# Can't have more than one constant operand to an SALU compare

**URL:** <https://forum.p4.org/t/cant-have-more-than-one-constant-operand-to-an-salu-compare/511>\
**Category:** Getting Started with P4\
**Created:** [November 2, 2022, 9:26am UTC](https://forum.p4.org/t/cant-have-more-than-one-constant-operand-to-an-salu-compare/511 "2022-11-02T09:26:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![KathyJXY](https://avatars.discourse-cdn.com/v4/letter/k/7cd45c/32.png) [@KathyJXY](https://forum.p4.org/u/KathyJXY)\
**Post date:** [November 2, 2022, 9:26am UTC](https://forum.p4.org/t/cant-have-more-than-one-constant-operand-to-an-salu-compare/511/1 "2022-11-02T09:26:55Z")

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When I compiling my p4 program on tna, I got the error message:  
error: can’t have more than one constant operand to an SALU compare.

I have no clue of what’s causing this error, can anyone give some advice please?  
Thanks in advance.

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**Author:** ![vgurevich](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.p4.org/vgurevich/32/23_2.png) [@vgurevich](https://forum.p4.org/u/vgurevich)\
**Post date:** [November 2, 2022, 2:33pm UTC](https://forum.p4.org/t/cant-have-more-than-one-constant-operand-to-an-salu-compare/511/2 "2022-11-02T14:33:02Z")

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Hello Kathy,

Welcome to the forum! You can find a lot of useful information here, especially if you use it search function. For example, [a simple search on the “tna” and “SALU” keywords](https://forum.p4.org/search?q=tna%20salu) will immediately produce [this post](https://forum.p4.org/t/tofino-tna-and-p4studio-questions/504), that contains the necessary recommendations.

Happy hacking,  
Vladimir