[PATCH v2 0/2] aarch64: extend the number of supported feature bits

[Richard Earnshaw]

This is an alternative approach to the patch Ezra posted in
https://sourceware.org/pipermail/binutils/2025-May/141183.html but
attempts to address to make future changes more straight forward.  It
works by using some macro trickery to replicate the necessary
statements so that in future we only need to change the replication
macro itself plus the number of feature bits we want to support.

A static assert further validates at compile time that there is enough
space to accommodate all the required feature bits.  Note that we
no-longer need to add dummy padding features to keep the macros and C
code in sync.

The series is divided into two patches.  The first makes all the
necessary changes to the macros.  The second is the patch that extends
the number of feature bits.  This is what would also need to change in
future if/when we need to move to 4 feature words.

Changes since v1:

o  Eliminate the need for AARCH64_MAX_FEATURES by synthesizing it from the number
   of replications.
o  Improve the assertion by validating the replication count.
o  Use aarch64_feature_word as the type for the flags field instead of
   directly using uint64_t.

I'll hold off committing this change until next week, just to allow
some time for comments.

Richard Earnshaw (2):
  aarch64: use macro trickery to automate feature array size replication
  aarch64: Increase the number of feature words to 3

 include/opcode/aarch64.h | 118 +++++++++++++++++++++++++++------------
 1 file changed, 82 insertions(+), 36 deletions(-)

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2.43.0