[ARM][Asm] Debug trace for the processInstruction loop

In the Arm assembly parser, we first match an instruction, then call
processInstruction to possibly change it to a different encoding, to
match rules in the architecture manual which can't be expressed by the
table-generated matcher.

This adds debug printing so that this process is visible when using the
-debug option.

To support this, I've added a new overload of MCInst::dump_pretty which
takes the opcode name as a StringRef, since we don't have an InstPrinter
instance in the assembly parser. Instead, we can get the same
information directly from the MCInstrInfo.

Differential revision: https://reviews.llvm.org/D54852

llvm-svn: 348113

1 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/MC/MCInst.cpp b/llvm/lib/MC/MCInst.cpp
index f9b71caaf91..64f111fc711 100644
--- a/llvm/lib/MC/MCInst.cpp
+++ b/llvm/lib/MC/MCInst.cpp
@@ -72,11 +72,17 @@ void MCInst::print(raw_ostream &OS) const {
 
 void MCInst::dump_pretty(raw_ostream &OS, const MCInstPrinter *Printer,
                          StringRef Separator) const {
+  StringRef InstName = Printer ? Printer->getOpcodeName(getOpcode()) : "";
+  dump_pretty(OS, InstName, Separator);
+}
+
+void MCInst::dump_pretty(raw_ostream &OS, StringRef Name,
+                         StringRef Separator) const {
   OS << "<MCInst #" << getOpcode();
 
-  // Show the instruction opcode name if we have access to a printer.
-  if (Printer)
-    OS << ' ' << Printer->getOpcodeName(getOpcode());
+  // Show the instruction opcode name if we have it.
+  if (!Name.empty())
+    OS << ' ' << Name;
 
   for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
     OS << Separator;