Improve docs
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/alignment.h b/library/alignment.h
index db83595..fece47d 100644
--- a/library/alignment.h
+++ b/library/alignment.h
@@ -58,12 +58,15 @@
* gcc may generate a branch to memcpy for calls like `memcpy(dest, src, 4)` rather than
* generating some LDR or LDRB instructions (similar for stores).
*
- * For versions of gcc < 5.4.0 this always happens.
- * For gcc < 6.3.0, this happens at -O0
- * For all versions, this happens iff unaligned access is not supported.
+ * This is architecture dependent: x86-64 seems fine even with old gcc; 32-bit Arm
+ * is affected. To keep it simple, we enable for all architectures.
*
- * For gcc 4.x, this will generate byte-by-byte loads even if unaligned access is supported, which
- * is correct but not optimal.
+ * For versions of gcc < 5.4.0 this issue always happens.
+ * For gcc < 6.3.0, this issue happens at -O0
+ * For all versions, this issue happens iff unaligned access is not supported.
+ *
+ * For gcc 4.x, this implementation will generate byte-by-byte loads even if unaligned access is
+ * supported, which is correct but not optimal.
*
* For performance (and code size, in some cases), we want to avoid the branch and just generate
* some inline load/store instructions since the access is small and constant-size.
@@ -73,6 +76,9 @@
* possible alignment—one byte for a variable"
* https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc/Variable-Attributes.html
*
+ * Previous implementations used __attribute__((__aligned__(1)), but had issues with a gcc bug:
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94662
+ *
* Tested with several versions of GCC from 4.5.0 up to 13.2.0
* We don't enable for older than 4.5.0 as this has not been tested.
*/