+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.
+ ++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: +
+ +
+Target llvm::TheSparcTarget;
+
+extern "C" void LLVMInitializeSparcTargetInfo() {
+ RegisterTarget<Triple::sparc, /*HasJIT=*/false>
+ X(TheSparcTarget, "sparc", "Sparc");
+}
+
+-You must also register your target using the RegisterTarget -template. (See the TargetMachineRegistry class.) For example, -in SparcTargetMachine.cpp, the target is registered with: +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:
-namespace {
- // Register the target.
- RegisterTarget<SparcTargetMachine>X("sparc", "SPARC");
+extern "C" void LLVMInitializeSparcAsmPrinter() {
+ RegisterAsmPrinter<SparcAsmPrinter> X(TheSparcTarget);
}
+For more information, see +"llvm/Target/TargetRegistry.h". +
+This defines the register AL and assigns it values (with DwarfRegNum) that are used by gcc, gdb, or a debug -information writer (such as DwarfWriter -in llvm/lib/CodeGen/AsmPrinter) to identify a register. For register +information writer to identify a register. For register AL, DwarfRegNum takes an array of 3 values representing 3 different modes: the first element is for X86-64, the second for exception handling (EH) on X86-32, and the third is generic. -1 is a special Dwarf number @@ -874,9 +913,6 @@ implementation in SparcRegisterInfo.cpp:
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.
@@ -2110,21 +2146,13 @@ 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.