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[MLIR] Lower math.powf(x, 3.0) to x * x * x. #127256

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Merged
merged 1 commit into from
Feb 14, 2025
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[MLIR] Lower math.powf(x, 3.0) to x * x * x. #127256

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13 changes: 9 additions & 4 deletions mlir/lib/Dialect/Math/Transforms/ExpandPatterns.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -325,6 +325,9 @@ static LogicalResult convertPowfOp(math::PowFOp op, PatternRewriter &rewriter) {
auto &sem =
cast<mlir::FloatType>(getElementTypeOrSelf(typeB)).getFloatSemantics();
APFloat valueB(sem);
auto mulf = [&](Value x, Value y) -> Value {
return b.create<arith::MulFOp>(x, y);
};
if (matchPattern(operandB, m_ConstantFloat(&valueB))) {
if (valueB.isZero()) {
// a^0 -> 1
Expand Down Expand Up @@ -358,19 +361,21 @@ static LogicalResult convertPowfOp(math::PowFOp op, PatternRewriter &rewriter) {
}
if (valueB.isExactlyValue(2.0)) {
// a^2 -> a * a
Value mul = b.create<arith::MulFOp>(operandA, operandA);
rewriter.replaceOp(op, mul);
rewriter.replaceOp(op, mulf(operandA, operandA));
return success();
}
if (valueB.isExactlyValue(-2.0)) {
// a^(-2) -> 1 / (a * a)
Value mul = b.create<arith::MulFOp>(operandA, operandA);
Value one =
createFloatConst(op->getLoc(), operandA.getType(), 1.0, rewriter);
Value div = b.create<arith::DivFOp>(one, mul);
Value div = b.create<arith::DivFOp>(one, mulf(operandA, operandA));
rewriter.replaceOp(op, div);
return success();
}
if (valueB.isExactlyValue(3.0)) {
rewriter.replaceOp(op, mulf(mulf(operandA, operandA), operandA));
return success();
}
}

Value logA = b.create<math::LogOp>(operandA);
Expand Down
11 changes: 11 additions & 0 deletions mlir/test/Dialect/Math/expand-math.mlir
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Expand Up @@ -285,6 +285,17 @@ func.func @powf_func_negtwo(%a: f64) -> f64{
return %ret : f64
}

// CHECK-LABEL: func @powf_func_three
// CHECK-SAME: (%[[ARG0:.+]]: f64) -> f64
func.func @powf_func_three(%a: f64) -> f64{
// CHECK: %[[MUL:.+]] = arith.mulf %[[ARG0]], %[[ARG0]] : f64
// CHECK: %[[MUL2:.+]] = arith.mulf %[[MUL]], %[[ARG0]] : f64
// CHECK: return %[[MUL2]] : f64
%b = arith.constant 3.0 : f64
%ret = math.powf %a, %b : f64
return %ret : f64
}

// -----

// CHECK-LABEL: func.func @roundeven64
Expand Down