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| author | Sean Silva <silvas@purdue.edu> | 2013-05-20 23:31:12 +0000 |
|---|---|---|
| committer | Sean Silva <silvas@purdue.edu> | 2013-05-20 23:31:12 +0000 |
| commit | 57f429fcac5d3ade255611fd663b35101e3eb228 (patch) | |
| tree | 4dba889bc5ffcace453d6a7a29d0eda7ccd50726 /docs | |
| parent | 7b72cc7782716f469eb1b0963423a5b414215705 (diff) | |
| download | llvm-57f429fcac5d3ade255611fd663b35101e3eb228.tar.gz llvm-57f429fcac5d3ade255611fd663b35101e3eb228.tar.bz2 llvm-57f429fcac5d3ade255611fd663b35101e3eb228.tar.xz | |
LangRef.rst: Clarify how basic blocks without named label are handled.
Describe that they are assigned numbered label using the same counter
as for unnamed temporaries.
Based on http://llvm.org/bugs/show_bug.cgi?id=16043 and mailing list
discussion.
Patch by Paul Sokolovsky!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182332 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/LangRef.rst | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/docs/LangRef.rst b/docs/LangRef.rst index 4d006f135c..4eecd15a6f 100644 --- a/docs/LangRef.rst +++ b/docs/LangRef.rst @@ -127,7 +127,8 @@ lexical features of LLVM: #. Comments are delimited with a '``;``' and go until the end of line. #. Unnamed temporaries are created when the result of a computation is not assigned to a named value. -#. Unnamed temporaries are numbered sequentially +#. Unnamed temporaries are numbered sequentially (using a per-function + incrementing counter, starting with 0). It also shows a convention that we follow in this document. When demonstrating instructions, we will follow an instruction with a comment @@ -563,7 +564,11 @@ A function definition contains a list of basic blocks, forming the CFG start with a label (giving the basic block a symbol table entry), contains a list of instructions, and ends with a :ref:`terminator <terminators>` instruction (such as a branch or function -return). +return). If explicit label is not provided, a block is assigned an +implicit numbered label, using a next value from the same counter as used +for unnamed temporaries (:ref:`see above<identifiers>`). For example, if a +function entry block does not have explicit label, it will be assigned +label "%0", then first unnamed temporary in that block will be "%1", etc. The first basic block in a function is special in two ways: it is immediately executed on entrance to the function, and it is not allowed |