[llvm-commits] [llvm] r41809 - /llvm/trunk/lib/CodeGen/README.txt

[Evan Cheng]

Author: evancheng
Date: Mon Sep 10 17:11:18 2007
New Revision: 41809

URL: http://llvm.org/viewvc/llvm-project?rev=41809&view=rev
Log:
Observation of rematerialization.

Modified:
    llvm/trunk/lib/CodeGen/README.txt

Modified: llvm/trunk/lib/CodeGen/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/README.txt?rev=41809&r1=41808&r2=41809&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/README.txt (original)
+++ llvm/trunk/lib/CodeGen/README.txt Mon Sep 10 17:11:18 2007
@@ -143,3 +143,8 @@
 ...
 load [T + 15]
 //===---------------------------------------------------------------------===//
+
+It's not always a good idea to choose rematerialization over spilling. If all
+the load / store instructions would be folded then spilling is cheaper because
+it won't require new live intervals / registers. See 2003-05-31-LongShifts for
+an example.