[x86] fix cost of SINT_TO_FP for i32 --> float (PR21356, PR28434)

This is "cvtdq2ps" which does not appear to be particularly slow on any CPU
according to Agner's tables. Choosing "5" as a cost here as suggested in:
https://llvm.org/bugs/show_bug.cgi?id=21356
...but it seems very conservative given that the instruction is fully pipelined,
and I think these costs are supposed to model throughput.

Note that related costs are also most likely too high, but this fixes PR21356
and partly fixes PR28434.

llvm-svn: 274658

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index cd8bde93ae2..8fb72beb047 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -752,7 +752,7 @@ int X86TTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src) {
     { ISD::SINT_TO_FP, MVT::v2f64, MVT::v16i8, 16*10 },
     { ISD::SINT_TO_FP, MVT::v4f32, MVT::v8i16, 15 },
     { ISD::SINT_TO_FP, MVT::v2f64, MVT::v8i16, 8*10 },
-    { ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i32, 15 },
+    { ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i32, 5 },
     { ISD::SINT_TO_FP, MVT::v2f64, MVT::v4i32, 4*10 },
     { ISD::SINT_TO_FP, MVT::v4f32, MVT::v2i64, 15 },
     { ISD::SINT_TO_FP, MVT::v2f64, MVT::v2i64, 2*10 },