[llvm-commits] CVS: llvm/lib/Target/PowerPC/README_ALTIVEC.txt
Chris Lattner
lattner at cs.uiuc.edu
Mon Apr 17 10:30:04 PDT 2006
Changes in directory llvm/lib/Target/PowerPC:
README_ALTIVEC.txt updated: 1.25 -> 1.26
---
Log message:
add a note
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Diffs of the changes: (+10 -0)
README_ALTIVEC.txt | 10 ++++++++++
1 files changed, 10 insertions(+)
Index: llvm/lib/Target/PowerPC/README_ALTIVEC.txt
diff -u llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.25 llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.26
--- llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.25 Mon Apr 17 00:28:54 2006
+++ llvm/lib/Target/PowerPC/README_ALTIVEC.txt Mon Apr 17 12:29:41 2006
@@ -110,3 +110,13 @@
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.
+
+//===----------------------------------------------------------------------===//
+
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