From 95b9d6e5d8f35ccefccea0680ed733e752ff7d65 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Wed, 31 Jan 2007 19:49:20 +0000
Subject: A relatively simple PPC optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33709 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/PowerPC/README.txt | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'lib/Target/PowerPC/README.txt')

diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt
index 1c3e204d9d..2114fde89a 100644
--- a/lib/Target/PowerPC/README.txt
+++ b/lib/Target/PowerPC/README.txt
@@ -595,3 +595,30 @@ register of that class.  If it is then later necessary to spill that reg, so be
 it.
 
 ===-------------------------------------------------------------------------===
+
+We compile this:
+int test(_Bool X) {
+  return X ? 524288 : 0;
+}
+
+to: 
+_test:
+        cmplwi cr0, r3, 0
+        lis r2, 8
+        li r3, 0
+        beq cr0, LBB1_2 ;entry
+LBB1_1: ;entry
+        mr r3, r2
+LBB1_2: ;entry
+        blr 
+
+instead of:
+_test:
+        addic r2,r3,-1
+        subfe r0,r2,r3
+        slwi r3,r0,19
+        blr
+
+This sort of thing occurs a lot due to globalopt.
+
+===-------------------------------------------------------------------------===
-- 
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