From 966083fd1ad5adf801b767bba008ebaf0b9e06fa Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 17 Apr 2006 17:29:41 +0000 Subject: [PATCH] add a note git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27758 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/PowerPC/README_ALTIVEC.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/lib/Target/PowerPC/README_ALTIVEC.txt b/lib/Target/PowerPC/README_ALTIVEC.txt index 5d7ecd5691b..2887b798b0e 100644 --- a/lib/Target/PowerPC/README_ALTIVEC.txt +++ b/lib/Target/PowerPC/README_ALTIVEC.txt @@ -110,3 +110,13 @@ vec_ste(&destloc,0,vTemp); We can do an arbitrary non-constant value by using lvsr/perm/ste. //===----------------------------------------------------------------------===// + +If we want to tie instruction selection into the scheduler, we can do some +constant formation with different instructions. For example, we can generate +"vsplti -1" with "vcmpequw R,R" and 1,1,1,1 with "vsubcuw R,R", both of which +use different execution units, thus could help scheduling. + +This is probably only reasonable for a post-pass scheduler. + +//===----------------------------------------------------------------------===// +