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Finished instruction replacement section, etc. Need better example for replaceAllUsesWith().

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3806 91177308-0d34-0410-b5e6-96231b3b80d8
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Joel Stanley 2002-09-18 03:17:23 +00:00
parent e6fe6713da
commit 9dd1ad62ab
1 changed files with 51 additions and 10 deletions
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@ -669,8 +669,7 @@ pb->getInstList().insert(pi, newInst); // inserts newInst before pi in pb
</p>
<li>Insertion into an implicit instruction list
<p>
<tt>Instruction</tt> instances that are already in
<p><tt>Instruction</tt> instances that are already in
<tt>BasicBlock</tt>s are implicitly associated with an existing
instruction list: the instruction list of the enclosing basic block.
Thus, we could have accomplished the same thing as the above code
@ -695,7 +694,7 @@ Instruction* newInst = new Instruction(..., pi);
</pre>
which is much cleaner, especially if you're creating a lot of
instructions and adding them to <tt>BasicBlock</tt>s.
</p>
</p>
</p>
</ul>
@ -718,17 +717,59 @@ For example:<p>
BB->getInstList().erase(I);
</pre><p>
<!--_______________________________________________________________________-->
</ul><h4><a name="schanges_replacing"><hr size=0>Replacing an
<tt>Instruction</tt> with another <tt>Value</tt></h4><ul>
<!-- Value::replaceAllUsesWith
User::replaceUsesOfWith
Point out: include/llvm/Transforms/Utils/
especially BasicBlockUtils.h with:
ReplaceInstWithValue, ReplaceInstWithInst
<p><i>Replacing individual instructions</i></p>
<p>
Including "<a
href="/doxygen/BasicBlock_8h-source.html">llvm/Transforms/Utils/BasicBlock.h
</a>" permits use of two very useful replace functions:
<tt>ReplaceInstWithValue</tt> and <tt>ReplaceInstWithInst</tt>.
<ul>
<li>ReplaceInstWithValue
<p>This function replaces all uses (within a basic block) of a given
instruction with a value, and then removes the original instruction.
The following example illustrates the replacement of the result of a
particular <tt>AllocaInst</tt> that allocates memory for a single
integer with an null pointer to an integer.</p>
<pre>
AllocaInst* instToReplace = ...;
ReplaceInstWithValue(*instToReplace->getParent(), instToReplace,
Constant::getNullValue(PointerType::get(Type::IntTy)));
</pre>
<li>ReplaceInstWithInst
<p>This function replaces a particular instruction with another
instruction. The following example illustrates the replacement of one
<tt>AllocaInst</tt> with another.<p>
<pre>
AllocaInst* instToReplace = ...;
ReplaceInstWithInst(*instToReplace->getParent(), instToReplace,
new AllocaInst(Type::IntTy, 0, "ptrToReplacedInt");
</pre>
</ul>
<p><i>Replacing multiple uses of <tt>User</tt>s and
<tt>Value</tt>s</i></p>
You can use <tt>Value::replaceAllUsesWith</tt> and
<tt>User::replaceUsesOfWith</tt> to change more than one use at a
time. See the doxygen documentation for the <a
href="/doxygen/classValue.html">Value Class</a> and <a
href="/doxygen/classUser.html">User Class</a>, respectively, for more
information.
<!-- Value::replaceAllUsesWith User::replaceUsesOfWith Point out:
include/llvm/Transforms/Utils/ especially BasicBlockUtils.h with:
ReplaceInstWithValue, ReplaceInstWithInst
-->
<!-- *********************************************************************** -->
@ -1575,6 +1616,6 @@ pointer to the parent Function.
<a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
<!-- hhmts start -->
Last modified: Tue Sep 17 17:41:54 CDT 2002
Last modified: Tue Sep 17 22:16:24 CDT 2002
<!-- hhmts end -->
</font></body></html>