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Use "SINT_TO_FP" instead of "UINT_TO_FP" when getting the exponent. This was

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causing the limited precision stuff to produce the wrong result for values in
the range [0, 1).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62615 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2009-01-20 21:17:57 +00:00
parent 2be5893a04
commit e9a7286087
1 changed files with 13 additions and 12 deletions
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25
lib/CodeGen/SelectionDAG/SelectionDAGBuild.cpp
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@ -2945,26 +2945,27 @@ void AddCatchInfo(CallInst &I, MachineModuleInfo *MMI,
/// where Op is the hexidecimal representation of floating point value.
static SDValue
GetSignificand(SelectionDAG &DAG, SDValue Op) {
SDValue t1 = DAG.getNode(ISD::AND, MVT::i32, Op,
DAG.getConstant(0x007fffff, MVT::i32));
SDValue t2 = DAG.getNode(ISD::OR, MVT::i32, t1,
DAG.getConstant(0x3f800000, MVT::i32));
return DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t2);
SDValue t1 = DAG.getNode(ISD::AND, MVT::i32, Op,
DAG.getConstant(0x007fffff, MVT::i32));
SDValue t2 = DAG.getNode(ISD::OR, MVT::i32, t1,
DAG.getConstant(0x3f800000, MVT::i32));
return DAG.getNode(ISD::BIT_CONVERT, MVT::f32, t2);
}
/// GetExponent - Get the exponent:
///
/// (float)((Op1 >> 23) - 127);
/// (float)(int)(((Op & 0x7f800000) >> 23) - 127);
///
/// where Op is the hexidecimal representation of floating point value.
static SDValue
GetExponent(SelectionDAG &DAG, SDValue Op, const TargetLowering &TLI) {
SDValue t1 = DAG.getNode(ISD::SRL, MVT::i32, Op,
DAG.getConstant(23, TLI.getShiftAmountTy()));
SDValue t2 = DAG.getNode(ISD::SUB, MVT::i32, t1,
DAG.getConstant(127, MVT::i32));
// SDValue t3 = DAG.getNode(ISD::BIT_CONVERT, MVT::i32, t2);
return DAG.getNode(ISD::UINT_TO_FP, MVT::f32, t2);
SDValue t0 = DAG.getNode(ISD::AND, MVT::i32, Op,
DAG.getConstant(0x7f800000, MVT::i32));
SDValue t1 = DAG.getNode(ISD::SRL, MVT::i32, t0,
DAG.getConstant(23, TLI.getShiftAmountTy()));
SDValue t2 = DAG.getNode(ISD::SUB, MVT::i32, t1,
DAG.getConstant(127, MVT::i32));
return DAG.getNode(ISD::SINT_TO_FP, MVT::f32, t2);
}
/// getF32Constant - Get 32-bit floating point constant.