pkg/micro-ecc: fix on GCC 15.2.0 for AVR #21920
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maribu
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Type: bug
This was referenced Nov 29, 2025
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- add a work around for a (presumably) compiler bug in GCC 15.2.0 register allocation code by manually a function argument into the Y register. - add missing `"memory"` clobber to inline asm implementations. With GCC 15.2.0 the `vli_mmod_fast_secp256r1()` function would not compute correctly without the `"memory"` clobber.
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benpicco
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Nov 30, 2025
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Contribution description
vli_mmod_fast_secp256r1()Testing procedure
will fail to build without the first patch (0002-...patch) added, and will fail in the test without the second patch (0003-...patch) added when compiled with GCC 15.2.0.
Issues/PRs references
vli_mmod_fast_secp256r1()computes incorrect result on AVR with GCC 15.2.0 kmackay/micro-ecc#236