dmp authored Oct 19, 2011 and dterei committed Nov 01, 2011

This patch changes the STG code so that %rsp to be aligned
to a 16-byte boundary + 8. This is the alignment required by
the x86_64 ABI on entry to a function. Previously we kept
%rsp aligned to a 16-byte boundary, but this was causing
problems for the LLVM backend (see #4211).

We now don't need to invoke llvm stack mangler on
x86_64 targets. Since the stack is now 16+8 byte algined in
STG land on x86_64, we don't need to mangle the stack
manipulations with the llvm mangler.

This patch only modifies the alignement for x86_64 backends.

Signed-off-by: David Terei <davidterei@gmail.com>