[AMDGPU] Vectorize i8 Shuffles #105850
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[AMDGPU] Vectorize i8 Shuffles #105850
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Change-Id: Ia995bc646e5f050083bd6277eeabe0b5ab410f47
Change-Id: I6e02e47b1e29458bf99d623488b29fd13ddb1b0b
Change-Id: Ifc338ac65db118812affc782e08d32ca6a27516e
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-llvm-analysis Author: Jeffrey Byrnes (jrbyrnes) Changesi8 shuffle vectors have standard isel dags and will be lowered into v_perms with CalculateByteProvider. Moreever, if we are unconvinced by #95328 , enabling i8 shuffle vectorization should indirectly capture many of the needed vectorization cases for #66838 . In that sense, this PR sort of competes with #95328 , though it does have standalone merits. This PR is meant for commits starting at b503e21 . Depends on #91016 Reopen of #95840 Patch is 130.67 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/105850.diff 8 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
index c38c2dc0f5f618..e09e09cf179e70 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
@@ -306,6 +306,23 @@ bool GCNTTIImpl::hasBranchDivergence(const Function *F) const {
return !F || !ST->isSingleLaneExecution(*F);
}
+unsigned GCNTTIImpl::getNumberOfParts(Type *Tp) {
+ // For certain 8 bit ops, we can pack a v4i8 into a single part
+ // (e.g. v4i8 shufflevectors -> v_perm v4i8, v4i8). Thus, we
+ // do not limit the numberOfParts for 8 bit vectors to the
+ // legalization costs of such. It is left up to other target
+ // queries (e.g. get*InstrCost) to decide the proper handling
+ // of 8 bit vectors.
+ if (FixedVectorType *VTy = dyn_cast<FixedVectorType>(Tp)) {
+ if (DL.getTypeSizeInBits(VTy->getElementType()) == 8) {
+ unsigned ElCount = VTy->getElementCount().getFixedValue();
+ return ElCount / 4;
+ }
+ }
+
+ return BaseT::getNumberOfParts(Tp);
+}
+
unsigned GCNTTIImpl::getNumberOfRegisters(unsigned RCID) const {
// NB: RCID is not an RCID. In fact it is 0 or 1 for scalar or vector
// registers. See getRegisterClassForType for the implementation.
@@ -337,9 +354,11 @@ unsigned GCNTTIImpl::getMinVectorRegisterBitWidth() const {
unsigned GCNTTIImpl::getMaximumVF(unsigned ElemWidth, unsigned Opcode) const {
if (Opcode == Instruction::Load || Opcode == Instruction::Store)
return 32 * 4 / ElemWidth;
- return (ElemWidth == 16 && ST->has16BitInsts()) ? 2
- : (ElemWidth == 32 && ST->hasPackedFP32Ops()) ? 2
- : 1;
+
+ return (ElemWidth == 8) ? 4
+ : (ElemWidth == 16) ? 2
+ : (ElemWidth == 32 && ST->hasPackedFP32Ops()) ? 2
+ : 1;
}
unsigned GCNTTIImpl::getLoadVectorFactor(unsigned VF, unsigned LoadSize,
@@ -1140,14 +1159,15 @@ InstructionCost GCNTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
Kind = improveShuffleKindFromMask(Kind, Mask, VT, Index, SubTp);
- // Larger vector widths may require additional instructions, but are
- // typically cheaper than scalarized versions.
- unsigned NumVectorElts = cast<FixedVectorType>(VT)->getNumElements();
+ unsigned ScalarSize = DL.getTypeSizeInBits(VT->getElementType());
if (ST->getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS &&
- DL.getTypeSizeInBits(VT->getElementType()) == 16) {
- bool HasVOP3P = ST->hasVOP3PInsts();
+ (ScalarSize == 16 || ScalarSize == 8)) {
+ // Larger vector widths may require additional instructions, but are
+ // typically cheaper than scalarized versions.
+ unsigned NumVectorElts = cast<FixedVectorType>(VT)->getNumElements();
unsigned RequestedElts =
count_if(Mask, [](int MaskElt) { return MaskElt != -1; });
+ unsigned EltsPerReg = 32 / ScalarSize;
if (RequestedElts == 0)
return 0;
switch (Kind) {
@@ -1156,9 +1176,9 @@ InstructionCost GCNTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
case TTI::SK_PermuteSingleSrc: {
// With op_sel VOP3P instructions freely can access the low half or high
// half of a register, so any swizzle of two elements is free.
- if (HasVOP3P && NumVectorElts == 2)
+ if (ST->hasVOP3PInsts() && ScalarSize == 16 && NumVectorElts == 2)
return 0;
- unsigned NumPerms = alignTo(RequestedElts, 2) / 2;
+ unsigned NumPerms = alignTo(RequestedElts, EltsPerReg) / EltsPerReg;
// SK_Broadcast just reuses the same mask
unsigned NumPermMasks = Kind == TTI::SK_Broadcast ? 1 : NumPerms;
return NumPerms + NumPermMasks;
@@ -1170,12 +1190,12 @@ InstructionCost GCNTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
return 0;
// Insert/extract subvectors only require shifts / extract code to get the
// relevant bits
- return alignTo(RequestedElts, 2) / 2;
+ return alignTo(RequestedElts, EltsPerReg) / EltsPerReg;
}
case TTI::SK_PermuteTwoSrc:
case TTI::SK_Splice:
case TTI::SK_Select: {
- unsigned NumPerms = alignTo(RequestedElts, 2) / 2;
+ unsigned NumPerms = alignTo(RequestedElts, EltsPerReg) / EltsPerReg;
// SK_Select just reuses the same mask
unsigned NumPermMasks = Kind == TTI::SK_Select ? 1 : NumPerms;
return NumPerms + NumPermMasks;
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h
index 01df2e6caaba1d..6d889dfa93786d 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h
@@ -117,6 +117,7 @@ class GCNTTIImpl final : public BasicTTIImplBase<GCNTTIImpl> {
return TTI::PSK_FastHardware;
}
+ unsigned getNumberOfParts(Type *Tp);
unsigned getNumberOfRegisters(unsigned RCID) const;
TypeSize getRegisterBitWidth(TargetTransformInfo::RegisterKind Vector) const;
unsigned getMinVectorRegisterBitWidth() const;
diff --git a/llvm/test/Analysis/CostModel/AMDGPU/shufflevector.ll b/llvm/test/Analysis/CostModel/AMDGPU/shufflevector.ll
index a18156744a36b1..adcabe70ec609e 100644
--- a/llvm/test/Analysis/CostModel/AMDGPU/shufflevector.ll
+++ b/llvm/test/Analysis/CostModel/AMDGPU/shufflevector.ll
@@ -396,157 +396,157 @@ define amdgpu_kernel void @shufflevector_i16(<2 x i16> %vec1, <2 x i16> %vec2) {
; Should not assert
define amdgpu_kernel void @shufflevector_i8(<2 x i8> %vec1, <2 x i8> %vec2) {
; ALL-LABEL: 'shufflevector_i8'
-; ALL-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %shuf00 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> zeroinitializer
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf00 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> zeroinitializer
; ALL-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %shuf01 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 0, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf10 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf11 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf10 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf11 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 1>
; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf02 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 0, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf20 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %shuf22 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf03 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 0, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf30 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf33 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf12 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf21 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %shuf20 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf22 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf03 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 0, i32 3>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf30 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf33 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 3>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf12 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf21 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 1>
; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf13 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 1, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf31 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf31 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 1>
; ALL-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %shuf23 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 2, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf32 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf000 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> zeroinitializer
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf001 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 0, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf010 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 1, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf011 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 1, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf100 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 0, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf101 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 0, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf110 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf111 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf002 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 0, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf020 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 2, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf022 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 2, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf200 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 0, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf202 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 0, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf220 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf222 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf112 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf121 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 2, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf122 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 2, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf211 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 1, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf212 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 1, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 6 for instruction: %shuf221 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %shuf00_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> zeroinitializer
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf32 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <2 x i32> <i32 3, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf000 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> zeroinitializer
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf001 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 0, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf010 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 1, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf011 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 1, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf100 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 0, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf101 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 0, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf110 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf111 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf002 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 0, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf020 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 2, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf022 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 0, i32 2, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf200 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 0, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf202 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 0, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf220 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf222 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf112 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 1, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf121 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 2, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf122 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 1, i32 2, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf211 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 1, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf212 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 1, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf221 = shufflevector <2 x i8> %vec1, <2 x i8> %vec1, <3 x i32> <i32 2, i32 2, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf00_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> zeroinitializer
; ALL-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %shuf01_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 0, i32 1>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf10_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf11_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf10_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf11_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 1>
; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf02_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 0, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf20_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %shuf22_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf03_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 0, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf30_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 3, i32 0>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf33_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 3, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf12_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 2>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf21_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %shuf20_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf22_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf03_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 0, i32 3>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf30_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 3, i32 0>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf33_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 3, i32 3>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf12_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 2>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf21_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 2, i32 1>
; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf13_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 1, i32 3>
-; ALL-NEXT: Cost Model: Found an estimated cost of 4 for instruction: %shuf31_2 = shufflevector <2 x i8> %vec1, <2 x i8> %vec2, <2 x i32> <i32 3, i32 1>
+; ALL-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %shuf31_2 = shufflevector <2...
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arsenm
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Oct 10, 2024
| define <4 x i8> @uadd_sat_v4i8(<4 x i8> %arg0, <4 x i8> %arg1, ptr addrspace(1) %dst) { | ||
| ; GCN-LABEL: @uadd_sat_v4i8( | ||
| ; GCN-NEXT: bb: | ||
| ; GCN-NEXT: [[TMP0:%.*]] = call <4 x i8> @llvm.uadd.sat.v4i8(<4 x i8> [[ARG0:%.*]], <4 x i8> [[ARG1:%.*]]) |
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This is a bad side effect: https://godbolt.org/z/aKxncz77e
I expect similar degradation for all of the other cases
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This is due to the calling convention, and is not regression of lowering @llvm.uadd.sat.v4i8 vs 4 x @llvm.uadd.sat.i8
The calling convention scalarizes i8 vectors similar to how we pass them across basic blocks. SLP cost model should account for the extracts needed for the vectorized version.
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| // For certain 8 bit ops, we can pack a v4i8 into a single part | ||
| // (e.g. v4i8 shufflevectors -> v_perm v4i8, v4i8). Thus, we |
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For certain ops, but this is much broader. It's only a few data flow ops where this might help, but this is making the costs of other operations too optimistic. We should avoid vectorizing non-dataflow operations.
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Ultimately, I still think it is the better approach to have SLP handle this type of vectorization (as opposed to writing a data-flow vectorizer). I think it should be left up to the cost model to accurately measure the quality and filter all but those few ops we are interested in. That was the intent of this PR, but it seems I'll need to tune the costs for calling convetion at least.
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I've added #113002 to vectorize i8s with a more refined cost model (instead of using shuffle vectorization to capture the usecase we are interested in)
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i8 shuffle vectors have standard isel dags and will be lowered into v_perms with CalculateByteProvider.
Moreever, if we are unconvinced by #95328 , enabling i8 shuffle vectorization should indirectly capture many of the needed vectorization cases for #66838 . In that sense, this PR sort of competes with #95328 , though it does have standalone merits.
This PR is meant for commits starting at b503e21 . Depends on #91016
Reopen of #95840