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Diffstat (limited to 'docs/WritingAnLLVMBackend.html')
| -rw-r--r-- | docs/WritingAnLLVMBackend.html | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/docs/WritingAnLLVMBackend.html b/docs/WritingAnLLVMBackend.html index 11517c212401..b7fdce490472 100644 --- a/docs/WritingAnLLVMBackend.html +++ b/docs/WritingAnLLVMBackend.html @@ -32,6 +32,7 @@ <li><a href="#InstructionSet">Instruction Set</a> <ul> <li><a href="#operandMapping">Instruction Operand Mapping</a></li> + <li><a href="#relationMapping">Instruction Relation Mapping</a></li> <li><a href="#implementInstr">Implement a subclass of TargetInstrInfo</a></li> <li><a href="#branchFolding">Branch Folding and If Conversion</a></li> </ul></li> @@ -314,14 +315,14 @@ represent target components. These methods are named <tt>get*Info</tt>, and are intended to obtain the instruction set (<tt>getInstrInfo</tt>), register set (<tt>getRegisterInfo</tt>), stack frame layout (<tt>getFrameInfo</tt>), and similar information. <tt>XXXTargetMachine</tt> must also implement the -<tt>getTargetData</tt> method to access an object with target-specific data +<tt>getDataLayout</tt> method to access an object with target-specific data characteristics, such as data type size and alignment requirements. </p> <p> For instance, for the SPARC target, the header file <tt>SparcTargetMachine.h</tt> declares prototypes for several <tt>get*Info</tt> -and <tt>getTargetData</tt> methods that simply return a class member. +and <tt>getDataLayout</tt> methods that simply return a class member. </p> <div class="doc_code"> @@ -331,7 +332,7 @@ namespace llvm { class Module; class SparcTargetMachine : public LLVMTargetMachine { - const TargetData DataLayout; // Calculates type size & alignment + const DataLayout DataLayout; // Calculates type size & alignment SparcSubtarget Subtarget; SparcInstrInfo InstrInfo; TargetFrameInfo FrameInfo; @@ -348,7 +349,7 @@ public: virtual const TargetRegisterInfo *getRegisterInfo() const { return &InstrInfo.getRegisterInfo(); } - virtual const TargetData *getTargetData() const { return &DataLayout; } + virtual const DataLayout *getDataLayout() const { return &DataLayout; } static unsigned getModuleMatchQuality(const Module &M); // Pass Pipeline Configuration @@ -364,7 +365,7 @@ public: <li><tt>getInstrInfo()</tt></li> <li><tt>getRegisterInfo()</tt></li> <li><tt>getFrameInfo()</tt></li> -<li><tt>getTargetData()</tt></li> +<li><tt>getDataLayout()</tt></li> <li><tt>getSubtargetImpl()</tt></li> </ul> @@ -1259,6 +1260,29 @@ the <tt>rd</tt>, <tt>rs1</tt>, and <tt>rs2</tt> fields respectively. <!-- ======================================================================= --> <h3> + <a name="relationMapping">Instruction Relation Mapping</a> +</h3> + +<div> + +<p> +This TableGen feature is used to relate instructions with each other. It is +particularly useful when you have multiple instruction formats and need to +switch between them after instruction selection. This entire feature is driven +by relation models which can be defined in <tt>XXXInstrInfo.td</tt> files +according to the target-specific instruction set. Relation models are defined +using <tt>InstrMapping</tt> class as a base. TableGen parses all the models +and generates instruction relation maps using the specified information. +Relation maps are emitted as tables in the <tt>XXXGenInstrInfo.inc</tt> file +along with the functions to query them. For the detailed information on how to +use this feature, please refer to +<a href="HowToUseInstrMappings.html">How to add Instruction Mappings</a> +document. +</p> +</div> + +<!-- ======================================================================= --> +<h3> <a name="implementInstr">Implement a subclass of </a> <a href="CodeGenerator.html#targetinstrinfo">TargetInstrInfo</a> </h3> @@ -2526,7 +2550,7 @@ with assembler. <a href="http://www.woo.com">Mason Woo</a> and <a href="http://misha.brukman.net">Misha Brukman</a><br> <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a> <br> - Last modified: $Date: 2012-04-19 22:20:34 +0200 (Thu, 19 Apr 2012) $ + Last modified: $Date: 2012-10-25 17:54:06 +0200 (Thu, 25 Oct 2012) $ </address> </body> |