AMDGPU: Fix cost model for 16-bit operations on gfx8

We should only divide the number of pieces to fit the packed instructions
if we actually have pk instructions. This increases the cost of copysign,
but is closer to the current codegen output. It could be much cheaper
than it is now.

Author: arsenm

llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp

@@ -721,7 +721,7 @@ GCNTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
   if (SLT == MVT::f64)
     return LT.first * NElts * get64BitInstrCost(CostKind);
 
-  if ((ST->has16BitInsts() && (SLT == MVT::f16 || SLT == MVT::i16)) ||
+  if ((ST->hasVOP3PInsts() && (SLT == MVT::f16 || SLT == MVT::i16)) ||
       (ST->hasPackedFP32Ops() && SLT == MVT::f32))
     NElts = (NElts + 1) / 2;
 

llvm/test/Analysis/CostModel/AMDGPU/canonicalize.ll

@@ -22,12 +22,12 @@ define void @canonicalize_f16() {
 ;
 ; GFX8-LABEL: 'canonicalize_f16'
 ; GFX8-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %f16 = call half @llvm.canonicalize.f16(half undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f16 = call <2 x half> @llvm.canonicalize.v2f16(<2 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3f16 = call <3 x half> @llvm.canonicalize.v3f16(<3 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v4f16 = call <4 x half> @llvm.canonicalize.v4f16(<4 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v5f16 = call <5 x half> @llvm.canonicalize.v5f16(<5 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v16f16 = call <16 x half> @llvm.canonicalize.v16f16(<16 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 48 for instruction: %v17f16 = call <17 x half> @llvm.canonicalize.v17f16(<17 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2f16 = call <2 x half> @llvm.canonicalize.v2f16(<2 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v3f16 = call <3 x half> @llvm.canonicalize.v3f16(<3 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v4f16 = call <4 x half> @llvm.canonicalize.v4f16(<4 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v5f16 = call <5 x half> @llvm.canonicalize.v5f16(<5 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v16f16 = call <16 x half> @llvm.canonicalize.v16f16(<16 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 96 for instruction: %v17f16 = call <17 x half> @llvm.canonicalize.v17f16(<17 x half> undef)
 ; GFX8-NEXT:  Cost Model: Found an estimated cost of 10 for instruction: ret void
 ;
 ; GFX9-LABEL: 'canonicalize_f16'
@@ -62,12 +62,12 @@ define void @canonicalize_f16() {
 ;
 ; GFX8-SIZE-LABEL: 'canonicalize_f16'
 ; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %f16 = call half @llvm.canonicalize.f16(half undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f16 = call <2 x half> @llvm.canonicalize.v2f16(<2 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3f16 = call <3 x half> @llvm.canonicalize.v3f16(<3 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v4f16 = call <4 x half> @llvm.canonicalize.v4f16(<4 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v5f16 = call <5 x half> @llvm.canonicalize.v5f16(<5 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v16f16 = call <16 x half> @llvm.canonicalize.v16f16(<16 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 48 for instruction: %v17f16 = call <17 x half> @llvm.canonicalize.v17f16(<17 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2f16 = call <2 x half> @llvm.canonicalize.v2f16(<2 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v3f16 = call <3 x half> @llvm.canonicalize.v3f16(<3 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v4f16 = call <4 x half> @llvm.canonicalize.v4f16(<4 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v5f16 = call <5 x half> @llvm.canonicalize.v5f16(<5 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v16f16 = call <16 x half> @llvm.canonicalize.v16f16(<16 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 96 for instruction: %v17f16 = call <17 x half> @llvm.canonicalize.v17f16(<17 x half> undef)
 ; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; GFX9-SIZE-LABEL: 'canonicalize_f16'

llvm/test/Analysis/CostModel/AMDGPU/copysign.ll

@@ -23,13 +23,13 @@ define void @copysign_f16() {
 ;
 ; GFX8-LABEL: 'copysign_f16'
 ; GFX8-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %f16 = call half @llvm.copysign.f16(half undef, half undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f16 = call <2 x half> @llvm.copysign.v2f16(<2 x half> undef, <2 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3f16 = call <3 x half> @llvm.copysign.v3f16(<3 x half> undef, <3 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v4f16 = call <4 x half> @llvm.copysign.v4f16(<4 x half> undef, <4 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v5f16 = call <5 x half> @llvm.copysign.v5f16(<5 x half> undef, <5 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v8f16 = call <8 x half> @llvm.copysign.v8f16(<8 x half> undef, <8 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v9f16 = call <9 x half> @llvm.copysign.v9f16(<9 x half> undef, <9 x half> undef)
-; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v16f16 = call <16 x half> @llvm.copysign.v16f16(<16 x half> undef, <16 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2f16 = call <2 x half> @llvm.copysign.v2f16(<2 x half> undef, <2 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v3f16 = call <3 x half> @llvm.copysign.v3f16(<3 x half> undef, <3 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v4f16 = call <4 x half> @llvm.copysign.v4f16(<4 x half> undef, <4 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v5f16 = call <5 x half> @llvm.copysign.v5f16(<5 x half> undef, <5 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v8f16 = call <8 x half> @llvm.copysign.v8f16(<8 x half> undef, <8 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v9f16 = call <9 x half> @llvm.copysign.v9f16(<9 x half> undef, <9 x half> undef)
+; GFX8-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v16f16 = call <16 x half> @llvm.copysign.v16f16(<16 x half> undef, <16 x half> undef)
 ; GFX8-NEXT:  Cost Model: Found an estimated cost of 10 for instruction: ret void
 ;
 ; GFX9-LABEL: 'copysign_f16'
@@ -67,13 +67,13 @@ define void @copysign_f16() {
 ;
 ; GFX8-SIZE-LABEL: 'copysign_f16'
 ; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %f16 = call half @llvm.copysign.f16(half undef, half undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f16 = call <2 x half> @llvm.copysign.v2f16(<2 x half> undef, <2 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3f16 = call <3 x half> @llvm.copysign.v3f16(<3 x half> undef, <3 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v4f16 = call <4 x half> @llvm.copysign.v4f16(<4 x half> undef, <4 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v5f16 = call <5 x half> @llvm.copysign.v5f16(<5 x half> undef, <5 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v8f16 = call <8 x half> @llvm.copysign.v8f16(<8 x half> undef, <8 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v9f16 = call <9 x half> @llvm.copysign.v9f16(<9 x half> undef, <9 x half> undef)
-; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v16f16 = call <16 x half> @llvm.copysign.v16f16(<16 x half> undef, <16 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2f16 = call <2 x half> @llvm.copysign.v2f16(<2 x half> undef, <2 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v3f16 = call <3 x half> @llvm.copysign.v3f16(<3 x half> undef, <3 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v4f16 = call <4 x half> @llvm.copysign.v4f16(<4 x half> undef, <4 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v5f16 = call <5 x half> @llvm.copysign.v5f16(<5 x half> undef, <5 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v8f16 = call <8 x half> @llvm.copysign.v8f16(<8 x half> undef, <8 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v9f16 = call <9 x half> @llvm.copysign.v9f16(<9 x half> undef, <9 x half> undef)
+; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v16f16 = call <16 x half> @llvm.copysign.v16f16(<16 x half> undef, <16 x half> undef)
 ; GFX8-SIZE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 ; GFX9-SIZE-LABEL: 'copysign_f16'

llvm/test/Transforms/SLPVectorizer/AMDGPU/slp-v2f16.ll

@@ -271,7 +271,9 @@ bb:
 }
 
 ; GCN-LABEL: @copysign_combine_v2f16
-; GCN: call <2 x half> @llvm.copysign.v2f16(
+; GFX8: call half @llvm.copysign.f16(
+; GFX8: call half @llvm.copysign.f16(
+; GFX9: call <2 x half> @llvm.copysign.v2f16(
 define void @copysign_combine_v2f16(ptr addrspace(1) %arg, half %sign) {
 bb:
   %tmp = tail call i32 @llvm.amdgcn.workitem.id.x()
@@ -290,8 +292,6 @@ bb:
 
 ; FIXME: Should always vectorize
 ; GCN-LABEL: @copysign_combine_v4f16
-; GCN: call <2 x half> @llvm.copysign.v2f16(
-
 ; GFX8: call half @llvm.copysign.f16(
 ; GFX8: call half @llvm.copysign.f16(
 
@@ -327,8 +327,10 @@ bb:
 }
 
 ; GCN-LABEL: @canonicalize_combine_v4f16
-; GCN: call <2 x half> @llvm.canonicalize.v2f16(
-; GCN: call <2 x half> @llvm.canonicalize.v2f16(
+; GFX8: call half @llvm.canonicalize.f16(
+; GFX8: call half @llvm.canonicalize.f16(
+
+; GFX9: call <2 x half> @llvm.canonicalize.v2f16(
 define void @canonicalize_combine_v4f16(ptr addrspace(1) %arg) {
 bb:
   %tmp = tail call i32 @llvm.amdgcn.workitem.id.x()