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authorDan Gohman <gohman@apple.com>2010-03-10 01:29:39 +0000
committerDan Gohman <gohman@apple.com>2010-03-10 01:29:39 +0000
commit9f116aa3b1ece85b863099ffa7ea1cab88ef46a8 (patch)
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Clarify the documentation for MachineFunctionPasses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98119 91177308-0d34-0410-b5e6-96231b3b80d8
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@@ -909,16 +909,22 @@ finalization.</p>
<p>A <tt>MachineFunctionPass</tt> is a part of the LLVM code generator that
executes on the machine-dependent representation of each LLVM function in the
-program. A <tt>MachineFunctionPass</tt> is also a <tt>FunctionPass</tt>, so all
+program.</p>
+
+<p>Code generator passes are registered and initialized specially by
+<tt>TargetMachine::addPassesToEmitFile</tt> and similar routines, so they
+cannot generally be run from the <tt>opt</tt> or <tt>bugpoint</tt>
+commands.</p>
+
+<p>A <tt>MachineFunctionPass</tt> is also a <tt>FunctionPass</tt>, so all
the restrictions that apply to a <tt>FunctionPass</tt> also apply to it.
<tt>MachineFunctionPass</tt>es also have additional restrictions. In particular,
<tt>MachineFunctionPass</tt>es are not allowed to do any of the following:</p>
<ol>
-<li>Modify any LLVM Instructions, BasicBlocks or Functions.</li>
+<li>Modify or create any LLVM IR Instructions, BasicBlocks, Arguments,
+ Functions, GlobalVariables, GlobalAliases, or Modules.</li>
<li>Modify a MachineFunction other than the one currently being processed.</li>
-<li>Add or remove MachineFunctions from the current Module.</li>
-<li>Add or remove global variables from the current Module.</li>
<li>Maintain state across invocations of <a
href="#runOnMachineFunction"><tt>runOnMachineFunction</tt></a> (including global
data)</li>