[AARCH64][CostModel] Modified the cost of mask vector load/store

[david-arm]

I think the change seems sensible because the cost of a NEON load is probably similar to the cost of a SVE masked load on CPUs with SVE. However, I am curious to learn about the problem you're hitting. Are you looking at a specific benchmark or loop where the cost is too high to vectorise with SVE? Or is the cost preventing additional interleaving in the vectoriser?

[Miss_Grape]

In D134413#3808618, @david-arm wrote:

I think the change seems sensible because the cost of a NEON load is probably similar to the cost of a SVE masked load on CPUs with SVE. However, I am curious to learn about the problem you're hitting. Are you looking at a specific benchmark or loop where the cost is too high to vectorise with SVE? Or is the cost preventing additional interleaving in the vectoriser?

In the test case of sve-intrinsics-mask-ldst-ext.ll, I found that the instruction of llvm.masked.load.nxv/llvm.masked.store.nxv only corresponds to one assembly, so I think its correct cost should be 1

[david-arm]

In the test case of sve-intrinsics-mask-ldst-ext.ll, I found that the instruction of llvm.masked.load.nxv/llvm.masked.store.nxv only corresponds to one assembly, so I think its correct cost should be 1

OK thanks for the reply. The problem is that the cost isn't always due to the number of instructions, but also the cost in hardware of that instruction. In this particular case though, I think that the SVE ld1/st1 instructions are around the same cost as NEON loads/stores. Also, normal load/store IR nodes get lowered to a SVE ld1/st1, which have a cost of 1. I think this change fixes that inconsistency so I'm happy with it!

LGTM!

[thakis]

This broke check-llvm on all my bots:
http://45.33.8.238/linux/87588/step_12.txt
http://45.33.8.238/macm1/45335/step_11.txt
http://45.33.8.238/win/67006/step_11.txt

Also broke the official bots:
https://lab.llvm.org/buildbot/#/builders/109/builds/47509

Please take a look and revert for now if it takes a while to fix.

(And run tests before committing, and watch bots after.)

[fhahn]

In D134413#3820732, @thakis wrote:

This broke check-llvm on all my bots:
http://45.33.8.238/linux/87588/step_12.txt
http://45.33.8.238/macm1/45335/step_11.txt
http://45.33.8.238/win/67006/step_11.txt

Also broke the official bots:
https://lab.llvm.org/buildbot/#/builders/109/builds/47509

Please take a look and revert for now if it takes a while to fix.

(And run tests before committing, and watch bots after.)

I went ahead and reverted the commit in eba84971aeefd697f0c0afb96e1c2772745992d9 for now to get the bots back to green, as the test has been failing for a while.

[thakis]

Thanks!

[Miss_Grape]

Fixed failed test cases

[david-arm]

LGTM!

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

AArch64TTIImpl::getMaskedMemoryOpCost(unsigned Opcode, Type *Src,
 
   // The code-generator is currently not able to handle scalable vectors
   // of <vscale x 1 x eltty> yet, so return an invalid cost to avoid selecting
   // it. This change will be removed when code-generation for these types is
   // sufficiently reliable.
   if (cast<VectorType>(Src)->getElementCount() == ElementCount::getScalable(1))
     return InstructionCost::getInvalid();
 
-  return LT.first * 2;
+  return LT.first;
 }
 
 static unsigned getSVEGatherScatterOverhead(unsigned Opcode) {
   return Opcode == Instruction::Load ? SVEGatherOverhead : SVEScatterOverhead;
 }
 
 InstructionCost AArch64TTIImpl::getGatherScatterOpCost(
     unsigned Opcode, Type *DataTy, const Value *Ptr, bool VariableMask,

llvm/test/Analysis/CostModel/AArch64/masked_ldst.ll

entry:
   %v32f16 = call <32 x half> @llvm.masked.load.v32f16.p0v32f16(<32 x half> *undef, i32 8, <32 x i1> undef, <32 x half> undef)
 
   ret void
 }
 
 
 define void @scalable() {
 ; CHECK-LABEL: 'scalable'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2i8 = call <vscale x 2 x i8> @llvm.masked.load.nxv2i8.p0nxv2i8(<vscale x 2 x i8>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4i8 = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0nxv4i8(<vscale x 4 x i8>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0nxv8i8(<vscale x 8 x i8>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv16i8 = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0nxv16i8(<vscale x 16 x i8>* undef, i32 8, <vscale x 16 x i1> undef, <vscale x 16 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2i16 = call <vscale x 2 x i16> @llvm.masked.load.nxv2i16.p0nxv2i16(<vscale x 2 x i16>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4i16 = call <vscale x 4 x i16> @llvm.masked.load.nxv4i16.p0nxv4i16(<vscale x 4 x i16>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv8i16 = call <vscale x 8 x i16> @llvm.masked.load.nxv8i16.p0nxv8i16(<vscale x 8 x i16>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2i32 = call <vscale x 2 x i32> @llvm.masked.load.nxv2i32.p0nxv2i32(<vscale x 2 x i32>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i32> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4i32 = call <vscale x 4 x i32> @llvm.masked.load.nxv4i32.p0nxv4i32(<vscale x 4 x i32>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i32> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2i64 = call <vscale x 2 x i64> @llvm.masked.load.nxv2i64.p0nxv2i64(<vscale x 2 x i64>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i64> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2f16 = call <vscale x 2 x half> @llvm.masked.load.nxv2f16.p0nxv2f16(<vscale x 2 x half>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x half> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4f16 = call <vscale x 4 x half> @llvm.masked.load.nxv4f16.p0nxv4f16(<vscale x 4 x half>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x half> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv8f16 = call <vscale x 8 x half> @llvm.masked.load.nxv8f16.p0nxv8f16(<vscale x 8 x half>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x half> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2f32 = call <vscale x 2 x float> @llvm.masked.load.nxv2f32.p0nxv2f32(<vscale x 2 x float>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x float> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4f32 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0nxv4f32(<vscale x 4 x float>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x float> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv2f64 = call <vscale x 2 x double> @llvm.masked.load.nxv2f64.p0nxv2f64(<vscale x 2 x double>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x double> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2i8 = call <vscale x 2 x i8> @llvm.masked.load.nxv2i8.p0nxv2i8(<vscale x 2 x i8>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv4i8 = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0nxv4i8(<vscale x 4 x i8>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0nxv8i8(<vscale x 8 x i8>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv16i8 = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0nxv16i8(<vscale x 16 x i8>* undef, i32 8, <vscale x 16 x i1> undef, <vscale x 16 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2i16 = call <vscale x 2 x i16> @llvm.masked.load.nxv2i16.p0nxv2i16(<vscale x 2 x i16>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv4i16 = call <vscale x 4 x i16> @llvm.masked.load.nxv4i16.p0nxv4i16(<vscale x 4 x i16>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv8i16 = call <vscale x 8 x i16> @llvm.masked.load.nxv8i16.p0nxv8i16(<vscale x 8 x i16>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2i32 = call <vscale x 2 x i32> @llvm.masked.load.nxv2i32.p0nxv2i32(<vscale x 2 x i32>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv4i32 = call <vscale x 4 x i32> @llvm.masked.load.nxv4i32.p0nxv4i32(<vscale x 4 x i32>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2i64 = call <vscale x 2 x i64> @llvm.masked.load.nxv2i64.p0nxv2i64(<vscale x 2 x i64>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2f16 = call <vscale x 2 x half> @llvm.masked.load.nxv2f16.p0nxv2f16(<vscale x 2 x half>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x half> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv4f16 = call <vscale x 4 x half> @llvm.masked.load.nxv4f16.p0nxv4f16(<vscale x 4 x half>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x half> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv8f16 = call <vscale x 8 x half> @llvm.masked.load.nxv8f16.p0nxv8f16(<vscale x 8 x half>* undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x half> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2f32 = call <vscale x 2 x float> @llvm.masked.load.nxv2f32.p0nxv2f32(<vscale x 2 x float>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x float> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv4f32 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0nxv4f32(<vscale x 4 x float>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x float> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %nxv2f64 = call <vscale x 2 x double> @llvm.masked.load.nxv2f64.p0nxv2f64(<vscale x 2 x double>* undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x double> undef)
 ; CHECK-NEXT:  Cost Model: Invalid cost for instruction: %nxv1i64 = call <vscale x 1 x i64> @llvm.masked.load.nxv1i64.p0nxv1i64(<vscale x 1 x i64>* undef, i32 8, <vscale x 1 x i1> undef, <vscale x 1 x i64> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %nxv4i64 = call <vscale x 4 x i64> @llvm.masked.load.nxv4i64.p0nxv4i64(<vscale x 4 x i64>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i64> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %nxv32f16 = call <vscale x 32 x half> @llvm.masked.load.nxv32f16.p0nxv32f16(<vscale x 32 x half>* undef, i32 8, <vscale x 32 x i1> undef, <vscale x 32 x half> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %nxv4i64 = call <vscale x 4 x i64> @llvm.masked.load.nxv4i64.p0nxv4i64(<vscale x 4 x i64>* undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %nxv32f16 = call <vscale x 32 x half> @llvm.masked.load.nxv32f16.p0nxv32f16(<vscale x 32 x half>* undef, i32 8, <vscale x 32 x i1> undef, <vscale x 32 x half> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 ;
 entry:
   ; Legal scalable integer types
   %nxv2i8 = call <vscale x 2 x i8> @llvm.masked.load.nxv2i8.p0nxv2i8(<vscale x 2 x i8> *undef, i32 8, <vscale x 2 x i1> undef, <vscale x 2 x i8> undef)
   %nxv4i8 = call <vscale x 4 x i8> @llvm.masked.load.nxv4i8.p0nxv4i8(<vscale x 4 x i8> *undef, i32 8, <vscale x 4 x i1> undef, <vscale x 4 x i8> undef)
   %nxv8i8 = call <vscale x 8 x i8> @llvm.masked.load.nxv8i8.p0nxv8i8(<vscale x 8 x i8> *undef, i32 8, <vscale x 8 x i1> undef, <vscale x 8 x i8> undef)
   %nxv16i8 = call <vscale x 16 x i8> @llvm.masked.load.nxv16i8.p0nxv16i8(<vscale x 16 x i8> *undef, i32 8, <vscale x 16 x i1> undef, <vscale x 16 x i8> undef)

llvm/test/Analysis/CostModel/AArch64/masked_ldst_vls.ll

 ; RUN: opt < %s -passes="print<cost-model>" 2>&1 -disable-output -aarch64-sve-vector-bits-min=1920 | FileCheck %s -D#VBITS=1024
 ; RUN: opt < %s -passes="print<cost-model>" 2>&1 -disable-output -aarch64-sve-vector-bits-min=2048 | FileCheck %s -D#VBITS=2048
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64-unknown-linux-gnu"
 
 define void @fixed_sve_vls() #0 {
 ; CHECK-LABEL: 'fixed_sve_vls'
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(2047,VBITS)+1,2)]] for instruction: %v256i8 = call <256 x i8> @llvm.masked.load.v256i8.p0v256i8(<256 x i8>* undef, i32 8, <256 x i1> undef, <256 x i8> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(4091,VBITS)+1,2)]] for instruction: %v256i16 = call <256 x i16> @llvm.masked.load.v256i16.p0v256i16(<256 x i16>* undef, i32 8, <256 x i1> undef, <256 x i16> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(511,VBITS)+1,2)]] for instruction: %v16i32 = call <16 x i32> @llvm.masked.load.v16i32.p0v16i32(<16 x i32>* undef, i32 8, <16 x i1> undef, <16 x i32> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(1023,VBITS)+1,2)]] for instruction: %v16i64 = call <16 x i64> @llvm.masked.load.v16i64.p0v16i64(<16 x i64>* undef, i32 8, <16 x i1> undef, <16 x i64> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(8191,VBITS)+1,2)]] for instruction: %v512f16 = call <512 x half> @llvm.masked.load.v512f16.p0v512f16(<512 x half>* undef, i32 8, <512 x i1> undef, <512 x half> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(8191,VBITS)+1,2)]] for instruction: %v256f32 = call <256 x float> @llvm.masked.load.v256f32.p0v256f32(<256 x float>* undef, i32 8, <256 x i1> undef, <256 x float> undef)
-; CHECK:  Cost Model: Found an estimated cost of [[#mul(div(8191,VBITS)+1,2)]] for instruction: %v128f64 = call <128 x double> @llvm.masked.load.v128f64.p0v128f64(<128 x double>* undef, i32 8, <128 x i1> undef, <128 x double> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(2047,VBITS)+1]] for instruction: %v256i8 = call <256 x i8> @llvm.masked.load.v256i8.p0v256i8(<256 x i8>* undef, i32 8, <256 x i1> undef, <256 x i8> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(4091,VBITS)+1]] for instruction: %v256i16 = call <256 x i16> @llvm.masked.load.v256i16.p0v256i16(<256 x i16>* undef, i32 8, <256 x i1> undef, <256 x i16> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(511,VBITS)+1]] for instruction: %v16i32 = call <16 x i32> @llvm.masked.load.v16i32.p0v16i32(<16 x i32>* undef, i32 8, <16 x i1> undef, <16 x i32> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(1023,VBITS)+1]] for instruction: %v16i64 = call <16 x i64> @llvm.masked.load.v16i64.p0v16i64(<16 x i64>* undef, i32 8, <16 x i1> undef, <16 x i64> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(8191,VBITS)+1]] for instruction: %v512f16 = call <512 x half> @llvm.masked.load.v512f16.p0v512f16(<512 x half>* undef, i32 8, <512 x i1> undef, <512 x half> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(8191,VBITS)+1]] for instruction: %v256f32 = call <256 x float> @llvm.masked.load.v256f32.p0v256f32(<256 x float>* undef, i32 8, <256 x i1> undef, <256 x float> undef)
+; CHECK:  Cost Model: Found an estimated cost of [[#div(8191,VBITS)+1]] for instruction: %v128f64 = call <128 x double> @llvm.masked.load.v128f64.p0v128f64(<128 x double>* undef, i32 8, <128 x i1> undef, <128 x double> undef)
 ; CHECK:  Cost Model: Found an estimated cost of 0 for instruction: ret void
 entry:
   %v256i8 = call <256 x i8> @llvm.masked.load.v256i8.p0v256i8(<256 x i8> *undef, i32 8, <256 x i1> undef, <256 x i8> undef)
   %v256i16 = call <256 x i16> @llvm.masked.load.v256i16.p0v256i16(<256 x i16> *undef, i32 8, <256 x i1> undef, <256 x i16> undef)
   %v16i32 = call <16 x i32> @llvm.masked.load.v16i32.p0v16i32(<16 x i32> *undef, i32 8, <16 x i1> undef, <16 x i32> undef)
   %v16i64 = call <16 x i64> @llvm.masked.load.v16i64.p0v16i64(<16 x i64> *undef, i32 8, <16 x i1> undef, <16 x i64> undef)
 
   %v512f16 = call <512 x half> @llvm.masked.load.v512f16.p0v512f16(<512 x half> *undef, i32 8, <512 x i1> undef, <512 x half> undef)

llvm/test/Transforms/LoopVectorize/AArch64/masked-op-cost.ll

 for.inc:                                          ; preds = %for.body, %if.then
   %inc = add nuw nsw i64 %i.07, 1
   %exitcond.not = icmp eq i64 %inc, %n
   br i1 %exitcond.not, label %for.cond.cleanup.loopexit, label %for.body, !llvm.loop !5
 }
 
 
 ; CHECK-COST: Checking a loop in 'scalable'
-; CHECK-COST: Found an estimated cost of 2 for VF vscale x 4 For instruction:   store i32 2, i32* %arrayidx1, align 4
+; CHECK-COST: Found an estimated cost of 1 for VF vscale x 4 For instruction:   store i32 2, i32* %arrayidx1, align 4
 
 define void @scalable(i32* noalias nocapture %a, i32* noalias nocapture readonly %b, i64 %n) #0 {
 ; CHECK-LABEL: @scalable(
 ; CHECK: vector.body
 ; CHECK: call void @llvm.masked.store.nxv4i32.p0nxv4i32
 entry:
   %cmp6 = icmp sgt i64 %n, 0
   br i1 %cmp6, label %for.body.preheader, label %for.cond.cleanup