[google][4.6]Compiler Directed Multiversioning with new -mvarch option (issue 5490054)

[davidxl@google.com]

http://codereview.appspot.com/5490054/diff/1011/config/i386/i386.c
File config/i386/i386.c (right):

http://codereview.appspot.com/5490054/diff/1011/config/i386/i386.c#newcode26569
config/i386/i386.c:26569: +mversion_for_core2 (tree *optimization_node,
-> mversionable_for_core2_p ?

http://codereview.appspot.com/5490054/diff/1011/mversn-dispatch.c
File mversn-dispatch.c (right):

http://codereview.appspot.com/5490054/diff/1011/mversn-dispatch.c#newcode931
mversn-dispatch.c:931: DECL_STATIC_DESTRUCTOR (new_decl) = 0;
Should you assert it instead? Should not clone ctor/dtors.

http://codereview.appspot.com/5490054/diff/1011/mversn-dispatch.c#newcode2221
mversn-dispatch.c:2221: VEC_truncate (edge, EXIT_BLOCK_PTR->preds, 0);
{} --> remove

http://codereview.appspot.com/5490054/diff/1011/mversn-dispatch.c#newcode2389
mversn-dispatch.c:2389:
How does it interact with manual multi-versioning from user? You
probably don't want to clone functions that are marked with target
attributes (explicitly -- not implied from command line).

http://codereview.appspot.com/5490054/