From 3a7c33a853b03d9dcde400b9d58e02c25d9789db Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 19 Oct 2007 03:29:26 +0000
Subject: [PATCH] Add an easy microoptimization I noticed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43164 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/README.txt | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/Target/ARM/README.txt b/lib/Target/ARM/README.txt
index f05ae1c4230..1fb775064ef 100644
--- a/lib/Target/ARM/README.txt
+++ b/lib/Target/ARM/README.txt
@@ -573,3 +573,22 @@ __Z11no_overflowjj:
         bx lr
 
 //===---------------------------------------------------------------------===//
+
+Easy ARM microoptimization (with -mattr=+vfp2):
+
+define i64 @i(double %X) {
+        %Y = bitcast double %X to i64
+        ret i64 %Y
+}
+
+compiles into:
+
+_i:
+        fmdrr d0, r0, r1
+        fmrrd r0, r1, d0
+        bx lr
+
+This just needs a target-specific dag combine to merge the two ARMISD nodes.
+
+
+//===---------------------------------------------------------------------===//
-- 
2.34.1