[llvm] r182332 - LangRef.rst: Clarify how basic blocks without named label are handled.

[Sean Silva]

Author: silvas
Date: Mon May 20 18:31:12 2013
New Revision: 182332

URL: http://llvm.org/viewvc/llvm-project?rev=182332&view=rev
Log:
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!

Modified:
    llvm/trunk/docs/LangRef.rst

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=182332&r1=182331&r2=182332&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Mon May 20 18:31:12 2013
@@ -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
 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