| Issue |
154125
|
| Summary |
[RISC-V] zero extension should be preferred over bit field extraction
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
christian-herber-nxp
|
I have seen code size expansion in two workloads of embench-iot 1.0 (edn and picojpeg), when using the t-head bitfield extension.
I could not isolate a trivial code snippet. For anything simple, zext.h is used.
This is one where you can see and instruction in the style of th.extu rd, rs, 15, 0 being used in favor of zext.h:
https://godbolt.org/z/beb4r4Kzq
This is suboptimal, as zext.h can possibly be compressed. Might not be the case, here, but it happens elsewhere and hurts code density.
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