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Diffstat (limited to 'docs/CodeGenerator.html')
| -rw-r--r-- | docs/CodeGenerator.html | 55 |
1 files changed, 52 insertions, 3 deletions
diff --git a/docs/CodeGenerator.html b/docs/CodeGenerator.html index 3e0ac1b..de6a5c1 100644 --- a/docs/CodeGenerator.html +++ b/docs/CodeGenerator.html @@ -1878,15 +1878,64 @@ We've tried hard to automate the generation of the assembler from the .td files part of the manual and repetitive data entry can be factored and shared with the compiler.</p> +</div> +<!-- ======================================================================= --> +<div class="doc_subsection" id="na_instparsing">Instruction Parsing</div> -</div> +<div class="doc_text"><p>To Be Written</p></div> <!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="proepicode">Prolog/Epilog Code Insertion</a> +<div class="doc_subsection" id="na_instaliases"> + Instruction Alias Processing </div> + +<div class="doc_text"> +<p>Once the instruction is parsed, it enters the MatchInstructionImpl function. +The MatchInstructionImpl function performs alias processing and then does +actual matching.</p> + +<p>Alias processing if the phase that canonicalizes different lexical forms of +the same instructions down to one representation. There are several different +kinds of alias that are possible to implement and they are listed below in the +order that they are processed (which is in order from simplest/weakest to most +complex/powerful). Generally you want to use the first alias mechanism that +meets the needs of your instruction, because it will allow a more concise +description.</p> + +<!-- _______________________________________________________________________ --> +<div class="doc_subsubsection">Mnemonic Aliases</div> + +<div class="doc_text"> + +<p>The first phase of alias processing is simple instruction mneomonic +remapping for classes of instructions which are allowed with two different +mneomonics. This phase is a simple and unconditionally remapping from one input +mnemonic to one output mnemonic. It isn't possible for this form of alias to +look at the operands at all, so the remapping must apply for all forms of a +given mnemonic. Mnemonic aliases are defined simply, for example X86 has: +</p> + +<div class="doc_code"> +<pre> +def : MnemonicAlias<"cbw", "cbtw">; +def : MnemonicAlias<"smovq", "movsq">; +def : MnemonicAlias<"fldcww", "fldcw">; +def : MnemonicAlias<"fucompi", "fucomip">; +def : MnemonicAlias<"ud2a", "ud2">; +</pre> +</div> + +<p>... and many others. With a MnemonicAlias definition, the mnemonic is +remapped simply and directly.</p> + +</div> + + +<!-- ======================================================================= --> +<div class="doc_subsection" id="na_matching">Instruction Matching</div> + <div class="doc_text"><p>To Be Written</p></div> |