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[CostModel][AArch64] Remove amortization factor for some of the vector select instructions 

Summary:
We are not scalarizing the wide selects in codegen for i16 and i32 and
therefore we can remove the amortization factor. We still have issues
with i64 vectors in codegen though.

Reviewers: mcrosier

Subscribers: mcrosier, aemerson, llvm-commits, rengolin

Differential Revision: http://reviews.llvm.org/D12724

llvm-svn: 247156
This commit is contained in:
Silviu Baranga 2015-09-09 15:35:02 +00:00
parent 3f4228f613
commit a3e27edb5d
2 changed files with 11 additions and 10 deletions
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9
llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
View File

@ -380,15 +380,16 @@ int AArch64TTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
Type *CondTy) {
int ISD = TLI->InstructionOpcodeToISD(Opcode);
// We don't lower vector selects well that are wider than the register width.
// We don't lower some vector selects well that are wider than the register
// width.
if (ValTy->isVectorTy() && ISD == ISD::SELECT) {
// We would need this many instructions to hide the scalarization happening.
const int AmortizationCost = 20;
static const TypeConversionCostTblEntry<MVT::SimpleValueType>
VectorSelectTbl[] = {
{ ISD::SELECT, MVT::v16i1, MVT::v16i16, 16 * AmortizationCost },
{ ISD::SELECT, MVT::v8i1, MVT::v8i32, 8 * AmortizationCost },
{ ISD::SELECT, MVT::v16i1, MVT::v16i32, 16 * AmortizationCost },
{ ISD::SELECT, MVT::v16i1, MVT::v16i16, 16 },
{ ISD::SELECT, MVT::v8i1, MVT::v8i32, 8 },
{ ISD::SELECT, MVT::v16i1, MVT::v16i32, 16 },
{ ISD::SELECT, MVT::v4i1, MVT::v4i64, 4 * AmortizationCost },
{ ISD::SELECT, MVT::v8i1, MVT::v8i64, 8 * AmortizationCost },
{ ISD::SELECT, MVT::v16i1, MVT::v16i64, 16 * AmortizationCost }

12
llvm/test/Analysis/CostModel/AArch64/select.ll
View File

@ -17,16 +17,16 @@ define void @select() {
; CHECK: cost of 1 {{.*}} select
%v6 = select i1 undef, double undef, double undef
; Vector values - check for vectors that have a high cost because they end up
; scalarized.
; CHECK: cost of 320 {{.*}} select
; CHECK: cost of 16 {{.*}} select
%v13b = select <16 x i1> undef, <16 x i16> undef, <16 x i16> undef
; CHECK: cost of 160 {{.*}} select
; CHECK: cost of 8 {{.*}} select
%v15b = select <8 x i1> undef, <8 x i32> undef, <8 x i32> undef
; CHECK: cost of 320 {{.*}} select
; CHECK: cost of 16 {{.*}} select
%v15c = select <16 x i1> undef, <16 x i32> undef, <16 x i32> undef
; Vector values - check for vectors of i64s that have a high cost because
; they end up scalarized.
; CHECK: cost of 80 {{.*}} select
%v16a = select <4 x i1> undef, <4 x i64> undef, <4 x i64> undef
; CHECK: cost of 160 {{.*}} select
@ -34,5 +34,5 @@ define void @select() {
; CHECK: cost of 320 {{.*}} select
%v16c = select <16 x i1> undef, <16 x i64> undef, <16 x i64> undef
ret void
ret void
}