commit 36b6f7409d9f607317de9815ffc10656b608eab7
author David Majnemer <david.majnemer@gmail.com> Tue Jul 09 08:09:32 2013 +0000
committer David Majnemer <david.majnemer@gmail.com> Tue Jul 09 08:09:32 2013 +0000
tree 081e67d12a3ba9360c1ae1494a7e57cb912acb8e
parent ff16df71f50231c79c379a146dc55b4d6867cbd9

InstCombine: X & -C != -C -> X <= u ~C

Tests were added in r185910 somehow.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185912 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/InstCombine/InstCombineCompares.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index fd2b68a..e9f3458 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1277,6 +1277,15 @@
               return Res;
           }
     }
+
+    // X & -C == -C -> X >  u ~C
+    // X & -C != -C -> X <= u ~C
+    //   iff C is a power of 2
+    if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-RHSV).isPowerOf2())
+      return new ICmpInst(
+          ICI.getPredicate() == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_UGT
+                                                  : ICmpInst::ICMP_ULE,
+          LHSI->getOperand(0), SubOne(RHS));
     break;
 
   case Instruction::Or: {