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[MooreToCore] Lower exponentiation to math.ipowi (PowSOpConversion) #8574

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Merged
merged 6 commits into from
Jul 1, 2025
Merged

[MooreToCore] Lower exponentiation to math.ipowi (PowSOpConversion) #8574

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c81f261
2025/06/17
liamslj13 Jun 17, 2025
39bbcbc
2025/06/17
liamslj13 Jun 17, 2025
fd17f74
MooreToCore.cpp/Passes.td Modifications
liamslj13 Jun 18, 2025
51e763f
MooreToCore.cpp/basic.mlir
liamslj13 Jun 20, 2025
f90c67f
test/Conversion/MooreToCore/basic.mlir
liamslj13 Jun 28, 2025
b12d0b8
lib/Conversion/MooreToCore/MooreToCore.cpp
liamslj13 Jul 1, 2025
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1 change: 1 addition & 0 deletions include/circt/Conversion/Passes.td
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Original file line number Diff line number Diff line change
Expand Up @@ -533,6 +533,7 @@ def ConvertMooreToCore : Pass<"convert-moore-to-core", "mlir::ModuleOp"> {
"llhd::LLHDDialect",
"mlir::cf::ControlFlowDialect",
"mlir::scf::SCFDialect",
"mlir::math::MathDialect",
"sim::SimDialect",
"verif::VerifDialect",
];
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36 changes: 6 additions & 30 deletions lib/Conversion/MooreToCore/MooreToCore.cpp
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Expand Up @@ -22,6 +22,7 @@
#include "mlir/Conversion/SCFToControlFlow/SCFToControlFlow.h"
#include "mlir/Dialect/ControlFlow/IR/ControlFlowOps.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/Math/IR/Math.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/IR/BuiltinDialect.h"
#include "mlir/IR/Iterators.h"
Expand Down Expand Up @@ -1358,36 +1359,10 @@ struct PowSOpConversion : public OpConversionPattern<PowSOp> {
Type resultType = typeConverter->convertType(op.getResult().getType());

Location loc = op.getLoc();
auto intType = cast<IntType>(op.getRhs().getType());
// transform a ** b into scf.for 0 to b step 1 { init *= a }, init = 1
Type integerType = rewriter.getIntegerType(intType.getWidth());
Value lhsVal = rewriter.create<ConversionOp>(loc, resultType, op.getLhs());
Value rhsVal = rewriter.create<ConversionOp>(loc, integerType, op.getRhs());
Value constZero = rewriter.create<hw::ConstantOp>(loc, integerType, 0);
Value constZeroResult = rewriter.create<hw::ConstantOp>(loc, resultType, 0);
Value isNegative = rewriter.create<comb::ICmpOp>(loc, ICmpPredicate::slt,
rhsVal, constZero);

// if the exponent is negative, return 0
lhsVal =
rewriter.create<comb::MuxOp>(loc, isNegative, constZeroResult, lhsVal);
Value upperBound =
rewriter.create<comb::MuxOp>(loc, isNegative, constZero, rhsVal);

Value lowerBound = constZero;
Value step = rewriter.create<hw::ConstantOp>(loc, integerType, 1);
Value initVal = rewriter.create<hw::ConstantOp>(loc, resultType, 1);

auto forOp = rewriter.create<scf::ForOp>(
loc, lowerBound, upperBound, step, ValueRange(initVal),
[&](OpBuilder &builder, Location loc, Value i, ValueRange iterArgs) {
auto loopVar = iterArgs.front();
auto mul = rewriter.create<comb::MulOp>(loc, lhsVal, loopVar);
rewriter.create<scf::YieldOp>(loc, ValueRange(mul));
});

rewriter.replaceOp(op, forOp.getResult(0));

// utilize MLIR math dialect's math.ipowi to handle the exponentiation of
// expression
rewriter.replaceOpWithNewOp<mlir::math::IPowIOp>(
op, resultType, adaptor.getLhs(), adaptor.getRhs());
return success();
}
};
Expand Down Expand Up @@ -1631,6 +1606,7 @@ static void populateLegality(ConversionTarget &target,
target.addLegalDialect<hw::HWDialect>();
target.addLegalDialect<llhd::LLHDDialect>();
target.addLegalDialect<mlir::BuiltinDialect>();
target.addLegalDialect<mlir::math::MathDialect>();
target.addLegalDialect<sim::SimDialect>();
target.addLegalDialect<verif::VerifDialect>();

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22 changes: 5 additions & 17 deletions test/Conversion/MooreToCore/basic.mlir
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Expand Up @@ -1120,13 +1120,7 @@ func.func @PowUOp(%arg0: !moore.l32, %arg1: !moore.l32) {

// CHECK-LABEL: func.func @PowSOp
func.func @PowSOp(%arg0: !moore.i32, %arg1: !moore.i32) {
// CHECK: [[COND:%.+]] = comb.icmp slt %arg1, %{{.*}} : i32
// CHECK: [[BASE:%.+]] = comb.mux [[COND]], %{{.*}}, %arg0 : i32
// CHECK: [[EXP:%.+]] = comb.mux [[COND]], %{{.*}}, %arg1 : i32

// CHECK: %{{.*}} = scf.for %{{.*}} = %{{.*}} to [[EXP]] step %{{.*}} iter_args([[VAR:%.+]] = %{{.*}}) -> (i32) : i32 {
// CHECK: [[MUL:%.+]] = comb.mul [[BASE]], [[VAR]] : i32
// CHECK: scf.yield [[MUL]] : i32
// CHECK: %[[RES:.*]] = math.ipowi %arg0, %arg1 : i32
%0 = moore.pows %arg0, %arg1 : i32
return
}
Expand All @@ -1149,15 +1143,9 @@ moore.module @blockArgAsObservedValue(in %in0: !moore.i32, in %in1: !moore.i32)
// CHECK: [[PRB:%.+]] = llhd.prb %var : !hw.inout<i32>
// CHECK: llhd.process
moore.procedure always_comb {
// CHECK: ^bb1: // 2 preds: ^bb0, ^bb5
// CHECK: [[COND:%.+]] = comb.icmp slt %in1, %{{.*}} : i32
// CHECK: comb.mux [[COND]], %{{.*}}, %in0 : i32
// CHECK: comb.mux [[COND]], %{{.*}}, %in1 : i32
%0 = moore.pows %in0, %in1 : !moore.i32
moore.blocking_assign %var, %0 : !moore.i32

// CHECK: ^bb5: // pred: ^bb4
// CHECK: llhd.wait (%in0, %in1, [[PRB]] : i32, i32, i32), ^bb1
moore.return
%0 = moore.add %in0, %in1 : !moore.i32
moore.blocking_assign %var, %0 : !moore.i32
// CHECK: llhd.wait (%in0, %in1, [[PRB]] : i32, i32, i32), ^bb1
moore.return
}
}