From: Nadav Rotem <nrotem@apple.com>
Date: Fri, 2 Nov 2012 21:47:47 +0000 (+0000)
Subject: Scalar Bitcasts and Truncs are usually free
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2b0c96f71ff1f26617dd805cafa35bf9a29c5a60;p=oota-llvm.git

Scalar Bitcasts and Truncs are usually free

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167323 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/TargetTransformImpl.cpp b/lib/Target/TargetTransformImpl.cpp
index dbbf37a7dd0..4cd07cd6c37 100644
--- a/lib/Target/TargetTransformImpl.cpp
+++ b/lib/Target/TargetTransformImpl.cpp
@@ -213,6 +213,11 @@ unsigned VectorTargetTransformImpl::getCastInstrCost(unsigned Opcode, Type *Dst,
 
   // Handle scalar conversions.
   if (!Src->isVectorTy() && !Dst->isVectorTy()) {
+
+    // Scalar bitcasts and truncs are usually free.
+    if (Opcode == Instruction::BitCast || Opcode == Instruction::Trunc)
+      return 0;
+
     // Just check the op cost. If the operation is legal then assume it costs 1.
     if (!TLI->isOperationExpand(ISD, DstLT.second))
       return  1;