* OK, after changing to use liveIn/liveOut instead of IDEFs,
to avoid redundant mov out3=r44 type instructions, we need to
tell the register allocator the truth about out? registers.
FIXME: unfortunately, since the list of allocatable registers is immutable,
we can't simply 'delete r127' from the allocation order, say, if 'out0' is
used. The only correct thing we can do is have a linear order of regs:
out7, out6 ... out2, out1, out0, r32, r33, r34 ... r126, r127
and slide a 'window' of 96 registers along this line, depending on how many
of the out? regs a function actually uses. The only downside of this is
that the out? registers will be allocated _first_, which makes the
resulting assembly ugly. :( Note this in the README. Hope this gets fixed
soon. :) (note the 3rd person speech there)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21252 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/IA64/README b/lib/Target/IA64/README
index ec94299..d1a8fd2 100644
--- a/lib/Target/IA64/README
+++ b/lib/Target/IA64/README
@@ -55,6 +55,8 @@
TODO:
- clean up and thoroughly test the isel patterns.
+ - fix stacked register allocation order: (for readability) we don't want
+ the out? registers being the first ones used
- fix up floating point
(nb http://gcc.gnu.org/wiki?pagename=ia64%20floating%20point )
- bundling!