From: Evan Cheng <evan.cheng@apple.com>
Date: Fri, 17 Feb 2006 00:04:28 +0000 (+0000)
Subject: Remind ourselves to revisit the "pxor vs. xorps/xorpd to clear XMM registers"
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7634ac4a9bf77b8188300ae3dffc4ce7f6703501;p=oota-llvm.git

Remind ourselves to revisit the "pxor vs. xorps/xorpd to clear XMM registers"
issue. Need to do more experiments.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26247 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index b794176fa53..5a2da2d3d26 100644
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -437,3 +437,9 @@ It might be better to generate
 	movw al, 8(%edx)
 	
 when we can spare a register. It reduces code size.
+
+//===---------------------------------------------------------------------===//
+
+It's not clear whether we should use pxor or xorps / xorpd to clear XMM
+registers. The choice may depend on subtarget information. We should do some
+more experiments on different x86 machines.