[PowerPC] Support asm parsing for bc[l][a][+-] mnemonics

PowerPC assembly code in the wild, so it seems, has things like this:

  bc+     12, 28, .L9

This is a bit odd because the '+' here becomes part of the BO field, and the BO
field is otherwise the first operand. Nevertheless, the ISA specification does
clearly say that the +- hint syntax applies to all conditional-branch mnemonics
(that test either CTR or a condition register, although not the forms which
check both), both basic and extended, so this is supposed to be valid.

This introduces some asm-parser-only definitions which take only the upper
three bits from the specified BO value, and the lower two bits are implied by
the +- suffix (via some associated aliases).

Fixes PR23646.

llvm-svn: 280571

2 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp b/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
index d1c4b59e559..61ad5705329 100644
--- a/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
+++ b/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
@@ -258,6 +258,15 @@ void PPCInstPrinter::printPredicateOperand(const MCInst *MI, unsigned OpNo,
   printOperand(MI, OpNo+1, O);
 }
 
+void PPCInstPrinter::printATBitsAsHint(const MCInst *MI, unsigned OpNo,
+                                       raw_ostream &O) {
+  unsigned Code = MI->getOperand(OpNo).getImm();
+  if (Code == 2)
+    O << "-";
+  else if (Code == 3)
+    O << "+";
+}
+
 void PPCInstPrinter::printU1ImmOperand(const MCInst *MI, unsigned OpNo,
                                        raw_ostream &O) {
   unsigned int Value = MI->getOperand(OpNo).getImm();
diff --git a/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.h b/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.h
index d0ffeff0247..9c79ffb1176 100644
--- a/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.h
+++ b/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.h
@@ -45,6 +45,7 @@ public:
   void printOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
   void printPredicateOperand(const MCInst *MI, unsigned OpNo,
                              raw_ostream &O, const char *Modifier = nullptr);
+  void printATBitsAsHint(const MCInst *MI, unsigned OpNo, raw_ostream &O);
 
   void printU1ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
   void printU2ImmOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);