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Don't forget to diddle with the control word when performing an FISTP64.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22550 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-07-29 00:54:34 +00:00
parent 745d538119
commit f7443dace5
1 changed files with 36 additions and 8 deletions
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44
lib/Target/X86/X86ISelPattern.cpp
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@ -54,11 +54,12 @@ namespace {
/// address) and two outputs (FP value and token chain).
FILD64m,
/// FISTP64m - This instruction implements FP_TO_SINT with a
/// 64-bit destination in memory and a FP reg source. This corresponds to
/// the X86::FISTP64m instruction. It has two inputs (token chain and
/// address) and two outputs (FP value and token chain).
FISTP64m,
/// FP_TO_INT*_IN_MEM - This instruction implements FP_TO_SINT with the
/// integer destination in memory and a FP reg source. This corresponds
/// to the X86::FIST*m instructions and the rounding mode change stuff. It
/// has two inputs (token chain and address) and two outputs (FP value and
/// token chain).
FP_TO_INT64_IN_MEM,
/// CALL/TAILCALL - These operations represent an abstract X86 call
/// instruction, which includes a bunch of information. In particular the
@ -988,10 +989,10 @@ SDOperand X86TargetLowering::LowerOperation(SDOperand Op, SelectionDAG &DAG) {
Ops.push_back(DAG.getEntryNode());
Ops.push_back(Op.getOperand(0));
Ops.push_back(StackSlot);
SDOperand FISTP = DAG.getNode(X86ISD::FISTP64m, MVT::Other, Ops);
SDOperand FIST = DAG.getNode(X86ISD::FP_TO_INT64_IN_MEM, MVT::Other, Ops);
// Load the result.
return DAG.getLoad(MVT::i64, FISTP, StackSlot, DAG.getSrcValue(NULL));
return DAG.getLoad(MVT::i64, FIST, StackSlot, DAG.getSrcValue(NULL));
}
}
}
@ -4356,7 +4357,7 @@ void ISel::Select(SDOperand N) {
SelectExpr(N.getValue(0));
return;
case X86ISD::FISTP64m: {
case X86ISD::FP_TO_INT64_IN_MEM: {
assert(N.getOperand(1).getValueType() == MVT::f64);
X86AddressMode AM;
Select(N.getOperand(0)); // Select the token chain
@ -4369,7 +4370,34 @@ void ISel::Select(SDOperand N) {
SelectAddress(N.getOperand(2), AM);
ValReg = SelectExpr(N.getOperand(1));
}
// Change the floating point control register to use "round towards zero"
// mode when truncating to an integer value.
//
MachineFunction *F = BB->getParent();
int CWFrameIdx = F->getFrameInfo()->CreateStackObject(2, 2);
addFrameReference(BuildMI(BB, X86::FNSTCW16m, 4), CWFrameIdx);
// Load the old value of the high byte of the control word...
unsigned HighPartOfCW = MakeReg(MVT::i8);
addFrameReference(BuildMI(BB, X86::MOV8rm, 4, HighPartOfCW),
CWFrameIdx, 1);
// Set the high part to be round to zero...
addFrameReference(BuildMI(BB, X86::MOV8mi, 5),
CWFrameIdx, 1).addImm(12);
// Reload the modified control word now...
addFrameReference(BuildMI(BB, X86::FLDCW16m, 4), CWFrameIdx);
// Restore the memory image of control word to original value
addFrameReference(BuildMI(BB, X86::MOV8mr, 5),
CWFrameIdx, 1).addReg(HighPartOfCW);
addFullAddress(BuildMI(BB, X86::FISTP64m, 5), AM).addReg(ValReg);
// Reload the original control word now.
addFrameReference(BuildMI(BB, X86::FLDCW16m, 4), CWFrameIdx);
return;
}