Quoting "Paulo J. Matos" <pocma...@gmail.com>:
Hi,
For anyone who still remembers what went on with 3.3.3, in global.c,
set_preference, why is there a bias to set preference for operand 0 of
src?
I don't remember the detail of this specific code, but in general operand 0
is mostly used as an output operand; if an output operand can be assigned
a register, it is likely to be needed in a subsequent instruction to do
something with it.
- Does the order in which define_insn and define_expand rules show up
in the .md file bias the compiler to choose a rule in one way or the
other?
You may not have more than one pattern with the same name. define_insn
patterns will not be used for instruction pattern nor split point
recognition.
- If two define_insn patterns match the same insn, which one will be used?
The first one to be recognized. This is not necessarily the same as the first
one in the file, because insn code numbers are cached, and in general
not recomputed during or after reload. If the insn code caching has
an effect
on eventual instruction selection, it is usually a bug in the machine
description.
