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| author | David Young <dyoung@hdfgroup.org> | 2022-04-16 15:21:18 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2022-04-16 15:21:18 (GMT) |
| commit | a80897ee4944ff6008bfb3b93619ebcb58a070d1 (patch) | |
| tree | f01b999aa5168e6869e4cf35c073377e3db09cd7 /configure.ac | |
| parent | 463ef39bc777340b731903995a2ad416ec5e0ae4 (diff) | |
| download | hdf5-a80897ee4944ff6008bfb3b93619ebcb58a070d1.zip hdf5-a80897ee4944ff6008bfb3b93619ebcb58a070d1.tar.gz hdf5-a80897ee4944ff6008bfb3b93619ebcb58a070d1.tar.bz2 | |
Remove H5_NO_ALIGNMENT_RESTRICTIONS (#1426)
* Do not conditionally compile code that uses a pointer dereference
and assignment to copy a potentially unaligned variable to aligned
automatic storage, or vice versa. Instead, always use naked `memcpy(3)`s.
Disassembling the generated code reveals that the `memcpy(3)`s optimize
(`-O3`) to a single `mov` instruction for x86_64, which is not strict
about alignment.
This change reduces the size of code and scripts by 143 lines, eases
our way to cross-compilation, and avoids invoking undefined behavior.
* Committing clang-format changes
* Per discussion, use HD and add comments.
Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 19 |
1 files changed, 0 insertions, 19 deletions
diff --git a/configure.ac b/configure.ac index d5cef35..908ece7 100644 --- a/configure.ac +++ b/configure.ac @@ -3990,25 +3990,6 @@ AC_ARG_ENABLE([embedded-libinfo], ## ---------------------------------------------------------------------- -## Check if pointer alignments are enforced -## -AC_MSG_CHECKING([if alignment restrictions are strictly enforced]) - -TEST_SRC="`(echo \"#define H5_NO_ALIGNMENT_RESTRICTIONS_TEST 1\"; cat $srcdir/config/cmake/ConversionTests.c)`" - -AC_RUN_IFELSE([ - AC_LANG_SOURCE([$TEST_SRC]) - ], [ - AC_DEFINE([NO_ALIGNMENT_RESTRICTIONS], [1], [Define if we can violate pointer alignment restrictions]) - AC_MSG_RESULT([no]) - ], [ - AC_MSG_RESULT([yes]) - ], [ - AC_MSG_RESULT([unknown, assuming yes]) - ]) - - -## ---------------------------------------------------------------------- ## Restore user's CFLAGS. CFLAGS="$saved_user_CFLAGS" FCFLAGS="$saved_user_FCFLAGS" |