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<title>Extending LLVM: Adding instructions, intrinsics, types, etc.</title>
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support for it. Generally you must do the following steps:</p>
<dl>
-<dt>Add support to the C backend in <tt>lib/Target/CBackend/</tt></dt>
-
-<dd>Depending on the intrinsic, there are a few ways to implement this. For
- most intrinsics, it makes sense to add code to lower your intrinsic in
- <tt>LowerIntrinsicCall</tt> in <tt>lib/CodeGen/IntrinsicLowering.cpp</tt>.
- Second, if it makes sense to lower the intrinsic to an expanded sequence of
- C code in all cases, just emit the expansion in <tt>visitCallInst</tt> in
- <tt>Writer.cpp</tt>. If the intrinsic has some way to express it with GCC
- (or any other compiler) extensions, it can be conditionally supported based
- on the compiler compiling the CBE output (see <tt>llvm.prefetch</tt> for an
- example). Third, if the intrinsic really has no way to be lowered, just
- have the code generator emit code that prints an error message and calls
- abort if executed.</dd>
<dt>Add support to the .td file for the target(s) of your choice in
<tt>lib/Target/*/*.td</tt>.</dt>
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