From c1853e4a0355a7a7d48bd314024967d462d983e1 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 6 Jan 2011 07:09:23 +0000
Subject: [PATCH] add a trivial instcombine missed in Dhrystone

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122953 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/README.txt | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index fa5e6010cfc..a02863c6a47 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -1964,4 +1964,41 @@ This occurs several times in viterbi.
 
 //===---------------------------------------------------------------------===//
 
+This code (from Benchmarks/Dhrystone/dry.c):
+
+define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
+entry:
+  %sext = shl i32 %0, 24
+  %conv = ashr i32 %sext, 24
+  %sext6 = shl i32 %1, 24
+  %conv4 = ashr i32 %sext6, 24
+  %cmp = icmp eq i32 %conv, %conv4
+  %. = select i1 %cmp, i32 10000, i32 0
+  ret i32 %.
+}
+
+Should be simplified into something like:
+
+define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
+entry:
+  %sext = shl i32 %0, 24
+  %conv = and i32 %sext, 0xFF000000
+  %sext6 = shl i32 %1, 24
+  %conv4 = and i32 %sext6, 0xFF000000
+  %cmp = icmp eq i32 %conv, %conv4
+  %. = select i1 %cmp, i32 10000, i32 0
+  ret i32 %.
+}
+
+and then to:
+
+define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
+entry:
+  %conv = and i32 %0, 0xFF
+  %conv4 = and i32 %1, 0xFF
+  %cmp = icmp eq i32 %conv, %conv4
+  %. = select i1 %cmp, i32 10000, i32 0
+  ret i32 %.
+}
+//===---------------------------------------------------------------------===//