Peter Trommler authored Aug 31, 2016 and Ben Gamari committed Aug 31, 2016

According to the ABI specifications a minimal stack frame consists
of a header and a minimum size parameter save area. We reserve the
minimal size for each ABI.

On PowerPC 64-bil Linux and AIX the parameter save area can accomodate
up to eight parameters. So calls with eight parameters and fewer
can be done without allocating a new stack frame and deallocating
that stack frame after the call. On AIX one additional spill slot
is available on the stack.

Code size for all nofib benchmarks is 0.3 % smaller on powerpc64.

Test Plan: validate on AIX

Reviewers: hvr!, erikd, austin, simonmar, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2445