[globalisel][tablegen] Add support for COPY_TO_REGCLASS.

Summary:
As part of this
* Emitted instructions now have named MachineInstr variables associated
  with them. This isn't particularly important yet but it's a small step
  towards multiple-insn emission.
* constrainSelectedInstRegOperands() is no longer hardcoded. It's now added
  as the ConstrainOperandsToDefinitionAction() action. COPY_TO_REGCLASS uses
  an alternate constraint mechanism ConstrainOperandToRegClassAction() which
  supports arbitrary constraints such as that defined by COPY_TO_REGCLASS.

Reviewers: ab, qcolombet, t.p.northover, rovka, kristof.beyls, aditya_nandakumar

Reviewed By: ab

Subscribers: javed.absar, igorb, llvm-commits

Differential Revision: https://reviews.llvm.org/D33590

llvm-svn: 305791

1 files changed, 18 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/Utils.cpp b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
index 254bdf10d80..5ecaf5c563f 100644
--- a/llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -26,6 +26,23 @@
 
 using namespace llvm;
 
+unsigned llvm::constrainRegToClass(MachineRegisterInfo &MRI,
+                                   const TargetInstrInfo &TII,
+                                   const RegisterBankInfo &RBI,
+                                   MachineInstr &InsertPt, unsigned Reg,
+                                   const TargetRegisterClass &RegClass) {
+  if (!RBI.constrainGenericRegister(Reg, RegClass, MRI)) {
+    unsigned NewReg = MRI.createVirtualRegister(&RegClass);
+    BuildMI(*InsertPt.getParent(), InsertPt, InsertPt.getDebugLoc(),
+            TII.get(TargetOpcode::COPY), NewReg)
+        .addReg(Reg);
+    return NewReg;
+  }
+
+  return Reg;
+}
+
+
 unsigned llvm::constrainOperandRegClass(
     const MachineFunction &MF, const TargetRegisterInfo &TRI,
     MachineRegisterInfo &MRI, const TargetInstrInfo &TII,
@@ -36,16 +53,7 @@ unsigned llvm::constrainOperandRegClass(
          "PhysReg not implemented");
 
   const TargetRegisterClass *RegClass = TII.getRegClass(II, OpIdx, &TRI, MF);
-
-  if (!RBI.constrainGenericRegister(Reg, *RegClass, MRI)) {
-    unsigned NewReg = MRI.createVirtualRegister(RegClass);
-    BuildMI(*InsertPt.getParent(), InsertPt, InsertPt.getDebugLoc(),
-            TII.get(TargetOpcode::COPY), NewReg)
-        .addReg(Reg);
-    return NewReg;
-  }
-
-  return Reg;
+  return constrainRegToClass(MRI, TII, RBI, InsertPt, Reg, *RegClass);
 }
 
 bool llvm::isTriviallyDead(const MachineInstr &MI,