
each operand count, but it would still produce a single
@samp{maybe_code_for_@var{name}} and a single @samp{code_for_@var{name}}.
+Currently, these @code{@@} patterns only take into account patterns for
+which no @code{define_subst} has been applied (@pxref{Define Subst}).
+Any @samp{<@dots{}>} placeholders that refer to subst attributes
+(@pxref{Subst Iterators}) are ignored.
+
@end ifset
diff --git a/gcc/read-rtl.cc b/gcc/read-rtl.cc
index 195f78bd5e1..49a5306254b 100644
--- a/gcc/read-rtl.cc
+++ b/gcc/read-rtl.cc
@@ -814,9 +814,14 @@ md_reader::handle_overloaded_name (rtx original,
vec<mapping *> *iterators)
pending_underscore_p = false;
}
- /* Record an argument for ITERATOR. */
- iterators->safe_push (iterator);
- tmp_oname.arg_types.safe_push (iterator->group->type);
+ /* Skip define_subst iterators, since define_substs are allowed to
+ add new match_operands in their output templates. */
+ if (iterator->group != &substs)
+ {
+ /* Record an argument for ITERATOR. */
+ iterators->safe_push (iterator);
+ tmp_oname.arg_types.safe_push (iterator->group->type);
+ }
}
if (base == copy)
fatal_with_file_and_line ("no iterator attributes in name `%s'", name);
@@ -951,6 +956,7 @@ apply_iterators (rtx original, vec<rtx> *queue)
/* We apply subst iterator after RTL-template is copied, as during
subst-iterator processing, we could add an attribute to the
RTL-template, and we don't want to do it in the original one. */
+ bool add_oname = true;
FOR_EACH_VEC_ELT (iterator_uses, i, iuse)
{
v = iuse->iterator->current_value;
@@ -961,10 +967,14 @@ apply_iterators (rtx original, vec<rtx> *queue)
current_iterator_name = iuse->iterator->name;
iuse->iterator->group->apply_iterator (iuse->x, iuse->index,
v->number);
+ /* Only handle '@' overloading for the default value.
+ See handle_overloaded_name for details. */
+ if (v != iuse->iterator->values)
+ add_oname = false;
}
}
- if (oname)
+ if (oname && add_oname)
add_overload_instance (oname, iterators, x);
/* Add the new rtx to the end of the queue. */
--
2.25.1
