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[TTI] Support scalable offsets in getScalingFactorCost #88113

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Merged
merged 4 commits into from
May 10, 2024
Merged

[TTI] Support scalable offsets in getScalingFactorCost #88113

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49ee8d7
[TTI] Support scalable offsets in getScalingFactorCost
huntergr-arm Apr 3, 2024
2a61c4d
Switch to StackOffset
huntergr-arm Apr 23, 2024
5228db4
Don't assert for scalable offsets for other targets
huntergr-arm May 8, 2024
10a454a
Remove unnecessary friend class declaration
huntergr-arm May 8, 2024
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6 changes: 3 additions & 3 deletions llvm/include/llvm/Analysis/TargetTransformInfo.h
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Expand Up @@ -834,7 +834,7 @@ class TargetTransformInfo {
/// If the AM is not supported, it returns a negative value.
/// TODO: Handle pre/postinc as well.
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
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It seems we now have three approaches for passing a 'scalable' and a 'fixed-length' offset to interfaces for this:

  1. One using StackOffset (this patch for getScalingFactorCost)
  2. One passing in two separate variables (isLegalAddressingMode)
  3. Another one with two separate interfaces (isLegalAddImmediate vs isLegalAddScalableImmediate)

It would be good to settle on a single approach. @paulwalker-arm is there a particular reason you're pushing for (1) for this interface?

If we go for (1), I think we should rename StackOffset to MemOffset to make it more generic, because in this instance the offset does not necessarily apply only to stack addresses.

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I made my request because the function was changed to take both a fixed-length and a scalar offset, which is exactly why StackOffset exists (albeit, as you say, with a name that's now out of date). I think all offset related common code interfaces should be unified to accept the fact they can be fixed or scaled and thus use whichever of the TypeSize.h family of types that best fits the specific need. I'll note we are missing a generic type like TypeSize but signed, to make this truly possible.

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FWIW, my original patches did have a new type like that -- I originally called it AddressOffset, then TargetImmediate. I got some feedback that separating the terms out might be better, so we ended up with different int64_ts.

If we end up with an address formula with both fixed and scalable immediate terms, we'll have to prioritize one over the for a given target other due to the way LSR currently forms the Uses it will evaluate. AFAIK nobody implements instructions with mixed fixed and scalable immediates, so one or the other immediate would need to become part of the base for that formula.

int64_t Scale,
unsigned AddrSpace = 0) const;

Expand Down Expand Up @@ -1891,7 +1891,7 @@ class TargetTransformInfo::Concept {
virtual bool hasVolatileVariant(Instruction *I, unsigned AddrSpace) = 0;
virtual bool prefersVectorizedAddressing() = 0;
virtual InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset,
StackOffset BaseOffset,
bool HasBaseReg, int64_t Scale,
unsigned AddrSpace) = 0;
virtual bool LSRWithInstrQueries() = 0;
Expand Down Expand Up @@ -2403,7 +2403,7 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
return Impl.prefersVectorizedAddressing();
}
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale,
unsigned AddrSpace) override {
return Impl.getScalingFactorCost(Ty, BaseGV, BaseOffset, HasBaseReg, Scale,
Expand Down
8 changes: 5 additions & 3 deletions llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
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Expand Up @@ -32,6 +32,7 @@ class Function;
/// Base class for use as a mix-in that aids implementing
/// a TargetTransformInfo-compatible class.
class TargetTransformInfoImplBase {

protected:
typedef TargetTransformInfo TTI;

Expand Down Expand Up @@ -326,12 +327,13 @@ class TargetTransformInfoImplBase {
bool prefersVectorizedAddressing() const { return true; }

InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale,
unsigned AddrSpace) const {
// Guess that all legal addressing mode are free.
if (isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg, Scale,
AddrSpace))
if (isLegalAddressingMode(Ty, BaseGV, BaseOffset.getFixed(), HasBaseReg,
Scale, AddrSpace, /*I=*/nullptr,
BaseOffset.getScalable()))
return 0;
return -1;
}
Expand Down
5 changes: 3 additions & 2 deletions llvm/include/llvm/CodeGen/BasicTTIImpl.h
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Expand Up @@ -403,13 +403,14 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
}

InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) {
TargetLoweringBase::AddrMode AM;
AM.BaseGV = BaseGV;
AM.BaseOffs = BaseOffset;
AM.BaseOffs = BaseOffset.getFixed();
AM.HasBaseReg = HasBaseReg;
AM.Scale = Scale;
AM.ScalableOffset = BaseOffset.getScalable();
if (getTLI()->isLegalAddressingMode(DL, AM, Ty, AddrSpace))
return 0;
return -1;
Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/Analysis/TargetTransformInfo.cpp
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Expand Up @@ -531,7 +531,7 @@ bool TargetTransformInfo::prefersVectorizedAddressing() const {
}

InstructionCost TargetTransformInfo::getScalingFactorCost(
Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset, bool HasBaseReg,
Type *Ty, GlobalValue *BaseGV, StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const {
InstructionCost Cost = TTIImpl->getScalingFactorCost(
Ty, BaseGV, BaseOffset, HasBaseReg, Scale, AddrSpace);
Expand Down
5 changes: 3 additions & 2 deletions llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
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Expand Up @@ -4162,7 +4162,7 @@ bool AArch64TTIImpl::preferPredicateOverEpilogue(TailFoldingInfo *TFI) {

InstructionCost
AArch64TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const {
// Scaling factors are not free at all.
// Operands | Rt Latency
Expand All @@ -4173,9 +4173,10 @@ AArch64TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
// Rt, [Xn, Wm, <extend> #imm] |
TargetLoweringBase::AddrMode AM;
AM.BaseGV = BaseGV;
AM.BaseOffs = BaseOffset;
AM.BaseOffs = BaseOffset.getFixed();
AM.HasBaseReg = HasBaseReg;
AM.Scale = Scale;
AM.ScalableOffset = BaseOffset.getScalable();
if (getTLI()->isLegalAddressingMode(DL, AM, Ty, AddrSpace))
// Scale represents reg2 * scale, thus account for 1 if
// it is not equal to 0 or 1.
Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h
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Expand Up @@ -407,7 +407,7 @@ class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, it returns a negative value.
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const;
/// @}

Expand Down
5 changes: 3 additions & 2 deletions llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
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Expand Up @@ -2571,14 +2571,15 @@ bool ARMTTIImpl::preferPredicatedReductionSelect(
}

InstructionCost ARMTTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset,
StackOffset BaseOffset,
bool HasBaseReg, int64_t Scale,
unsigned AddrSpace) const {
TargetLoweringBase::AddrMode AM;
AM.BaseGV = BaseGV;
AM.BaseOffs = BaseOffset;
AM.BaseOffs = BaseOffset.getFixed();
AM.HasBaseReg = HasBaseReg;
AM.Scale = Scale;
AM.ScalableOffset = BaseOffset.getScalable();
if (getTLI()->isLegalAddressingMode(DL, AM, Ty, AddrSpace)) {
if (ST->hasFPAO())
return AM.Scale < 0 ? 1 : 0; // positive offsets execute faster
Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/Target/ARM/ARMTargetTransformInfo.h
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Expand Up @@ -303,7 +303,7 @@ class ARMTTIImpl : public BasicTTIImplBase<ARMTTIImpl> {
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, the return value must be negative.
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const;

bool maybeLoweredToCall(Instruction &I);
Expand Down
5 changes: 3 additions & 2 deletions llvm/lib/Target/X86/X86TargetTransformInfo.cpp
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Expand Up @@ -6708,7 +6708,7 @@ InstructionCost X86TTIImpl::getInterleavedMemoryOpCost(
}

InstructionCost X86TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset,
StackOffset BaseOffset,
bool HasBaseReg, int64_t Scale,
unsigned AddrSpace) const {
// Scaling factors are not free at all.
Expand All @@ -6731,9 +6731,10 @@ InstructionCost X86TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
// vmovaps %ymm1, (%r8) can use port 2, 3, or 7.
TargetLoweringBase::AddrMode AM;
AM.BaseGV = BaseGV;
AM.BaseOffs = BaseOffset;
AM.BaseOffs = BaseOffset.getFixed();
AM.HasBaseReg = HasBaseReg;
AM.Scale = Scale;
AM.ScalableOffset = BaseOffset.getScalable();
if (getTLI()->isLegalAddressingMode(DL, AM, Ty, AddrSpace))
// Scale represents reg2 * scale, thus account for 1
// as soon as we use a second register.
Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/Target/X86/X86TargetTransformInfo.h
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Expand Up @@ -253,7 +253,7 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, it returns a negative value.
InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
StackOffset BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace) const;

bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
Expand Down
6 changes: 4 additions & 2 deletions llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
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Expand Up @@ -1817,10 +1817,12 @@ static InstructionCost getScalingFactorCost(const TargetTransformInfo &TTI,
case LSRUse::Address: {
// Check the scaling factor cost with both the min and max offsets.
InstructionCost ScaleCostMinOffset = TTI.getScalingFactorCost(
LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MinOffset, F.HasBaseReg,
LU.AccessTy.MemTy, F.BaseGV,
StackOffset::getFixed(F.BaseOffset + LU.MinOffset), F.HasBaseReg,
F.Scale, LU.AccessTy.AddrSpace);
InstructionCost ScaleCostMaxOffset = TTI.getScalingFactorCost(
LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MaxOffset, F.HasBaseReg,
LU.AccessTy.MemTy, F.BaseGV,
StackOffset::getFixed(F.BaseOffset + LU.MaxOffset), F.HasBaseReg,
F.Scale, LU.AccessTy.AddrSpace);

assert(ScaleCostMinOffset.isValid() && ScaleCostMaxOffset.isValid() &&
Expand Down
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