6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-08-05 13:26:55 +00:00
Code Issues Projects Releases Wiki Activity

Implement (and document!) support for MnemonicAlias's to have Requires

Browse Source 
directives, allowing things like this:

def : MnemonicAlias<"pop", "popl">, Requires<[In32BitMode]>;
def : MnemonicAlias<"pop", "popq">, Requires<[In64BitMode]>;

Move the rest of the X86 MnemonicAliases over to the .td file.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117830 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-10-30 19:23:13 +00:00
parent 8cc0a6b788
commit 693173feef
5 changed files with 108 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
docs/CodeGenerator.html
View File

@@ -1896,7 +1896,7 @@ compiler.</p>
The MatchInstructionImpl function performs alias processing and then does
actual matching.</p>
<p>Alias processing if the phase that canonicalizes different lexical forms of
<p>Alias processing is 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
@@ -1911,7 +1911,7 @@ description.</p>
<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
mnemonics. 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:
@@ -1928,7 +1928,19 @@ def : MnemonicAlias&lt;"ud2a", "ud2"&gt;;
</div>
<p>... and many others. With a MnemonicAlias definition, the mnemonic is
remapped simply and directly.</p>
remapped simply and directly. Though MnemonicAlias's can't look at any aspect
of the instruction (such as the operands) they can depend on global modes (the
same ones supported by the matcher), through a Requires clause:</p>
<div class="doc_code">
<pre>
def : MnemonicAlias&lt;"pushf", "pushfq"&gt;, Requires&lt;[In64BitMode]&gt;;
def : MnemonicAlias&lt;"pushf", "pushfl"&gt;, Requires&lt;[In32BitMode]&gt;;
</pre>
</div>
<p>In this example, the mnemonic gets mapped into different a new one depending
on the current instruction set.</p>
</div>