[llvm] r260558 - [GlobalISel] Add a type to MachineInstr.

[Quentin Colombet via llvm-commits]

> On Feb 11, 2016, at 10:22 AM, Quentin Colombet via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Author: qcolombet
> Date: Thu Feb 11 12:22:37 2016
> New Revision: 260558
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=260558&view=rev
> Log:
> [GlobalISel] Add a type to MachineInstr.
> We actually need that information only for generic instructions, therefore it
> would be nice not to have to pay the extra memory consumption for all
> instructions. Especially because a typed non-generic instruction does not make
> sense.
> 
> The question is then, is it possible to have that information in a union or
> something?
> My initial thought was that we could have a derived class GenericMachineInstr
> with additional information, but in practice it makes little to no sense since
> generic MachineInstrs are likely turned into non-generic ones by just switching
> the opcode. In other words, we don't want to go through the process of creating
> a new, non-generic MachineInstr, object each time we do this switch. The memory
> benefit probably is not worth the extra compile time.
> 
> Another option would be to keep the type of the MachineInstr in a side table.
> This would induce an extra indirection though.
> 
> Anyway, I will file a PR to discuss about it and remember we need to come back
> to it at some point.

This is https://llvm.org/bugs/show_bug.cgi?id=26576

> 
> Modified:
>    llvm/trunk/include/llvm/CodeGen/MachineInstr.h
>    llvm/trunk/lib/CodeGen/MachineInstr.cpp
> 
> Modified: llvm/trunk/include/llvm/CodeGen/MachineInstr.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineInstr.h?rev=260558&r1=260557&r2=260558&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/CodeGen/MachineInstr.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/MachineInstr.h Thu Feb 11 12:22:37 2016
> @@ -38,6 +38,9 @@ template <typename T> class SmallVectorI
> class TargetInstrInfo;
> class TargetRegisterClass;
> class TargetRegisterInfo;
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +class Type;
> +#endif
> class MachineFunction;
> class MachineMemOperand;
> 
> @@ -102,6 +105,13 @@ private:
> 
>   DebugLoc debugLoc;                    // Source line information.
> 
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +  /// Type of the instruction in case of a generic opcode.
> +  /// \invariant This must be nullptr is getOpcode() is not
> +  /// in the range of generic opcodes.
> +  Type *Ty;
> +#endif
> +
>   MachineInstr(const MachineInstr&) = delete;
>   void operator=(const MachineInstr&) = delete;
>   // Use MachineFunction::DeleteMachineInstr() instead.
> @@ -176,6 +186,19 @@ public:
>     Flags &= ~((uint8_t)Flag);
>   }
> 
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +  /// Set the type of the instruction.
> +  /// \pre getOpcode() is in the range of the generic opcodes.
> +  void setType(Type *Ty) {
> +    assert(
> +        (!Ty || (getOpcode() >= TargetOpcode::PRE_ISEL_GENERIC_OPCODE_START &&
> +                 getOpcode() <= TargetOpcode::PRE_ISEL_GENERIC_OPCODE_END)) &&
> +        "Non generic instructions are not supposed to be typed");
> +    this->Ty = Ty;
> +  }
> +  Type *getType() const { return Ty; }
> +#endif
> +
>   /// Return true if MI is in a bundle (but not the first MI in a bundle).
>   ///
>   /// A bundle looks like this before it's finalized:
> 
> Modified: llvm/trunk/lib/CodeGen/MachineInstr.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineInstr.cpp?rev=260558&r1=260557&r2=260558&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineInstr.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineInstr.cpp Thu Feb 11 12:22:37 2016
> @@ -653,7 +653,12 @@ MachineInstr::MachineInstr(MachineFuncti
>                            DebugLoc dl, bool NoImp)
>     : MCID(&tid), Parent(nullptr), Operands(nullptr), NumOperands(0), Flags(0),
>       AsmPrinterFlags(0), NumMemRefs(0), MemRefs(nullptr),
> -      debugLoc(std::move(dl)) {
> +      debugLoc(std::move(dl))
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +      ,
> +      Ty(nullptr)
> +#endif
> +{
>   assert(debugLoc.hasTrivialDestructor() && "Expected trivial destructor");
> 
>   // Reserve space for the expected number of operands.
> @@ -670,10 +675,14 @@ MachineInstr::MachineInstr(MachineFuncti
> /// MachineInstr ctor - Copies MachineInstr arg exactly
> ///
> MachineInstr::MachineInstr(MachineFunction &MF, const MachineInstr &MI)
> -  : MCID(&MI.getDesc()), Parent(nullptr), Operands(nullptr), NumOperands(0),
> -    Flags(0), AsmPrinterFlags(0),
> -    NumMemRefs(MI.NumMemRefs), MemRefs(MI.MemRefs),
> -    debugLoc(MI.getDebugLoc()) {
> +    : MCID(&MI.getDesc()), Parent(nullptr), Operands(nullptr), NumOperands(0),
> +      Flags(0), AsmPrinterFlags(0), NumMemRefs(MI.NumMemRefs),
> +      MemRefs(MI.MemRefs), debugLoc(MI.getDebugLoc())
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +      ,
> +      Ty(nullptr)
> +#endif
> +{
>   assert(debugLoc.hasTrivialDestructor() && "Expected trivial destructor");
> 
>   CapOperands = OperandCapacity::get(MI.getNumOperands());
> @@ -1677,6 +1686,12 @@ void MachineInstr::print(raw_ostream &OS
>   else
>     OS << "UNKNOWN";
> 
> +
> +#ifdef LLVM_BUILD_GLOBAL_ISEL
> +  if (Ty)
> +    OS << ' ' << *Ty << ' ';
> +#endif
> +
>   if (SkipOpers)
>     return;
> 
> 
> 
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