so it uses 5 funct3 values overall, which is appropriate, since swizzle is probably right after muladd in usage in graphics shaders.
-Alternative
+Alternative immed encoding
-
-+--------+----+-----------+----------+-------+-------+------+
++--------+-----------+----------+-------+-------+------+
| int/fp | 31:28 | 27:20 | 19:15 | 14:12 | 11:7 |
+========+===========+==========+=======+=======+======+
| int | DESTMASK | selector | rs | 000 | rd |
| fp | DESTMASK | constsel | rs | 011 | rd |
+--------+-----------+----------+-------+-------+------+
+Allows setting of arbitrary dest (xz, yw) without needing register-versions. Saves on instruction count.
+Needs 4 funct3 to express.
+
Matrix 4x4 Vector mul
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