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Differential D112316

[LangRef] Document that DataLayout defaults to little-endian
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Authored by frasercrmck on Oct 22 2021, 7:38 AM.

Details

Reviewers
chandlerc
dblaikie
fhahn
nikic
Commits
rGc3dce37a55e1: [LangRef] Document that DataLayout defaults to little-endian
Summary

Little-endian has apparently been the default since 2014.

Diff Detail

Event Timeline

frasercrmck created this revision.Oct 22 2021, 7:38 AM
Herald added a subscriber: jdoerfert. · View Herald TranscriptOct 22 2021, 7:38 AM
frasercrmck requested review of this revision.Oct 22 2021, 7:38 AM
Herald added a project: Restricted Project. · View Herald TranscriptOct 22 2021, 7:38 AM
Herald added a subscriber: llvm-commits. · View Herald Transcript
Harbormaster completed remote builds in B130140: Diff 381545.Oct 22 2021, 7:42 AM
xgupta added reviewers: dblaikie, fhahn.Oct 23 2021, 2:43 AM
frasercrmck mentioned this in D112463: [LangRef] Remove incorrect vector alignment rules.Oct 25 2021, 9:12 AM
nikic accepted this revision.Oct 25 2021, 9:22 AM
nikic added a subscriber: nikic.

LGTM

This revision is now accepted and ready to land.Oct 25 2021, 9:22 AM
frasercrmck retitled this revision from [LangRef][NFC] Document that DataLayout defaults to little-endian to [LangRef] Document that DataLayout defaults to little-endian.Oct 25 2021, 9:30 AM
frasercrmck updated this revision to Diff 382233.Oct 26 2021, 2:22 AM
  • rebase
Harbormaster completed remote builds in B130639: Diff 382233.Oct 26 2021, 2:55 AM
Closed by commit rGc3dce37a55e1: [LangRef] Document that DataLayout defaults to little-endian (authored by frasercrmck). · Explain WhyOct 26 2021, 3:03 AM
This revision was automatically updated to reflect the committed changes.
frasercrmck added a commit: rGc3dce37a55e1: [LangRef] Document that DataLayout defaults to little-endian.

Revision Contents

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docs/
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llvm/docs/LangRef.rst

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``<pref>`` alignment is optional. If omitted, the preceding ``:`` ``<pref>`` alignment is optional. If omitted, the preceding ``:``
should be omitted too and ``<pref>`` will be equal to ``<abi>``. should be omitted too and ``<pref>`` will be equal to ``<abi>``.
When constructing the data layout for a given target, LLVM starts with a When constructing the data layout for a given target, LLVM starts with a
default set of specifications which are then (possibly) overridden by default set of specifications which are then (possibly) overridden by
the specifications in the ``datalayout`` keyword. The default the specifications in the ``datalayout`` keyword. The default
specifications are given in this list: specifications are given in this list:
- ``E`` - big endian - ``e`` - little endian
- ``p:64:64:64`` - 64-bit pointers with 64-bit alignment. - ``p:64:64:64`` - 64-bit pointers with 64-bit alignment.
- ``p[n]:64:64:64`` - Other address spaces are assumed to be the - ``p[n]:64:64:64`` - Other address spaces are assumed to be the
same as the default address space. same as the default address space.
- ``S0`` - natural stack alignment is unspecified - ``S0`` - natural stack alignment is unspecified
- ``i1:8:8`` - i1 is 8-bit (byte) aligned - ``i1:8:8`` - i1 is 8-bit (byte) aligned
- ``i8:8:8`` - i8 is 8-bit (byte) aligned - ``i8:8:8`` - i8 is 8-bit (byte) aligned
- ``i16:16:16`` - i16 is 16-bit aligned - ``i16:16:16`` - i16 is 16-bit aligned
- ``i32:32:32`` - i32 is 32-bit aligned - ``i32:32:32`` - i32 is 32-bit aligned
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