Add a PrintRegUnit helper similar to PrintReg.

Reg-units are named after their root registers, and most units have a
single root, so they simply print as 'AL', 'XMM0', etc. The rare dual
root reg-units print as FPSCR~FPSCR_NZCV, FP0~ST7, ...

The printing piggybacks on the existing register name tables, so no
extra const data space is required.

llvm-svn: 157754

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/Target/TargetRegisterInfo.cpp b/llvm/lib/Target/TargetRegisterInfo.cpp
index a989cf4a7af..2395f2ba12a 100644
--- a/llvm/lib/Target/TargetRegisterInfo.cpp
+++ b/llvm/lib/Target/TargetRegisterInfo.cpp
@@ -46,6 +46,27 @@ void PrintReg::print(raw_ostream &OS) const {
   }
 }
 
+void PrintRegUnit::print(raw_ostream &OS) const {
+  // Generic printout when TRI is missing.
+  if (!TRI) {
+    OS << "Unit~" << Unit;
+    return;
+  }
+
+  // Check for invalid register units.
+  if (Unit >= TRI->getNumRegUnits()) {
+    OS << "BadUnit~" << Unit;
+    return;
+  }
+
+  // Normal units have at least one root.
+  MCRegUnitRootIterator Roots(Unit, TRI);
+  assert(Roots.isValid() && "Unit has no roots.");
+  OS << TRI->getName(*Roots);
+  for (++Roots; Roots.isValid(); ++Roots)
+    OS << '~' << TRI->getName(*Roots);
+}
+
 /// getAllocatableClass - Return the maximal subclass of the given register
 /// class that is alloctable, or NULL.
 const TargetRegisterClass *