tree 19addb65efa4543549a8e3f810f641e647bd1512
parent 929f8428107c1b320566ae292c24c5340d5e37ed
author David Benjamin <davidben@google.com> 1510093450 -0500
committer Adam Langley <agl@google.com> 1510348023 +0000

Appease UBSan on pointer alignment.

Even without strict-aliasing, C does not allow casting pointers to types
that don't match their alignment. After this change, UBSan is happy with
our code at default settings but for the negative left shift language
bug.

Note: architectures without unaligned loads do not generate the same
code for memcpy and pointer casts. But even ARMv6 can perform unaligned
loads and stores (ARMv5 couldn't), so we should be okay here.

Before:
Did 11086000 AES-128-GCM (16 bytes) seal operations in 5000391us (2217026.6 ops/sec): 35.5 MB/s
Did 370000 AES-128-GCM (1350 bytes) seal operations in 5005208us (73923.0 ops/sec): 99.8 MB/s
Did 63000 AES-128-GCM (8192 bytes) seal operations in 5029958us (12525.0 ops/sec): 102.6 MB/s
Did 9894000 AES-256-GCM (16 bytes) seal operations in 5000017us (1978793.3 ops/sec): 31.7 MB/s
Did 316000 AES-256-GCM (1350 bytes) seal operations in 5005564us (63129.7 ops/sec): 85.2 MB/s
Did 54000 AES-256-GCM (8192 bytes) seal operations in 5054156us (10684.3 ops/sec): 87.5 MB/s

After:
Did 11026000 AES-128-GCM (16 bytes) seal operations in 5000197us (2205113.1 ops/sec): 35.3 MB/s
Did 370000 AES-128-GCM (1350 bytes) seal operations in 5005781us (73914.5 ops/sec): 99.8 MB/s
Did 63000 AES-128-GCM (8192 bytes) seal operations in 5032695us (12518.1 ops/sec): 102.5 MB/s
Did 9831750 AES-256-GCM (16 bytes) seal operations in 5000010us (1966346.1 ops/sec): 31.5 MB/s
Did 316000 AES-256-GCM (1350 bytes) seal operations in 5005702us (63128.0 ops/sec): 85.2 MB/s
Did 54000 AES-256-GCM (8192 bytes) seal operations in 5053642us (10685.4 ops/sec): 87.5 MB/s

(Tested with the no-asm builds; most of this code isn't reachable
otherwise.)

Change-Id: I025c365d26491abed0116b0de3b7612159e52297
Reviewed-on: https://boringssl-review.googlesource.com/22804
Reviewed-by: Adam Langley <agl@google.com>