Skip to content

Commit

Permalink
Fix complex log1p accuracy with large abs values. (llvm#88260)
Browse files Browse the repository at this point in the history 
This ports openxla/xla#10503 by @pearu. The new
implementation matches mpmath's results for most inputs, see caveats in
the linked pull request. In addition to the filecheck test here, the
accuracy was tested with XLA's complex_unary_op_test and its MLIR
emitters.
  • Loading branch information
@jreiffers
jreiffers authored Apr 10, 2024
1 parent 1ca0195 commit 49ef12a
Show file tree
Hide file tree
Showing 2 changed files with 57 additions and 41 deletions.
50 changes: 26 additions & 24 deletions mlir/lib/Conversion/ComplexToStandard/ComplexToStandard.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -570,37 +570,39 @@ struct Log1pOpConversion : public OpConversionPattern<complex::Log1pOp> {
ConversionPatternRewriter &rewriter) const override {
auto type = cast<ComplexType>(adaptor.getComplex().getType());
auto elementType = cast<FloatType>(type.getElementType());
arith::FastMathFlagsAttr fmf = op.getFastMathFlagsAttr();
arith::FastMathFlags fmf = op.getFastMathFlagsAttr().getValue();
mlir::ImplicitLocOpBuilder b(op.getLoc(), rewriter);

Value real = b.create<complex::ReOp>(elementType, adaptor.getComplex());
Value imag = b.create<complex::ImOp>(elementType, adaptor.getComplex());
Value real = b.create<complex::ReOp>(adaptor.getComplex());
Value imag = b.create<complex::ImOp>(adaptor.getComplex());

Value half = b.create<arith::ConstantOp>(elementType,
b.getFloatAttr(elementType, 0.5));
Value one = b.create<arith::ConstantOp>(elementType,
b.getFloatAttr(elementType, 1));
Value two = b.create<arith::ConstantOp>(elementType,
b.getFloatAttr(elementType, 2));

// log1p(a+bi) = .5*log((a+1)^2+b^2) + i*atan2(b, a + 1)
// log((a+1)+bi) = .5*log(a*a + 2*a + 1 + b*b) + i*atan2(b, a+1)
// log((a+1)+bi) = .5*log1p(a*a + 2*a + b*b) + i*atan2(b, a+1)
Value sumSq = b.create<arith::MulFOp>(real, real, fmf.getValue());
sumSq = b.create<arith::AddFOp>(
sumSq, b.create<arith::MulFOp>(real, two, fmf.getValue()),
fmf.getValue());
sumSq = b.create<arith::AddFOp>(
sumSq, b.create<arith::MulFOp>(imag, imag, fmf.getValue()),
fmf.getValue());
Value logSumSq =
b.create<math::Log1pOp>(elementType, sumSq, fmf.getValue());
Value resultReal = b.create<arith::MulFOp>(logSumSq, half, fmf.getValue());

Value realPlusOne = b.create<arith::AddFOp>(real, one, fmf.getValue());

Value resultImag =
b.create<math::Atan2Op>(elementType, imag, realPlusOne, fmf.getValue());
Value realPlusOne = b.create<arith::AddFOp>(real, one, fmf);
Value absRealPlusOne = b.create<math::AbsFOp>(realPlusOne, fmf);
Value absImag = b.create<math::AbsFOp>(imag, fmf);

Value maxAbs = b.create<arith::MaximumFOp>(absRealPlusOne, absImag, fmf);
Value minAbs = b.create<arith::MinimumFOp>(absRealPlusOne, absImag, fmf);

Value maxAbsOfRealPlusOneAndImagMinusOne = b.create<arith::SelectOp>(
b.create<arith::CmpFOp>(arith::CmpFPredicate::OGT, realPlusOne, absImag,
fmf),
real, b.create<arith::SubFOp>(maxAbs, one, fmf));
Value minMaxRatio = b.create<arith::DivFOp>(minAbs, maxAbs, fmf);
Value logOfMaxAbsOfRealPlusOneAndImag =
b.create<math::Log1pOp>(maxAbsOfRealPlusOneAndImagMinusOne, fmf);
Value logOfSqrtPart = b.create<math::Log1pOp>(
b.create<arith::MulFOp>(minMaxRatio, minMaxRatio, fmf), fmf);
Value r = b.create<arith::AddFOp>(
b.create<arith::MulFOp>(half, logOfSqrtPart, fmf),
logOfMaxAbsOfRealPlusOneAndImag, fmf);
Value resultReal = b.create<arith::SelectOp>(
b.create<arith::CmpFOp>(arith::CmpFPredicate::UNO, r, r, fmf), minAbs,
r);
Value resultImag = b.create<math::Atan2Op>(imag, realPlusOne, fmf);
rewriter.replaceOpWithNewOp<complex::CreateOp>(op, type, resultReal,
resultImag);
return success();
Expand Down
48 changes: 31 additions & 17 deletions mlir/test/Conversion/ComplexToStandard/convert-to-standard.mlir
View file
Original file line number Diff line number Diff line change
Expand Up @@ -300,15 +300,22 @@ func.func @complex_log1p(%arg: complex<f32>) -> complex<f32> {
// CHECK: %[[IMAG:.*]] = complex.im %[[ARG]] : complex<f32>
// CHECK: %[[ONE_HALF:.*]] = arith.constant 5.000000e-01 : f32
// CHECK: %[[ONE:.*]] = arith.constant 1.000000e+00 : f32
// CHECK: %[[TWO:.*]] = arith.constant 2.000000e+00 : f32
// CHECK: %[[SQ_SUM_0:.*]] = arith.mulf %[[REAL]], %[[REAL]] : f32
// CHECK: %[[TWO_REAL:.*]] = arith.mulf %[[REAL]], %[[TWO]] : f32
// CHECK: %[[SQ_SUM_1:.*]] = arith.addf %[[SQ_SUM_0]], %[[TWO_REAL]] : f32
// CHECK: %[[SQ_IMAG:.*]] = arith.mulf %[[IMAG]], %[[IMAG]] : f32
// CHECK: %[[SQ_SUM_2:.*]] = arith.addf %[[SQ_SUM_1]], %[[SQ_IMAG]] : f32
// CHECK: %[[LOG_SQ_SUM:.*]] = math.log1p %[[SQ_SUM_2]] : f32
// CHECK: %[[RESULT_REAL:.*]] = arith.mulf %[[LOG_SQ_SUM]], %[[ONE_HALF]] : f32
// CHECK: %[[REAL_PLUS_ONE:.*]] = arith.addf %[[REAL]], %[[ONE]] : f32
// CHECK: %[[ABS_REAL_PLUS_ONE:.*]] = math.absf %[[REAL_PLUS_ONE]] : f32
// CHECK: %[[ABS_IMAG:.*]] = math.absf %[[IMAG]] : f32
// CHECK: %[[MAX:.*]] = arith.maximumf %[[ABS_REAL_PLUS_ONE]], %[[ABS_IMAG]] : f32
// CHECK: %[[MIN:.*]] = arith.minimumf %[[ABS_REAL_PLUS_ONE]], %[[ABS_IMAG]] : f32
// CHECK: %[[CMPF:.*]] = arith.cmpf ogt, %[[REAL_PLUS_ONE]], %[[ABS_IMAG]] : f32
// CHECK: %[[MAX_MINUS_ONE:.*]] = arith.subf %[[MAX]], %cst_0 : f32
// CHECK: %[[SELECT:.*]] = arith.select %[[CMPF]], %0, %[[MAX_MINUS_ONE]] : f32
// CHECK: %[[MIN_MAX_RATIO:.*]] = arith.divf %[[MIN]], %[[MAX]] : f32
// CHECK: %[[LOG_1:.*]] = math.log1p %[[SELECT]] : f32
// CHECK: %[[RATIO_SQ:.*]] = arith.mulf %[[MIN_MAX_RATIO]], %[[MIN_MAX_RATIO]] : f32
// CHECK: %[[LOG_SQ:.*]] = math.log1p %[[RATIO_SQ]] : f32
// CHECK: %[[HALF_LOG_SQ:.*]] = arith.mulf %cst, %[[LOG_SQ]] : f32
// CHECK: %[[R:.*]] = arith.addf %[[HALF_LOG_SQ]], %[[LOG_1]] : f32
// CHECK: %[[ISNAN:.*]] = arith.cmpf uno, %[[R]], %[[R]] : f32
// CHECK: %[[RESULT_REAL:.*]] = arith.select %[[ISNAN]], %[[MIN]], %[[R]] : f32
// CHECK: %[[RESULT_IMAG:.*]] = math.atan2 %[[IMAG]], %[[REAL_PLUS_ONE]] : f32
// CHECK: %[[RESULT:.*]] = complex.create %[[RESULT_REAL]], %[[RESULT_IMAG]] : complex<f32>
// CHECK: return %[[RESULT]] : complex<f32>
Expand Down Expand Up @@ -963,15 +970,22 @@ func.func @complex_log1p_with_fmf(%arg: complex<f32>) -> complex<f32> {
// CHECK: %[[IMAG:.*]] = complex.im %[[ARG]] : complex<f32>
// CHECK: %[[ONE_HALF:.*]] = arith.constant 5.000000e-01 : f32
// CHECK: %[[ONE:.*]] = arith.constant 1.000000e+00 : f32
// CHECK: %[[TWO:.*]] = arith.constant 2.000000e+00 : f32
// CHECK: %[[SQ_SUM_0:.*]] = arith.mulf %[[REAL]], %[[REAL]] fastmath<nnan,contract> : f32
// CHECK: %[[TWO_REAL:.*]] = arith.mulf %[[REAL]], %[[TWO]] fastmath<nnan,contract> : f32
// CHECK: %[[SQ_SUM_1:.*]] = arith.addf %[[SQ_SUM_0]], %[[TWO_REAL]] fastmath<nnan,contract> : f32
// CHECK: %[[SQ_IMAG:.*]] = arith.mulf %[[IMAG]], %[[IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[SQ_SUM_2:.*]] = arith.addf %[[SQ_SUM_1]], %[[SQ_IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[LOG_SQ_SUM:.*]] = math.log1p %[[SQ_SUM_2]] fastmath<nnan,contract> : f32
// CHECK: %[[RESULT_REAL:.*]] = arith.mulf %[[LOG_SQ_SUM]], %[[ONE_HALF]] fastmath<nnan,contract> : f32
// CHECK: %[[REAL_PLUS_ONE:.*]] = arith.addf %[[REAL]], %[[ONE]] fastmath<nnan,contract> : f32
// CHECK: %[[REAL_PLUS_ONE:.*]] = arith.addf %[[REAL]], %[[ONE]] fastmath<nnan,contract> : f32
// CHECK: %[[ABS_REAL_PLUS_ONE:.*]] = math.absf %[[REAL_PLUS_ONE]] fastmath<nnan,contract> : f32
// CHECK: %[[ABS_IMAG:.*]] = math.absf %[[IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[MAX:.*]] = arith.maximumf %[[ABS_REAL_PLUS_ONE]], %[[ABS_IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[MIN:.*]] = arith.minimumf %[[ABS_REAL_PLUS_ONE]], %[[ABS_IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[CMPF:.*]] = arith.cmpf ogt, %[[REAL_PLUS_ONE]], %[[ABS_IMAG]] fastmath<nnan,contract> : f32
// CHECK: %[[MAX_MINUS_ONE:.*]] = arith.subf %[[MAX]], %cst_0 fastmath<nnan,contract> : f32
// CHECK: %[[SELECT:.*]] = arith.select %[[CMPF]], %0, %[[MAX_MINUS_ONE]] : f32
// CHECK: %[[MIN_MAX_RATIO:.*]] = arith.divf %[[MIN]], %[[MAX]] fastmath<nnan,contract> : f32
// CHECK: %[[LOG_1:.*]] = math.log1p %[[SELECT]] fastmath<nnan,contract> : f32
// CHECK: %[[RATIO_SQ:.*]] = arith.mulf %[[MIN_MAX_RATIO]], %[[MIN_MAX_RATIO]] fastmath<nnan,contract> : f32
// CHECK: %[[LOG_SQ:.*]] = math.log1p %[[RATIO_SQ]] fastmath<nnan,contract> : f32
// CHECK: %[[HALF_LOG_SQ:.*]] = arith.mulf %cst, %[[LOG_SQ]] fastmath<nnan,contract> : f32
// CHECK: %[[R:.*]] = arith.addf %[[HALF_LOG_SQ]], %[[LOG_1]] fastmath<nnan,contract> : f32
// CHECK: %[[ISNAN:.*]] = arith.cmpf uno, %[[R]], %[[R]] fastmath<nnan,contract> : f32
// CHECK: %[[RESULT_REAL:.*]] = arith.select %[[ISNAN]], %[[MIN]], %[[R]] : f32
// CHECK: %[[RESULT_IMAG:.*]] = math.atan2 %[[IMAG]], %[[REAL_PLUS_ONE]] fastmath<nnan,contract> : f32
// CHECK: %[[RESULT:.*]] = complex.create %[[RESULT_REAL]], %[[RESULT_IMAG]] : complex<f32>
// CHECK: return %[[RESULT]] : complex<f32>
Expand Down

0 comments on commit 49ef12a

Please sign in to comment.