[PATCH] D45991: GlobalISel: Use a callback to compute constrained reg class for unallocatble registers

[Tom Stellard via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL331485: GlobalISel: Use a callback to compute constrained reg class for unallocatble… (authored by tstellar, committed by ).

Repository:
  rL LLVM

https://reviews.llvm.org/D45991

Files:
  llvm/trunk/include/llvm/CodeGen/TargetRegisterInfo.h
  llvm/trunk/lib/CodeGen/GlobalISel/Utils.cpp


Index: llvm/trunk/include/llvm/CodeGen/TargetRegisterInfo.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/TargetRegisterInfo.h
+++ llvm/trunk/include/llvm/CodeGen/TargetRegisterInfo.h
@@ -995,6 +995,12 @@
   /// of the set as well.
   bool checkAllSuperRegsMarked(const BitVector &RegisterSet,
       ArrayRef<MCPhysReg> Exceptions = ArrayRef<MCPhysReg>()) const;
+
+  virtual const TargetRegisterClass *
+  getConstrainedRegClassForOperand(const MachineOperand &MO,
+                                   const MachineRegisterInfo &MRI) const {
+    return nullptr;
+  }
 };
 
 //===----------------------------------------------------------------------===//
Index: llvm/trunk/lib/CodeGen/GlobalISel/Utils.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/Utils.cpp
+++ llvm/trunk/lib/CodeGen/GlobalISel/Utils.cpp
@@ -58,6 +58,13 @@
   // register class constraints on some of their operands: If it's a use, we can
   // skip constraining as the instruction defining the register would constrain
   // it.
+
+  // We can't constrain unallocatable register classes, because we can't create
+  // virtual registers for these classes, so we need to let targets handled this
+  // case.
+  if (RegClass && !RegClass->isAllocatable())
+    RegClass = TRI.getConstrainedRegClassForOperand(RegMO, MRI);
+
   if (!RegClass) {
     assert((!isTargetSpecificOpcode(II.getOpcode()) || RegMO.isUse()) &&
            "Register class constraint is required unless either the "


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