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Fold add(add(mul(x,y),a),b) -> lmul(x,y,a,b) if the intermediate

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results are unused elsewhere.

llvm-svn: 98157
This commit is contained in:
Richard Osborne 2010-03-10 16:19:31 +00:00
parent adf47face1
commit d400202a43
2 changed files with 68 additions and 0 deletions
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56
lib/Target/XCore/XCoreISelLowering.cpp
View File

@ -154,6 +154,7 @@ XCoreTargetLowering::XCoreTargetLowering(XCoreTargetMachine &XTM)
// We have target-specific dag combine patterns for the following nodes:
setTargetDAGCombine(ISD::STORE);
setTargetDAGCombine(ISD::ADD);
}
SDValue XCoreTargetLowering::
@ -1279,6 +1280,61 @@ SDValue XCoreTargetLowering::PerformDAGCombine(SDNode *N,
}
}
break;
case ISD::ADD: {
// Fold expressions such as add(add(mul(x,y),a),b) -> lmul(x, y, a, b).
// This is only profitable if the intermediate results are unused
// elsewhere.
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue AddOp;
SDValue OtherOp;
if (N0.getOpcode() == ISD::ADD) {
AddOp = N0;
OtherOp = N1;
} else if (N1.getOpcode() == ISD::ADD) {
AddOp = N1;
OtherOp = N0;
} else {
break;
}
SDValue Addend0, Addend1;
SDValue Mul0;
SDValue Mul1;
if (OtherOp.getOpcode() == ISD::MUL) {
// add(add(a,b),mul(x,y))
if (!OtherOp.hasOneUse() || !AddOp.hasOneUse())
break;
Mul0 = OtherOp.getOperand(0);
Mul1 = OtherOp.getOperand(1);
Addend0 = AddOp.getOperand(0);
Addend1 = AddOp.getOperand(1);
} else if (AddOp.getOperand(0).getOpcode() == ISD::MUL) {
// add(add(mul(x,y),a),b)
if (!AddOp.getOperand(0).hasOneUse())
break;
Mul0 = AddOp.getOperand(0).getOperand(0);
Mul1 = AddOp.getOperand(0).getOperand(1);
Addend0 = AddOp.getOperand(1);
Addend1 = OtherOp;
} else if (AddOp.getOperand(1).getOpcode() == ISD::MUL) {
// add(add(a,mul(x,y)),b)
if (!AddOp.getOperand(1).hasOneUse())
break;
Mul0 = AddOp.getOperand(1).getOperand(0);
Mul1 = AddOp.getOperand(1).getOperand(1);
Addend0 = AddOp.getOperand(0);
Addend1 = OtherOp;
} else {
break;
}
SDValue Zero = DAG.getConstant(0, MVT::i32);
SDValue Ignored = DAG.getNode(XCoreISD::LMUL, dl,
DAG.getVTList(MVT::i32, MVT::i32), Mul0,
Mul1, Addend0, Addend1);
SDValue Result(Ignored.getNode(), 1);
return Result;
}
break;
case ISD::STORE: {
// Replace unaligned store of unaligned load with memmove.
StoreSDNode *ST = cast<StoreSDNode>(N);

12
test/CodeGen/XCore/mul64.ll
View File

@ -25,3 +25,15 @@ entry:
; CHECK-NEXT: mov r0, r3
; CHECK-NEXT: mov r1, r2
; CHECK-NEXT: retsp 0
define i64 @mul64(i64 %a, i64 %b) {
entry:
%0 = mul i64 %a, %b
ret i64 %0
}
; CHECK: mul64:
; CHECK: ldc r11, 0
; CHECK-NEXT: lmul r11, r4, r0, r2, r11, r11
; CHECK-NEXT: mul r0, r0, r3
; CHECK-NEXT: lmul r0, r1, r1, r2, r11, r0
; CHECK-NEXT: mov r0, r4