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Draft fix for a series of multiplications (#75413) #76941

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Draft fix for a series of multiplications (#75413) #76941

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18 changes: 18 additions & 0 deletions src/coreclr/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12687,6 +12687,24 @@ GenTree* Compiler::fgOptimizeMultiply(GenTreeOp* mul)
fgUpdateConstTreeValueNumber(op2);
mul->ChangeOper(GT_LSH, GenTree::PRESERVE_VN);

if (mul->gtGetOp1()->OperIs(GT_LSH) && mul->gtGetOp1()->gtGetOp2()->IsIntegralConst())
{
GenTree* lsOp = mul->gtGetOp1();
GenTree* rsOp = mul->gtGetOp2();
GenTree* lsOpChOp1 = lsOp->gtGetOp1();
GenTree* lsOpChOp2 = lsOp->gtGetOp2();

int64_t child_val = lsOpChOp2->AsIntConCommon()->IntegralValue();
int64_t root_val = rsOp->AsIntConCommon()->IntegralValue();

mul->gtOp1 = lsOpChOp1;
mul->gtOp2 = lsOpChOp2;
mul->gtOp2->AsIntConCommon()->SetIntegralValue(root_val + child_val);

DEBUG_DESTROY_NODE(lsOp);
DEBUG_DESTROY_NODE(rsOp);
}

return mul;
}
}
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