1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
index 48819335512..13d57c0934a 100644
--- a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -73,6 +73,17 @@ int ARMTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
       // Conversion to BIC is free, and means we can use ~Imm instead.
       return std::min(getIntImmCost(Imm, Ty), getIntImmCost(~Imm, Ty));
 
+  if (Opcode == Instruction::ICmp && Imm.isNegative() &&
+      Ty->getIntegerBitWidth() == 32) {
+    int64_t NegImm = -Imm.getSExtValue();
+    if (ST->isThumb2() && NegImm < 1<<12)
+      // icmp X, #-C -> cmn X, #C
+      return 0;
+    if (ST->isThumb() && NegImm < 1<<8)
+      // icmp X, #-C -> adds X, #C
+      return 0;
+  }
+
   return getIntImmCost(Imm, Ty);
 }