ARM cost model: Add costs for vector selects

Vector selects are cheap on NEON. They get lowered to a vbsl instruction.

radar://13158753

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174631 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 69 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMTargetTransformInfo.cpp b/lib/Target/ARM/ARMTargetTransformInfo.cpp
index bf83d51445..1f91e0ee36 100644
--- a/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ b/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -117,6 +117,8 @@ public:
   unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
                                       Type *Src) const;
 
+  unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy) const;
+
   unsigned getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) const;
   /// @}
 };
@@ -311,3 +313,16 @@ unsigned ARMTTI::getVectorInstrCost(unsigned Opcode, Type *ValTy,
 
   return TargetTransformInfo::getVectorInstrCost(Opcode, ValTy, Index);
 }
+
+unsigned ARMTTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
+                                    Type *CondTy) const {
+
+  int ISD = TLI->InstructionOpcodeToISD(Opcode);
+  // On NEON a a vector select gets lowered to vbsl.
+  if (ST->hasNEON() && ValTy->isVectorTy() && ISD == ISD::SELECT) {
+    std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(ValTy);
+    return LT.first;
+  }
+
+  return TargetTransformInfo::getCmpSelInstrCost(Opcode, ValTy, CondTy);
+}
diff --git a/test/Analysis/CostModel/ARM/select.ll b/test/Analysis/CostModel/ARM/select.ll
new file mode 100644
index 0000000000..96afccfc8c
--- /dev/null
+++ b/test/Analysis/CostModel/ARM/select.ll
@@ -0,0 +1,54 @@
+; RUN: opt < %s  -cost-model -analyze -mtriple=thumbv7-apple-ios6.0.0 -mcpu=swift | FileCheck %s
+target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
+target triple = "thumbv7-apple-ios6.0.0"
+
+; CHECK: casts
+define void @casts() {
+    ; Scalar values
+  ; CHECK: cost of 1 {{.*}} select
+  %v1 = select i1 undef, i8 undef, i8 undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v2 = select i1 undef, i16 undef, i16 undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v3 = select i1 undef, i32 undef, i32 undef
+  ; CHECK: cost of 2 {{.*}} select
+  %v4 = select i1 undef, i64 undef, i64 undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v5 = select i1 undef, float undef, float undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v6 = select i1 undef, double undef, double undef
+
+    ; Vector values
+  ; CHECK: cost of 1 {{.*}} select
+  %v7 = select <2 x i1> undef, <2 x i8> undef, <2 x i8> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v8 = select <4 x i1>  undef, <4 x i8> undef, <4 x i8> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v9 = select <8 x i1>  undef, <8 x i8> undef, <8 x i8> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v10 = select <16 x i1>  undef, <16 x i8> undef, <16 x i8> undef
+
+  ; CHECK: cost of 1 {{.*}} select
+  %v11 = select <2 x i1> undef, <2 x i16> undef, <2 x i16> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v12 = select <4 x i1>  undef, <4 x i16> undef, <4 x i16> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v13 = select <8 x i1>  undef, <8 x i16> undef, <8 x i16> undef
+
+  ; CHECK: cost of 1 {{.*}} select
+  %v14 = select <2 x i1> undef, <2 x i32> undef, <2 x i32> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v15 = select <4 x i1>  undef, <4 x i32> undef, <4 x i32> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v16 = select <2 x i1> undef, <2 x i64> undef, <2 x i64> undef
+
+  ; CHECK: cost of 1 {{.*}} select
+  %v17 = select <2 x i1> undef, <2 x float> undef, <2 x float> undef
+  ; CHECK: cost of 1 {{.*}} select
+  %v18 = select <4 x i1>  undef, <4 x float> undef, <4 x float> undef
+
+  ; CHECK: cost of 1 {{.*}} select
+  %v19 = select <2 x i1>  undef, <2 x double> undef, <2 x double> undef
+
+  ret void
+}