[Cost][X86] Add v2i64 truncation costs

We are missing costs for a lot of truncation cases, I'm hoping to address all the 'zero cost' cases in trunc.ll

I thought this was a vector widening side effect, but even before this we had some interesting LV decisions (notably over indvars) being made due to these zero costs.

llvm-svn: 372498

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index 7c5d54af34f..9b4a38630a4 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -1566,6 +1566,7 @@ int X86TTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
     { ISD::TRUNCATE,    MVT::v8i8,   MVT::v8i32,  3 },
     { ISD::TRUNCATE,    MVT::v8i16,  MVT::v8i32,  3 },
     { ISD::TRUNCATE,    MVT::v16i16, MVT::v16i32, 6 },
+    { ISD::TRUNCATE,    MVT::v2i8,   MVT::v2i64,  1 }, // PSHUFB
 
     { ISD::UINT_TO_FP,  MVT::f64,    MVT::i64,    4 },
   };
@@ -1637,6 +1638,9 @@ int X86TTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
     { ISD::TRUNCATE,    MVT::v16i8,  MVT::v16i32, 7 },
     { ISD::TRUNCATE,    MVT::v8i16,  MVT::v8i32,  5 },
     { ISD::TRUNCATE,    MVT::v16i16, MVT::v16i32, 10 },
+    { ISD::TRUNCATE,    MVT::v2i8,   MVT::v2i64,  4 }, // PAND+3*PACKUSWB
+    { ISD::TRUNCATE,    MVT::v2i16,  MVT::v2i64,  2 }, // PSHUFD+PSHUFLW
+    { ISD::TRUNCATE,    MVT::v2i32,  MVT::v2i64,  1 }, // PSHUFD
   };
 
   std::pair<int, MVT> LTSrc = TLI->getTypeLegalizationCost(DL, Src);