2 files changed, 13 insertions, 12 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index a9aab86abd..4ecacf9d01 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -930,18 +930,6 @@ optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
 
 //===---------------------------------------------------------------------===//
 
-int g(int x) { return (x - 10) < 0; }
-Should combine to "x <= 9" (the sub has nsw).  Currently not
-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
-
-//===---------------------------------------------------------------------===//
-
-int g(int x) { return (x + 10) < 0; }
-Should combine to "x < -10" (the add has nsw).  Currently not
-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
-
-//===---------------------------------------------------------------------===//
-
 int f(int i, int j) { return i < j + 1; }
 int g(int i, int j) { return j > i - 1; }
 Should combine to "i <= j" (the add/sub has nsw).  Currently not
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 8c0ad52598..9bf3818954 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3008,6 +3008,19 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
     // icmp X, X+Cst
     if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
       return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate());
+
+    ConstantInt *Cst2;
+    if (match(Op1, m_ConstantInt(Cst)) &&
+        match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst2))) &&
+        cast<BinaryOperator>(Op0)->hasNoSignedWrap()) {
+      // icmp X+Cst2, Cst --> icmp X, Cst-Cst2
+      // iff Cst-Cst2 does not overflow
+      bool Overflow;
+      APInt NewCst = Cst->getValue().ssub_ov(Cst2->getValue(), Overflow);
+      if (!Overflow)
+        return new ICmpInst(I.getPredicate(), X,
+                            ConstantInt::get(Cst->getType(), NewCst));
+    }
   }
   return Changed ? &I : 0;
 }