From: Chris Lattner <sabre@nondot.org>
Date: Sun, 19 Sep 2010 00:34:58 +0000 (+0000)
Subject: add a readme.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=702917d4e836ec8346c05aadbc2c1a461c6c3ca6;p=oota-llvm.git

add a readme.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114303 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt
index 3465779e344..4c80225d041 100644
--- a/lib/Target/PowerPC/README.txt
+++ b/lib/Target/PowerPC/README.txt
@@ -37,6 +37,31 @@ _f3:
 	ori r3, r2, 65535
 	blr 
 
+===-------------------------------------------------------------------------===
+
+This code:
+
+unsigned add32carry(unsigned sum, unsigned x) {
+ unsigned z = sum + x;
+ if (sum + x < x)
+     z++;
+ return z;
+}
+
+Should compile to something like:
+
+	addc r3,r3,r4
+	addze r3,r3
+
+instead we get:
+
+	add r3, r4, r3
+	cmplw cr7, r3, r4
+	mfcr r4 ; 1
+	rlwinm r4, r4, 29, 31, 31
+	add r3, r3, r4
+
+Ick.
 
 ===-------------------------------------------------------------------------===