tree bc9a3aeb729fd7e14a7faf75cfda1740bf97006e
parent 76c6381c21ef07b13371120dc0b938da64f51ca7
author Brian Smith <brian@briansmith.org> 1455228616 -1000
committer David Benjamin <davidben@google.com> 1456416802 +0000

Simplify division-with-remainder calculations in crypto/bn/div.c.

Create a |bn_div_rem_words| that is used for double-word/single-word
divisions and division-with-remainder. Remove all implementations of
|bn_div_words| except for the implementation needed for 64-bit MSVC.
This allows more code to be shared across platforms and also removes
an instance of the dangerous pattern wherein the |div_asm| macro
modified a variable that wasn't passed as a parameter.

Also, document the limitations of the compiler-generated code for the
non-asm code paths more fully. Compilers indeed have not improved in
this respect.

Change-Id: I5a36a2edd7465de406d47d72dcd6bf3e63e5c232
Reviewed-on: https://boringssl-review.googlesource.com/7127
Reviewed-by: David Benjamin <davidben@google.com>