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[Matrix] Lower vector reductions using shape info #142055

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84ff8f4
pre-land reduce.ll
jroelofs Jun 23, 2025
aff9068
[Matrix] Lower vector reductions using shape info
jroelofs Jun 23, 2025
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154 changes: 153 additions & 1 deletion llvm/lib/Transforms/Scalar/LowerMatrixIntrinsics.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
Expand All @@ -41,6 +42,7 @@
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/MatrixBuilder.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/CommandLine.h"
Expand Down Expand Up @@ -325,6 +327,25 @@ computeShapeInfoForInst(Instruction *I,
return OpShape->second;
}

if (auto *II = dyn_cast<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) {
case Intrinsic::vector_reduce_fadd:
case Intrinsic::vector_reduce_fmul:
case Intrinsic::vector_reduce_fmax:
case Intrinsic::vector_reduce_fmaximum:
case Intrinsic::vector_reduce_fmin:
case Intrinsic::vector_reduce_fminimum:
case Intrinsic::vector_reduce_add:
case Intrinsic::vector_reduce_and:
case Intrinsic::vector_reduce_mul:
case Intrinsic::vector_reduce_or:
case Intrinsic::vector_reduce_xor:
return ShapeInfo(1, 1);
default:
break;
}
}

if (isUniformShape(I) || isa<SelectInst>(I)) {
auto Ops = I->operands();
auto ShapedOps = isa<SelectInst>(I) ? drop_begin(Ops) : Ops;
Expand Down Expand Up @@ -468,7 +489,7 @@ class LowerMatrixIntrinsics {
return make_range(Vectors.begin(), Vectors.end());
}

iterator_range<SmallVector<Value *, 8>::iterator> vectors() {
iterator_range<SmallVector<Value *, 8>::const_iterator> vectors() const {
return make_range(Vectors.begin(), Vectors.end());
}

Expand Down Expand Up @@ -701,7 +722,31 @@ class LowerMatrixIntrinsics {
case Intrinsic::matrix_transpose:
case Intrinsic::matrix_column_major_load:
case Intrinsic::matrix_column_major_store:
case Intrinsic::vector_reduce_fmax:
case Intrinsic::vector_reduce_fmaximum:
case Intrinsic::vector_reduce_fmin:
case Intrinsic::vector_reduce_fminimum:
case Intrinsic::vector_reduce_add:
case Intrinsic::vector_reduce_and:
case Intrinsic::vector_reduce_mul:
case Intrinsic::vector_reduce_or:
case Intrinsic::vector_reduce_xor:
return true;
case Intrinsic::vector_reduce_fadd:
case Intrinsic::vector_reduce_fmul: {
FastMathFlags FMF = getFastMathFlags(Inst);
if (Inst->getType()->isFloatingPointTy() && !FMF.allowReassoc())
return false;

if (match(Inst, m_Intrinsic<Intrinsic::vector_reduce_fadd>(
m_Unless(m_AnyZeroFP()), m_Value())))
return false;

if (match(Inst, m_Intrinsic<Intrinsic::vector_reduce_fmul>(
m_Unless(m_FPOne()), m_Value())))
return false;
return true;
}
default:
return isUniformShape(II);
}
Expand Down Expand Up @@ -1268,6 +1313,113 @@ class LowerMatrixIntrinsics {
return Result.addNumComputeOps(getNumOps(Result.getVectorTy()) *
Result.getNumVectors());
}
case Intrinsic::vector_reduce_fadd: {
Builder.setFastMathFlags(getFastMathFlags(Inst));
auto *I = Inst2ColumnMatrix.find(Inst->getOperand(1));
assert(I != Inst2ColumnMatrix.end());
const MatrixTy &M = I->second;

Value *Start = Inst->getOperand(0);
Value *ResultV = Builder.CreateVectorSplat(
ElementCount::getFixed(M.getStride()), Start);
for (auto &Vector : M.vectors())
ResultV = Builder.CreateFAdd(ResultV, Vector);

Value *Result = Builder.CreateFAddReduce(Start, ResultV);
Inst->replaceAllUsesWith(Result);
Result->takeName(Inst);
return MatrixTy{Result};
} break;
case Intrinsic::vector_reduce_fmul: {
Builder.setFastMathFlags(getFastMathFlags(Inst));
auto *I = Inst2ColumnMatrix.find(Inst->getOperand(1));
assert(I != Inst2ColumnMatrix.end());
const MatrixTy &M = I->second;

Value *Start = Inst->getOperand(0);
Value *ResultV = Builder.CreateVectorSplat(
ElementCount::getFixed(M.getStride()), Start);
for (auto &Vector : M.vectors())
ResultV = Builder.CreateFMul(ResultV, Vector);

Value *Result = Builder.CreateFMulReduce(Start, ResultV);
Inst->replaceAllUsesWith(Result);
Result->takeName(Inst);
return MatrixTy{Result};
} break;
case Intrinsic::vector_reduce_fmax:
case Intrinsic::vector_reduce_fmaximum:
case Intrinsic::vector_reduce_fmin:
case Intrinsic::vector_reduce_fminimum:
case Intrinsic::vector_reduce_add:
case Intrinsic::vector_reduce_and:
case Intrinsic::vector_reduce_mul:
case Intrinsic::vector_reduce_or:
case Intrinsic::vector_reduce_xor: {
Builder.setFastMathFlags(getFastMathFlags(Inst));
auto *I = Inst2ColumnMatrix.find(Inst->getOperand(0));
assert(I != Inst2ColumnMatrix.end());
const MatrixTy &M = I->second;

auto CreateVReduce = [&](Value *LHS, Value *RHS) {
switch (Inst->getIntrinsicID()) {
case Intrinsic::vector_reduce_add:
return Builder.CreateAdd(LHS, RHS);
case Intrinsic::vector_reduce_and:
return Builder.CreateAnd(LHS, RHS);
case Intrinsic::vector_reduce_fmax:
return Builder.CreateMaximum(LHS, RHS);
case Intrinsic::vector_reduce_fmaximum:
return Builder.CreateMaximumNum(LHS, RHS);
case Intrinsic::vector_reduce_fmin:
return Builder.CreateMinimum(LHS, RHS);
case Intrinsic::vector_reduce_fminimum:
return Builder.CreateMinimumNum(LHS, RHS);
case Intrinsic::vector_reduce_mul:
return Builder.CreateMul(LHS, RHS);
case Intrinsic::vector_reduce_or:
return Builder.CreateOr(LHS, RHS);
case Intrinsic::vector_reduce_xor:
return Builder.CreateXor(LHS, RHS);
default:
llvm_unreachable("unexpected intrinsic");
}
};

Value *ResultV = M.getVector(0);
for (auto &Vector : drop_begin(M.vectors()))
ResultV = CreateVReduce(ResultV, Vector);

auto CreateHReduce = [&](Value *V) {
switch (Inst->getIntrinsicID()) {
case Intrinsic::vector_reduce_add:
return Builder.CreateAddReduce(V);
case Intrinsic::vector_reduce_and:
return Builder.CreateAndReduce(V);
case Intrinsic::vector_reduce_fmax:
return Builder.CreateFPMaxReduce(V);
case Intrinsic::vector_reduce_fmaximum:
return Builder.CreateFPMaximumReduce(V);
case Intrinsic::vector_reduce_fmin:
return Builder.CreateFPMinReduce(V);
case Intrinsic::vector_reduce_fminimum:
return Builder.CreateFPMinimumReduce(V);
case Intrinsic::vector_reduce_mul:
return Builder.CreateMulReduce(V);
case Intrinsic::vector_reduce_or:
return Builder.CreateOrReduce(V);
case Intrinsic::vector_reduce_xor:
return Builder.CreateXorReduce(V);
default:
llvm_unreachable("unexpected intrinsic");
}
};

Value *Result = CreateHReduce(ResultV);
Inst->replaceAllUsesWith(Result);
Result->takeName(Inst);
return MatrixTy{Result};
} break;
default:
break;
}
Expand Down
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