[llvm-commits] [llvm] r122953 - /llvm/trunk/lib/Target/README.txt

[Chris Lattner]

Author: lattner
Date: Thu Jan  6 01:09:23 2011
New Revision: 122953

URL: http://llvm.org/viewvc/llvm-project?rev=122953&view=rev
Log:
add a trivial instcombine missed in Dhrystone


Modified:
    llvm/trunk/lib/Target/README.txt

Modified: llvm/trunk/lib/Target/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/README.txt?rev=122953&r1=122952&r2=122953&view=diff
==============================================================================
--- llvm/trunk/lib/Target/README.txt (original)
+++ llvm/trunk/lib/Target/README.txt Thu Jan  6 01:09:23 2011
@@ -1964,4 +1964,41 @@
 
 //===---------------------------------------------------------------------===//
 
+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 %.
+}
+//===---------------------------------------------------------------------===//