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Validation fixes 

llvm-svn: 42230
This commit is contained in:
Bill Wendling 2007-09-22 10:07:00 +00:00
parent bdd6bd8236
commit 31e1e5e37a
1 changed files with 11 additions and 12 deletions
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23
llvm/docs/ExtendingLLVM.html
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@ -107,19 +107,17 @@ support for it. Generally you must do the following steps:</p>
<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>
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>
<dl>
<dt>Add support to the .td file for the target(s) of your choice in
<tt>lib/Target/*/*.td</tt>.</dt>
@ -127,6 +125,7 @@ generator emit code that prints an error message and calls abort if executed.
the intrinsic, though it may obviously require adding the instructions you
want to generate as well. There are lots of examples in the PowerPC and X86
backend to follow.</dd>
</dl>
</div>