mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-14 11:32:34 +00:00
Add support for floating-point calculations of log2 with limited precisions of 6
and 18. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55968 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
parent
2379089a6e
commit
3eb594013f
@ -2755,7 +2755,6 @@ SelectionDAGLowering::implVisitBinaryAtomic(CallInst& I, ISD::NodeType Op) {
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/// visitExp - lower an exp intrinsic. Handles the special sequences
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/// for limited-precision mode.
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void
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SelectionDAGLowering::visitExp(CallInst &I) {
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SDValue result;
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@ -2768,7 +2767,6 @@ SelectionDAGLowering::visitExp(CallInst &I) {
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/// visitLog - lower a log intrinsic. Handles the special sequences
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/// for limited-precision mode.
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void
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SelectionDAGLowering::visitLog(CallInst &I) {
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SDValue result;
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@ -2779,108 +2777,225 @@ SelectionDAGLowering::visitLog(CallInst &I) {
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setValue(&I, result);
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}
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/// visitLog2 - lower a log2 intrinsic. Handles the special sequences
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/// for limited-precision mode.
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/// visitLog2 - Lower a log2 intrinsic. Handles the special sequences for
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/// limited-precision mode.
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void
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SelectionDAGLowering::visitLog2(CallInst &I) {
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SDValue result;
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if (getValue(I.getOperand(1)).getValueType() == MVT::f32 &&
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LimitFloatPrecision>0 && LimitFloatPrecision<=12) {
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SDValue operand = getValue(I.getOperand(1));
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SDValue operand1 = DAG.getNode(ISD::BIT_CONVERT, MVT::i32, operand);
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SDValue t0 = DAG.getNode(ISD::SRL, MVT::i32, operand1,
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DAG.getConstant(23, MVT::i32));
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SDValue t1 = DAG.getNode(ISD::AND, MVT::i32, t0,
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DAG.getConstant(255, MVT::i32));
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LimitFloatPrecision > 0 && LimitFloatPrecision <= 18) {
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SDValue Op = getValue(I.getOperand(1));
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SDValue Op1 = DAG.getNode(ISD::BIT_CONVERT, MVT::i32, Op);
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// Get the exponent, which is most of log and scale by log(2):
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//
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// LogOfExponent = (float) (((Op1 & 0x7f800000) >> 23) - 127);
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//
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// where Op1 is the hexidecimal representation of floating point value.
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SDValue t0 = DAG.getNode(ISD::AND, MVT::i32, Op1,
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DAG.getConstant(0x7f800000, MVT::i32));
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SDValue t1 = DAG.getNode(ISD::SRL, MVT::i32, t0,
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DAG.getConstant(23, MVT::i32));
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SDValue t2 = DAG.getNode(ISD::SUB, MVT::i32, t1,
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DAG.getConstant(127, MVT::i32));
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SDValue t3 = DAG.getNode(ISD::UINT_TO_FP, MVT::f32, t2);
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SDValue t4 = DAG.getNode(ISD::OR, MVT::i32, operand1,
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DAG.getConstant(1065353216, MVT::i32));
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SDValue t5 = DAG.getNode(ISD::AND, MVT::i32, t4,
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DAG.getConstant(1073741823, MVT::i32));
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SDValue t6 = DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t5);
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SDValue t7 = DAG.getNode(ISD::FMUL, MVT::f32, t6,
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DAG.getConstantFP(APFloat(
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APInt(32, 0xbda7262e)), MVT::f32));
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SDValue t8 = DAG.getNode(ISD::FADD, MVT::f32, t7,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f25280b)), MVT::f32));
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SDValue t9 = DAG.getNode(ISD::FMUL, MVT::f32, t8, t6);
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SDValue t10 = DAG.getNode(ISD::FSUB, MVT::f32, t9,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x4007b923)), MVT::f32));
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SDValue t11 = DAG.getNode(ISD::FMUL, MVT::f32, t10, t6);
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SDValue t12 = DAG.getNode(ISD::FADD, MVT::f32, t11,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40823e2f)), MVT::f32));
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SDValue t13 = DAG.getNode(ISD::FMUL, MVT::f32, t12, t6);
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SDValue t14 = DAG.getNode(ISD::FSUB, MVT::f32, t13,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x4020d29c)), MVT::f32));
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result = DAG.getNode(ISD::FADD, MVT::f32, t3, t14);
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DAG.getConstant(127, MVT::i32));
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SDValue LogOfExponent = DAG.getNode(ISD::UINT_TO_FP, MVT::f32, t2);
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// Get the significand and build it into a floating-point number with
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// exponent of 1:
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//
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// Op1 = (Op1 & 0x007fffff) | 0x3f800000;
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//
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// where Op1 is the hexidecimal representation of floating point value.
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SDValue t4 = DAG.getNode(ISD::AND, MVT::i32, Op1,
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DAG.getConstant(0x007fffff, MVT::i32));
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SDValue t5 = DAG.getNode(ISD::OR, MVT::i32, t4,
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DAG.getConstant(0x3f800000, MVT::i32));
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SDValue X = DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t5);
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// Different possible minimax approximations of significand in
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// floating-point for various degrees of accuracy over [1,2].
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if (LimitFloatPrecision <= 6) {
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// For floating-point precision of 6:
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//
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// Log2ofMantissa = -1.6749035f + (2.0246817f - .34484768f * x) * x;
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//
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// error 0.0049451742, which is more than 7 bits
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SDValue t8 = DAG.getNode(ISD::FMUL, MVT::f32, X,
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DAG.getConstantFP(APFloat(
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APInt(32, 0xbeb08fe0)), MVT::f32));
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SDValue t9 = DAG.getNode(ISD::FADD, MVT::f32, t8,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40019463)), MVT::f32));
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SDValue t10 = DAG.getNode(ISD::FMUL, MVT::f32, t9, X);
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SDValue Log2ofMantissa = DAG.getNode(ISD::FSUB, MVT::f32, t10,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3fd6633d)), MVT::f32));
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result = DAG.getNode(ISD::FADD, MVT::f32, LogOfExponent, Log2ofMantissa);
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} else if (LimitFloatPrecision > 6 && LimitFloatPrecision <= 12) {
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// For floating-point precision of 12:
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//
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// Log2ofMantissa =
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// -2.51285454f +
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// (4.07009056f +
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// (-2.12067489f +
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// (.645142248f - 0.816157886e-1f * x) * x) * x) * x;
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//
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// error 0.0000876136000, which is better than 13 bits
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SDValue t8 = DAG.getNode(ISD::FMUL, MVT::f32, X,
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DAG.getConstantFP(APFloat(
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APInt(32, 0xbda7262e)), MVT::f32));
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SDValue t9 = DAG.getNode(ISD::FADD, MVT::f32, t8,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f25280b)), MVT::f32));
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SDValue t10 = DAG.getNode(ISD::FMUL, MVT::f32, t9, X);
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SDValue t11 = DAG.getNode(ISD::FSUB, MVT::f32, t10,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x4007b923)), MVT::f32));
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SDValue t12 = DAG.getNode(ISD::FMUL, MVT::f32, t11, X);
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SDValue t13 = DAG.getNode(ISD::FADD, MVT::f32, t12,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40823e2f)), MVT::f32));
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SDValue t14 = DAG.getNode(ISD::FMUL, MVT::f32, t13, X);
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SDValue Log2ofMantissa = DAG.getNode(ISD::FSUB, MVT::f32, t14,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x4020d29c)), MVT::f32));
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result = DAG.getNode(ISD::FADD, MVT::f32, LogOfExponent, Log2ofMantissa);
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} else { // LimitFloatPrecision > 12 && LimitFloatPrecision <= 18
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// For floating-point precision of 18:
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//
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// Log2ofMantissa =
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// -3.0400495f +
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// (6.1129976f +
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// (-5.3420409f +
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// (3.2865683f +
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// (-1.2669343f +
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// (0.27515199f -
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// 0.25691327e-1f * x) * x) * x) * x) * x) * x;
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//
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// error 0.0000018516, which is better than 18 bits
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SDValue t8 = DAG.getNode(ISD::FMUL, MVT::f32, X,
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DAG.getConstantFP(APFloat(
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APInt(32, 0xbcd2769e)), MVT::f32));
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SDValue t9 = DAG.getNode(ISD::FADD, MVT::f32, t8,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3e8ce0b9)), MVT::f32));
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SDValue t10 = DAG.getNode(ISD::FMUL, MVT::f32, t9, X);
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SDValue t11 = DAG.getNode(ISD::FSUB, MVT::f32, t10,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3fa22ae7)), MVT::f32));
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SDValue t12 = DAG.getNode(ISD::FMUL, MVT::f32, t11, X);
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SDValue t13 = DAG.getNode(ISD::FADD, MVT::f32, t12,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40525723)), MVT::f32));
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SDValue t14 = DAG.getNode(ISD::FMUL, MVT::f32, t13, X);
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SDValue t15 = DAG.getNode(ISD::FSUB, MVT::f32, t14,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40aaf200)), MVT::f32));
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SDValue t16 = DAG.getNode(ISD::FMUL, MVT::f32, t15, X);
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SDValue t17 = DAG.getNode(ISD::FADD, MVT::f32, t16,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x40c39dad)), MVT::f32));
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SDValue t18 = DAG.getNode(ISD::FMUL, MVT::f32, t17, X);
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SDValue Log2ofMantissa = DAG.getNode(ISD::FSUB, MVT::f32, t18,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x4042902c)), MVT::f32));
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result = DAG.getNode(ISD::FADD, MVT::f32, LogOfExponent, Log2ofMantissa);
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}
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} else {
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// No special expansion.
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// No special expansion.
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result = DAG.getNode(ISD::FLOG2,
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getValue(I.getOperand(1)).getValueType(),
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getValue(I.getOperand(1)));
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}
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setValue(&I, result);
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}
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/// visitLog10 - lower a log10 intrinsic. Handles the special sequences
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/// for limited-precision mode.
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/// visitLog10 - Lower a log10 intrinsic. Handles the special sequences for
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/// limited-precision mode.
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void
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SelectionDAGLowering::visitLog10(CallInst &I) {
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SDValue result;
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if (getValue(I.getOperand(1)).getValueType() == MVT::f32 &&
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LimitFloatPrecision>0 && LimitFloatPrecision<=12) {
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SDValue operand = getValue(I.getOperand(1));
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SDValue operand1 = DAG.getNode(ISD::BIT_CONVERT, MVT::i32, operand);
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SDValue t0 = DAG.getNode(ISD::SRL, MVT::i32, operand1,
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DAG.getConstant(23, MVT::i32));
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SDValue t1 = DAG.getNode(ISD::AND, MVT::i32, t0,
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DAG.getConstant(255, MVT::i32));
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LimitFloatPrecision > 0 && LimitFloatPrecision <= 18) {
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SDValue Op = getValue(I.getOperand(1));
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SDValue Op1 = DAG.getNode(ISD::BIT_CONVERT, MVT::i32, Op);
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// Get the exponent, which is most of log10 and scale by log10(2).
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//
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// #define LOG10OF2 0.30102999f
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// Log10ofExponent = (float)(((Op1 & 0x7f800000) >> 23) - 127) * LOG10OF2;
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//
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// where Op1 is the hexidecimal value of the floating-point number.
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SDValue t0 = DAG.getNode(ISD::AND, MVT::i32, Op1,
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DAG.getConstant(0x7f800000, MVT::i32));
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SDValue t1 = DAG.getNode(ISD::SRL, MVT::i32, t0,
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DAG.getConstant(23, MVT::i32));
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SDValue t2 = DAG.getNode(ISD::SUB, MVT::i32, t1,
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DAG.getConstant(127, MVT::i32));
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DAG.getConstant(127, MVT::i32));
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SDValue t3 = DAG.getNode(ISD::UINT_TO_FP, MVT::f32, t2);
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SDValue t4 = DAG.getNode(ISD::FMUL, MVT::f32, t3,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3e9a209a)), MVT::f32));
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SDValue t5 = DAG.getNode(ISD::OR, MVT::i32, operand1,
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DAG.getConstant(1065353216, MVT::i32));
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SDValue t6 = DAG.getNode(ISD::AND, MVT::i32, t5,
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DAG.getConstant(1073741823, MVT::i32));
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SDValue t7 = DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t6);
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SDValue t8 = DAG.getNode(ISD::FMUL, MVT::f32, t7,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3d431f31)), MVT::f32));
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SDValue t9 = DAG.getNode(ISD::FSUB, MVT::f32, t8,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3ea21fb2)), MVT::f32));
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SDValue t10 = DAG.getNode(ISD::FMUL, MVT::f32, t9, t7);
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SDValue t11 = DAG.getNode(ISD::FADD, MVT::f32, t10,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f6ae232)), MVT::f32));
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SDValue t12 = DAG.getNode(ISD::FMUL, MVT::f32, t11, t7);
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SDValue t13 = DAG.getNode(ISD::FSUB, MVT::f32, t12,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f25f7c3)), MVT::f32));
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result = DAG.getNode(ISD::FADD, MVT::f32, t4, t13);
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SDValue LogOfExponent = DAG.getNode(ISD::FMUL, MVT::f32, t3,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3e9a209a)), MVT::f32));
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// Get the significand and build it into a floating-point number with
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// exponent of 1:
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//
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// Op1 = (Op1 & 0x007fffff) | 0x3f800000;
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//
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// where Op1 is the hexidecimal representation of floating point value.
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SDValue t4 = DAG.getNode(ISD::AND, MVT::i32, Op1,
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DAG.getConstant(0x007fffff, MVT::i32));
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SDValue t5 = DAG.getNode(ISD::OR, MVT::i32, t4,
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DAG.getConstant(0x3f800000, MVT::i32));
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SDValue X = DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t5);
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if (LimitFloatPrecision <= 6) {
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} else if (LimitFloatPrecision > 6 && LimitFloatPrecision <= 12) {
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// For floating-point precision of 12:
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//
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// Log10ofMantissa =
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// -0.64831180f +
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// (0.91751397f +
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// (-0.31664806f + 0.47637168e-1f * x) * x) * x;
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//
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// error 0.00019228036, which is better than 12 bits
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SDValue t6 = DAG.getNode(ISD::FMUL, MVT::f32, X,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3d431f31)), MVT::f32));
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SDValue t7 = DAG.getNode(ISD::FSUB, MVT::f32, t6,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3ea21fb2)), MVT::f32));
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SDValue t8 = DAG.getNode(ISD::FMUL, MVT::f32, t7, X);
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SDValue t9 = DAG.getNode(ISD::FADD, MVT::f32, t8,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f6ae232)), MVT::f32));
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SDValue t10 = DAG.getNode(ISD::FMUL, MVT::f32, t9, X);
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SDValue t11 = DAG.getNode(ISD::FSUB, MVT::f32, t10,
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DAG.getConstantFP(APFloat(
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APInt(32, 0x3f25f7c3)), MVT::f32));
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SDValue Log10ofMantissa = DAG.getNode(ISD::FP_ROUND, MVT::f32, t11,
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DAG.getConstant(0, MVT::i32));
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result = DAG.getNode(ISD::FADD, MVT::f32, LogOfExponent, Log10ofMantissa);
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} else { // LimitFloatPrecision > 12 && LimitFloatPrecision <= 18
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}
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} else {
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// No special expansion.
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// No special expansion.
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result = DAG.getNode(ISD::FLOG10,
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getValue(I.getOperand(1)).getValueType(),
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getValue(I.getOperand(1)));
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}
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setValue(&I, result);
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}
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/// visitExp2 - lower an exp2 intrinsic. Handles the special sequences
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/// for limited-precision mode.
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void
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SelectionDAGLowering::visitExp2(CallInst &I) {
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SDValue result;
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@ -2910,7 +3025,7 @@ SelectionDAGLowering::visitExp2(CallInst &I) {
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SDValue t11 = DAG.getNode(ISD::ADD, MVT::i32, t10, t3);
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result = DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t11);
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} else {
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// No special expansion.
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// No special expansion.
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result = DAG.getNode(ISD::FEXP2,
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getValue(I.getOperand(1)).getValueType(),
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getValue(I.getOperand(1)));
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