+You must also register your target with the TargetRegistry, which is +what other LLVM tools use to be able to lookup and use your target at +runtime. The TargetRegistry can be used directly, but for most targets +there are helper templates which should take care of the work for you.
+-You must also register your target using the RegisterTarget -template. (See the TargetMachineRegistry class.) For example, -in SparcTargetMachine.cpp, the target is registered with: +All targets should declare a global Target object which is used to +represent the target during registration. Then, in the target's TargetInfo +library, the target should define that object and use +the RegisterTarget template to register the target. For example, the Sparc registration code looks like this:
-namespace {
- // Register the target.
- RegisterTarget<SparcTargetMachine>X("sparc", "SPARC");
+Target llvm::TheSparcTarget;
+
+extern "C" void LLVMInitializeSparcTargetInfo() {
+ RegisterTarget<Triple::sparc, /*HasJIT=*/false>
+ X(TheSparcTarget, "sparc", "Sparc");
}
+This allows the TargetRegistry to look up the target by name or by +target triple. In addition, most targets will also register additional features +which are available in separate libraries. These registration steps are +separate, because some clients may wish to only link in some parts of the target +-- the JIT code generator does not require the use of the assembler printer, for +example. Here is an example of registering the Sparc assembly printer: +
+ +
+extern "C" void LLVMInitializeSparcAsmPrinter() {
+ RegisterAsmPrinter<SparcAsmPrinter> X(TheSparcTarget);
+}
+
++For more information, see +"llvm/Target/TargetRegistry.h". +
+The X86 assembly printer implementation (X86TargetAsmInfo) is an -example where the target specific TargetAsmInfo class uses overridden -methods: ExpandInlineAsm and PreferredEHDataFormat. +example where the target specific TargetAsmInfo class uses an +overridden methods: ExpandInlineAsm.
@@ -2109,21 +2150,13 @@ in XXXGenAsmWriter.inc contains an implementation of the
The implementations of printDeclare, printImplicitDef, printInlineAsm, and printLabel in AsmPrinter.cpp are generally adequate for printing assembly and do not need to be -overridden. (printBasicBlockLabel is another method that is implemented -in AsmPrinter.cpp that may be directly used in an implementation of -XXXAsmPrinter.) +overridden.