tree 6e64598cff6886a795e906eba4c7503a4bf1cedb
parent b0921929650fb0a4a993a697baf8ad4f655748a3
author David Benjamin <davidben@google.com> 1582907920 -0500
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1582912579 +0000

Remove bn_sub_part_words assembly.

The assembly only existed for 32-bit x86, which is much less relevant
these days. It's also just a pile of ADDs, ADCs, etc., which compilers
should be able to figure out by now.

This frees us up to clean up that function, including the weird cl/dl
calling convention. No noticeable difference in RSA benchmarks:

Before:
Did 224 RSA 2048 signing operations in 1006100us (222.6 ops/sec)
Did 9240 RSA 2048 verify (same key) operations in 1078563us (8567.0 ops/sec)
Did 8541 RSA 2048 verify (fresh key) operations in 1064996us (8019.7 ops/sec)
Did 32 RSA 4096 signing operations in 1052851us (30.4 ops/sec)
Did 2365 RSA 4096 verify (same key) operations in 1093337us (2163.1 ops/sec)
Did 2222 RSA 4096 verify (fresh key) operations in 1090037us (2038.5 ops/sec)

After:
Did 231 RSA 2048 signing operations in 1018908us (226.7 ops/sec)
Did 9394 RSA 2048 verify (same key) operations in 1095548us (8574.7 ops/sec)
Did 8525 RSA 2048 verify (fresh key) operations in 1062449us (8023.9 ops/sec)
Did 32 RSA 4096 signing operations in 1050236us (30.5 ops/sec)
Did 2376 RSA 4096 verify (same key) operations in 1098509us (2162.9 ops/sec)
Did 2233 RSA 4096 verify (fresh key) operations in 1094724us (2039.8 ops/sec)

Bug: 314
Change-Id: I86a27b2550ab8bec2a9930cc509f4c29d6036b35
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/40144
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>