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Add dag combine to simplify lmul(x, 0, a, b) 

llvm-svn: 98258
This commit is contained in:
Richard Osborne 2010-03-11 16:26:35 +00:00
parent dd819c981f
commit 4780109254
2 changed files with 40 additions and 0 deletions
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27
llvm/lib/Target/XCore/XCoreISelLowering.cpp
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@ -1345,6 +1345,33 @@ SDValue XCoreTargetLowering::PerformDAGCombine(SDNode *N,
}
}
break;
case XCoreISD::LMUL: {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
SDValue N3 = N->getOperand(3);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
EVT VT = N0.getValueType();
// Canonicalize multiplicative constant to RHS. If both multiplicative
// operands are constant canonicalize smallest to RHS.
if ((N0C && !N1C) ||
(N0C && N1C && N0C->getZExtValue() < N1C->getZExtValue()))
return DAG.getNode(XCoreISD::LMUL, dl, DAG.getVTList(VT, VT), N1, N0, N2, N3);
// lmul(x, 0, a, b)
if (N1C && N1C->isNullValue()) {
// If the high result is unused fold to add(a, b)
if (N->hasNUsesOfValue(0, 0)) {
SDValue Lo = DAG.getNode(ISD::ADD, dl, VT, N2, N3);
SDValue Ops [] = { Lo, Lo };
return DAG.getMergeValues(Ops, 2, dl);
}
// Otherwise fold to ladd(a, b, 0)
return DAG.getNode(XCoreISD::LADD, dl, DAG.getVTList(VT, VT), N2, N3, N1);
}
}
break;
case ISD::ADD: {
// Fold 32 bit expressions such as add(add(mul(x,y),a),b) ->
// lmul(x, y, a, b). The high result of lmul will be ignored.

13
llvm/test/CodeGen/XCore/mul64.ll
View File

@ -37,3 +37,16 @@ entry:
; CHECK-NEXT: mul r0, r0, r3
; CHECK-NEXT: lmul r0, r1, r1, r2, r11, r0
; CHECK-NEXT: mov r0, r4
define i64 @mul64_2(i64 %a, i32 %b) {
entry:
%0 = zext i32 %b to i64
%1 = mul i64 %a, %0
ret i64 %1
}
; CHECK: mul64_2:
; CHECK: ldc r3, 0
; CHECK-NEXT: lmul r3, r0, r0, r2, r3, r3
; CHECK-NEXT: mul r1, r1, r2
; CHECK-NEXT: add r1, r3, r1
; CHECK-NEXT: retsp 0