Why does tablegen not provide the #undef keyword, how do I invalidate the defined macro in *.td file?

LLVM Project
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1

Problem Description

I want to include different parts of a file through different macro definitions in the td file, but I found that there is no #undef keyword, so I would like to ask tblgen if there are other mechanisms to achieve conditional inclusion.If #undef is not provided, how do I invalidate the defined macro? If you can answer, thank you very much!

Scenario example

fileA.td:

#define B_A
include "fileB.td"

#define B_B
include "fileB.td"

fileB.td:

#ifdef B_A
// Duplicate inclusion due to no #undef keyword
//#undef B_A
......
#endif

#ifdef B_B
// Duplicate inclusion due to no #undef keyword
......
#endif
2

I don’t think there is any specific reason other than there was no such a need. Feel free to send a patch to add that feature!

3

Thank you for your reply;
I found a small bug in tablegen, and I want to add the #undef macro keyword to it. I am studying how to submit code to llvm.

4

Alternatively, if it works for your case, you can change first block in fileB to the equivalent of #if defined(B_A) and not defined(B_B)

5

This is an idea, but if my file consists of four or more parts that are conditionally included, then I will have to define a large number of such code structures.
I have submitted the relevant undef code and it is still under review.