s390x-linux and general big-endian stuff#25965
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alexrp merged 24 commits intoziglang:masterfrom Nov 19, 2025
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Integers with padding bits on big-endian targets cannot quite be bitcast with a trivial memcpy, because the padding bits (which are zext or sext) are the most-significant, so are at the *lowest* addresses. So to bitcast to something which doesn't have padding bits, we need to offset past the padding. The logic I've added here definitely doesn't handle all possibilities correctly; I think that would actually be quite complicated. However, it handles a common case, and so prevents the Zig compiler itself from being miscompiled on big-endian targets (hence fixing a bootstrapping problem on big-endian).
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The big-endian logic here was simply incorrect. Luckily, it was also overcomplicated; after calling `Value.writeToPackedMemory`, there is a method on `std.math.big.int.Mutable` which just does the correct endianness load for us.
Signed-off-by: Alex Rønne Petersen <alex@alexrp.com>
Again, `std.zig.Server` expects little-endian. This is easy; we just use a `Reader.fixed` instead of directly `@ptrCast`ing data out of the buffer.
Little-endian is what `std.zig.Server` expects, but the old logic just send the raw bytes of the struct, so sent in native endian (causing a crash on big-endian targets).
…test This has no business being here. Tests for our compiler-rt routines should be in compiler-rt, and tests for our C ABI compliance should be in `test-c-abi`.
mlugg
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Nov 19, 2025
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