Avoid unaligned stores/loads #584
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The result of `Data_custom_Val(caml_alloc_custom(...))` is word aligned. `long double` and `long double complex` are usually bigger. Such usage is even wrong on x86/amd64. Compilers are free to use e.g. the MOVDQA instruction, if you tell them that your pointers are properly aligned.
yallop
reviewed
Dec 6, 2018
| mymemcpy(&c, p, sizeof(c)); | ||
| #else | ||
| memcpy(&c, p, sizeof(c)); | ||
| #endif |
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Could we ask the Alpine people to compile using -fno-builtin instead of fixing the GCC problem here?
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Alpine is used by various CIs, including the ones by https://github.com/ocaml/opam-repository. A solution that isn't enabled by default would lead to frustration. I could move the check to the build system and add -fno-builtin there, but it would probably lead to even more lines of code.
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Okay. Since the fix is constrained to a specific GCC release, it should at least be clear when we can safely remove it.
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The result of
Data_custom_Val(caml_alloc_custom(...))is wordaligned.
long doubleandlong double complexare usuallybigger. Such usage is even wrong on x86/amd64. Compilers are free to
use e.g. the MOVDQA instruction, if you tell them that your pointers are
properly aligned.