From: Chris Lattner <sabre@nondot.org>
Date: Sat, 15 Jan 2011 05:41:33 +0000 (+0000)
Subject: Catch ~x < cst  just like ~x < ~y, we currently handle this through
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=fdb5b01df486f8fca44927a38dc9763e9d538e4c;p=oota-llvm.git

Catch ~x < cst  just like ~x < ~y, we currently handle this through
means that are about to disappear.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123515 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index bd339742ef2..220601611d7 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2284,11 +2284,15 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
     }
   }
   
-  // ~x < ~y --> y < x
   { Value *A, *B;
-    if (match(Op0, m_Not(m_Value(A))) &&
-        match(Op1, m_Not(m_Value(B))))
-      return new ICmpInst(I.getPredicate(), B, A);
+    // ~x < ~y --> y < x
+    // ~x < cst --> ~cst < x
+    if (match(Op0, m_Not(m_Value(A)))) {
+      if (match(Op1, m_Not(m_Value(B))))
+        return new ICmpInst(I.getPredicate(), B, A);
+      if (ConstantInt *RHSC = dyn_cast<ConstantInt>(B))
+        return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A);
+    }
 
     // (a+b) <u a  --> llvm.uadd.with.overflow.
     // (a+b) <u b  --> llvm.uadd.with.overflow.