Summary:
Some CPUID leafs depend on the value of ECX as well as EAX, but we left
it uninitialized.
Originally reported as https://crbug.com/901547
Reviewers: craig.topper, hans
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D54171
llvm-svn: 346265
Reid Kleckner