tree 28b91edf8b41ef7537d8c44afe5a438ed5f03492
parent 2608c6946f80e733875aa4969c39740fcb012c17
author sewardj <sewardj@8f6e269a-dfd6-0310-a8e1-e2731360e62c> 1425044036 +0000
committer sewardj <sewardj@8f6e269a-dfd6-0310-a8e1-e2731360e62c> 1425044036 +0000

Add machinery to try and transform A ^ ((A ^ B) & M)
into (A ^ ~M) | (B & M).

The former is MSVC's optimised idiom for bitfield assignment, the
latter is GCC's idiom.  The former causes Memcheck problems because it
doesn't understand that (in this complex case) XORing an undefined
value with itself produces a defined result.

Believed to be working but currently disabled.  To re-enable, change
if (0) to if (1) at line 6651.  Fixes, to some extent, and when
enabled, bug 344382.


git-svn-id: svn://svn.valgrind.org/vex/trunk@3097 8f6e269a-dfd6-0310-a8e1-e2731360e62c