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take care of some todos, transforming [us]mul_lohi into

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a wider mul if the wider mul is legal.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121848 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-12-15 06:04:19 +00:00
parent 2ff28e4b9e
commit 33e77d3cb9
2 changed files with 47 additions and 2 deletions
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48
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -2045,7 +2045,29 @@ SDValue DAGCombiner::visitSMUL_LOHI(SDNode *N) {
SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHS);
if (Res.getNode()) return Res;
// TODO: Transform smul_lohi to mul if the wider mul is legal!
EVT VT = N->getValueType(0);
DebugLoc DL = N->getDebugLoc();
// If the type twice as wide is legal, transform the mulhu to a wider multiply
// plus a shift.
if (VT.isSimple() && !VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
SDValue Lo = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(0));
SDValue Hi = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(1));
Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
// Compute the high part as N1.
Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
DAG.getConstant(SimpleSize, getShiftAmountTy()));
Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
// Compute the low part as N0.
Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
return CombineTo(N, Lo, Hi);
}
}
return SDValue();
}
@ -2053,7 +2075,29 @@ SDValue DAGCombiner::visitUMUL_LOHI(SDNode *N) {
SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHU);
if (Res.getNode()) return Res;
// TODO: Transform umul_lohi to mul if the wider mul is legal!
EVT VT = N->getValueType(0);
DebugLoc DL = N->getDebugLoc();
// If the type twice as wide is legal, transform the mulhu to a wider multiply
// plus a shift.
if (VT.isSimple() && !VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
SDValue Lo = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(0));
SDValue Hi = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(1));
Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
// Compute the high part as N1.
Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
DAG.getConstant(SimpleSize, getShiftAmountTy()));
Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
// Compute the low part as N0.
Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
return CombineTo(N, Lo, Hi);
}
}
return SDValue();
}

1
test/CodeGen/X86/divide-by-constant.ll
View File

@ -40,6 +40,7 @@ entry:
%div = sdiv i16 %x, 33 ; <i32> [#uses=1]
ret i16 %div
; CHECK: test4:
; CHECK: imull $-1985, %ecx, %ecx
}
define i32 @test5(i32 %A) nounwind {