[PowerPC][AIX] Fix printing of program counter for AIX assembly.

[sfertile]

Summary

Program counter on AIX is the dollar-sign.

[hubert.reinterpretcast]

llvm/lib/Target/PowerPC/MCTargetDesc/PPCInstPrinter.cpp

422

Suggestion:

[ ... ] This is used by the branch selection pass to print, for example, `.+8` (for ELF) or `$+8` (on AIX) to express an eight byte displacement from the program counter.

llvm/test/CodeGen/PowerPC/aix-print-pc.mir

2

Is this a case where we can (or should) test for 64-bit now?

[sfertile]

Reworded comment and added 64-bit RUN step to the test.

[sfertile]

llvm/test/CodeGen/PowerPC/aix-print-pc.mir

2

Sure, we have enough 64-bit assembly support. I've added a 64-bit runstep.

[jasonliu]

LGTM.

[daltenty]

Noticed that what we get from MAI.getDollarIsPC() on AIX isn't consistent with this patch. We should probably update that property as well and emit consistently according to that if we can (note though PPC ELF currently sets it (?)).

llvm/lib/Target/PowerPC/MCTargetDesc/PPCInstPrinter.cpp

else
     printOperand(MI, OpNo, O);
 }
 
 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.
+  // Branches can take an immediate operand. This is used by the branch
+  // selection pass to print, for example `.+8` (for ELF) or `$+8` (for AIX) to
+  // express an eight byte displacement from the program counter.
+  if (!TT.isOSAIX())
     O << ".";
+  else
+    O << "$";
+
   int32_t Imm = SignExtend32<32>((unsigned)MI->getOperand(OpNo).getImm() << 2);
   if (Imm >= 0)
     O << "+";
   O << Imm;
 }
 
 void PPCInstPrinter::printAbsBranchOperand(const MCInst *MI, unsigned OpNo,
                                            raw_ostream &O) {

llvm/test/CodeGen/PowerPC/aix-print-pc.mir

+# RUN: llc -x mir -mtriple powerpc-unknown-aix-xcoff --verify-machineinstrs \
+# RUN: -start-before=ppc-branch-select < %s | FileCheck %s
+#
+# RUN: llc -x mir -mtriple powerpc64-unknown-aix-xcoff --verify-machineinstrs \
+# RUN: -start-before=ppc-branch-select < %s | FileCheck %s
+
+# Test uses a long branch to force printing of a branch that uses the program
+# counter as an operand. ($PC + 8)
+
+---
+name:            print_program_counter
+machineFunctionInfo: {}
+body:             |
+  bb.0.entry:
+    successors: %bb.1(0x30000000), %bb.2(0x50000000)
+    liveins: $r3
+    renamable $cr0 = CMPLWI killed renamable $r3, 0
+    BCC 76, killed renamable $cr0, %bb.1
+  bb.2:
+    renamable $r3 = LI 2
+    INLINEASM &".space 32760", 1
+    BLR implicit $lr, implicit $rm, implicit killed $r3
+  bb.1:
+    renamable $r3 = LI 1
+    INLINEASM &".space 32760", 1
+    BLR implicit $lr, implicit $rm, implicit killed $r3
+
+# CHECK-LABEL: .print_program_counter:
+# CHECK:         cmplwi
+# CHECK-NEXT:    bne    {{[0-9]}}, $+8
+