[PowerPC] Fix printing of negative offsets in call instruction dissasembly.

[sfertile]

ping

[hfinkel]

LGTM

lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp

extern "C" void LLVMInitializePowerPCDisassembler() {
   TargetRegistry::RegisterMCDisassembler(getThePPC32Target(),
                                          createPPCDisassembler);
   TargetRegistry::RegisterMCDisassembler(getThePPC64Target(),
                                          createPPCDisassembler);
   TargetRegistry::RegisterMCDisassembler(getThePPC64LETarget(),
                                          createPPCLEDisassembler);
 }
 
+static DecodeStatus DecodePCRel24BranchTarget(MCInst &Inst, unsigned Imm,
+                                              uint64_t Addr,
+                                              const void *Decoder) {
+  int32_t Offset = SignExtend32<24>(Imm);
+  Inst.addOperand(MCOperand::createImm(Offset));
+  return MCDisassembler::Success;
+}
+
 // FIXME: These can be generated by TableGen from the existing register
 // encoding values!
 
 template <std::size_t N>
 static DecodeStatus decodeRegisterClass(MCInst &Inst, uint64_t RegNo,
                                         const MCPhysReg (&Regs)[N]) {
   assert(RegNo < N && "Invalid register number");
   Inst.addOperand(MCOperand::createReg(Regs[RegNo]));

lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp

 
 void PPCInstPrinter::printBranchOperand(const MCInst *MI, unsigned OpNo,
                                         raw_ostream &O) {
   if (!MI->getOperand(OpNo).isImm())
     return printOperand(MI, OpNo, O);
 
   // Branches can take an immediate operand.  This is used by the branch
   // selection pass to print .+8, an eight byte displacement from the PC.
-  O << ".+";
-  printAbsBranchOperand(MI, OpNo, O);
+  O << ".";
+  int32_t Imm = MI->getOperand(OpNo).getImm() << 2;
+  if (Imm >= 0)
+    O << "+";
+  O << Imm;
 }
 
 void PPCInstPrinter::printAbsBranchOperand(const MCInst *MI, unsigned OpNo,
                                            raw_ostream &O) {
   if (!MI->getOperand(OpNo).isImm())
     return printOperand(MI, OpNo, O);
 
   O << SignExtend32<32>((unsigned)MI->getOperand(OpNo).getImm() << 2);

lib/Target/PowerPC/PPCInstrInfo.td

 def abscondbrtarget : Operand<OtherVT> {
   let PrintMethod = "printAbsBranchOperand";
   let EncoderMethod = "getAbsCondBrEncoding";
   let ParserMatchClass = PPCCondBrAsmOperand;
 }
 def calltarget : Operand<iPTR> {
   let PrintMethod = "printBranchOperand";
   let EncoderMethod = "getDirectBrEncoding";
+  let DecoderMethod = "DecodePCRel24BranchTarget";
   let ParserMatchClass = PPCDirectBrAsmOperand;
+  let OperandType = "OPERAND_PCREL";
 }
 def abscalltarget : Operand<iPTR> {
   let PrintMethod = "printAbsBranchOperand";
   let EncoderMethod = "getAbsDirectBrEncoding";
   let ParserMatchClass = PPCDirectBrAsmOperand;
 }
 def PPCCRBitMaskOperand : AsmOperandClass {
  let Name = "CRBitMask"; let PredicateMethod = "isCRBitMask";

test/tools/llvm-objdump/PowerPC/branch-offset.s

+# RUN: llvm-mc -triple=powerpc64le-unknown-linux -filetype=obj %s -o %t.o
+# RUN: llvm-objdump -d %t.o | FileCheck %s
+
+# RUN: llvm-mc -triple=powerpc64-unknown-linux -filetype=obj %s -o %t.o
+# RUN: llvm-objdump -d %t.o | FileCheck %s
+
+# RUN: llvm-mc -triple=powerpc-unknown-linux -filetype=obj %s -o %t.o
+# RUN: llvm-objdump -d %t.o | FileCheck %s
+
+# CHECK: 0000000000000000 callee_back:
+# CHECK: 18: {{.*}} bl .-24
+# CHECK: 20: {{.*}} bl .+16
+# CHECK: 0000000000000030 callee_forward:
+
+        .text
+        .global caller
+        .type caller,@function
+        .type callee_forward,@function
+        .type callee_back,@function
+
+        .p2align 4
+callee_back:
+        li 3, 55
+        blr
+
+        .p2align 4
+caller:
+.Lgep:
+        addis 2, 12, .TOC.-.Lgep@ha
+        addi 2, 2, .TOC.-.Lgep@l
+.Llep:
+        .localentry caller, .Llep-.Lgep
+        bl callee_back
+        mr 31, 3
+        bl callee_forward
+        add 3, 3, 31
+        blr
+
+        .p2align 4
+callee_forward:
+        li 3, 66
+        blr
+

test/tools/llvm-objdump/PowerPC/lit.local.cfg

+if not 'PowerPC' in config.root.targets:
+      config.unsupported = True