diff options
Diffstat (limited to 'docs/BitCodeFormat.rst')
| -rw-r--r-- | docs/BitCodeFormat.rst | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/docs/BitCodeFormat.rst b/docs/BitCodeFormat.rst index 429c945e7120..5e1c5cacb439 100644 --- a/docs/BitCodeFormat.rst +++ b/docs/BitCodeFormat.rst @@ -62,10 +62,12 @@ understanding the encoding. Magic Numbers ------------- -The first two bytes of a bitcode file are 'BC' (``0x42``, ``0x43``). The second -two bytes are an application-specific magic number. Generic bitcode tools can -look at only the first two bytes to verify the file is bitcode, while -application-specific programs will want to look at all four. +The first four bytes of a bitstream are used as an application-specific magic +number. Generic bitcode tools may look at the first four bytes to determine +whether the stream is a known stream type. However, these tools should *not* +determine whether a bitstream is valid based on its magic number alone. New +application-specific bitstream formats are being developed all the time; tools +should not reject them just because they have a hitherto unseen magic number. .. _primitives: @@ -496,12 +498,9 @@ LLVM IR Magic Number The magic number for LLVM IR files is: :raw-html:`<tt><blockquote>` -[0x0\ :sub:`4`, 0xC\ :sub:`4`, 0xE\ :sub:`4`, 0xD\ :sub:`4`] +['B'\ :sub:`8`, 'C'\ :sub:`8`, 0x0\ :sub:`4`, 0xC\ :sub:`4`, 0xE\ :sub:`4`, 0xD\ :sub:`4`] :raw-html:`</blockquote></tt>` -When combined with the bitcode magic number and viewed as bytes, this is -``"BC 0xC0DE"``. - .. _Signed VBRs: Signed VBRs @@ -904,7 +903,7 @@ PARAMATTR_CODE_ENTRY Record The ``ENTRY`` record (code 2) contains a variable number of values describing a unique set of function parameter attributes. Each *attrgrp* value is used as a -key with which to look up an entry in the the attribute group table described +key with which to look up an entry in the attribute group table described in the ``PARAMATTR_GROUP_BLOCK`` block. .. _PARAMATTR_CODE_ENTRY_OLD: @@ -1055,6 +1054,9 @@ The integer codes are mapped to well-known attributes as follows. * code 53: ``speculatable`` * code 54: ``strictfp`` * code 55: ``sanitize_hwaddress`` +* code 56: ``nocf_check`` +* code 57: ``optforfuzzing`` +* code 58: ``shadowcallstack`` .. note:: The ``allocsize`` attribute has a special encoding for its arguments. Its two |