[llvm-dev] returning from LowerOperation()

Matt Arsenault via llvm-dev llvm-dev at lists.llvm.org
Mon Jan 23 12:41:18 PST 2017

> On Jan 23, 2017, at 12:36, Friedman, Eli via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> On 1/23/2017 5:21 AM, Jonas Paulsson wrote:
>> Hi Eli,
>> I would like to clarify generally what the difference is between returning SDValue() and Op (input argument unchanged) from LowerOperation()?
>> My understanding is that returning SDValue() means that Target gives up, and the common code is supposed to handle it. Returning Op, the unchanged argument, means that the Target is happy with the node as it is, and the common code can move on to something else.
> This is right.

This sounds backwards. Returning SDValue() means the node should be treated as legal. Returning the original operation should hit the expand path.

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