[llvm] r279574 - [stackmaps] Extract out magic constants [NFCI]

[Mehdi Amini via llvm-commits]

Hi Philip,

I assume it is a work-in-progress, but just to let you know I have a warning with this:

/llvm/src/include/llvm/CodeGen/StackMaps.h:35:23: warning: private field 'MI' is not used [-Wunused-private-field]
  const MachineInstr *MI;
                      ^

— 
Mehdi


> On Aug 23, 2016, at 2:21 PM, Philip Reames via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Author: reames
> Date: Tue Aug 23 16:21:43 2016
> New Revision: 279574
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=279574&view=rev
> Log:
> [stackmaps] Extract out magic constants [NFCI]
> 
> This is a first step towards clarifying the exact MI semantics of stackmap's "live values".  
> 
> 
> Modified:
>    llvm/trunk/include/llvm/CodeGen/StackMaps.h
>    llvm/trunk/lib/CodeGen/StackMaps.cpp
>    llvm/trunk/lib/CodeGen/TargetInstrInfo.cpp
> 
> Modified: llvm/trunk/include/llvm/CodeGen/StackMaps.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/StackMaps.h?rev=279574&r1=279573&r2=279574&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/CodeGen/StackMaps.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/StackMaps.h Tue Aug 23 16:21:43 2016
> @@ -22,6 +22,29 @@ class AsmPrinter;
> class MCExpr;
> class MCStreamer;
> 
> +/// \brief MI-level stackmap operands.
> +///
> +/// MI slackmap operations take the form:
> +/// <id>, <numBytes>, live args...
> +class StackMapOpers {
> +public:
> +  /// Enumerate the meta operands.
> +  enum { IDPos, NBytesPos };
> +
> +private:
> +  const MachineInstr *MI;
> +
> +public:
> +  explicit StackMapOpers(const MachineInstr *MI);
> +
> +  /// Get the operand index of the variable list of non-argument operands.
> +  /// These hold the "live state".
> +  unsigned getVarIdx() const {
> +    // Skip ID, nShadowBytes.
> +    return 2;
> +  }
> +};
> +
> /// \brief MI-level patchpoint operands.
> ///
> /// MI patchpoint operations take the form:
> 
> Modified: llvm/trunk/lib/CodeGen/StackMaps.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackMaps.cpp?rev=279574&r1=279573&r2=279574&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/StackMaps.cpp (original)
> +++ llvm/trunk/lib/CodeGen/StackMaps.cpp Tue Aug 23 16:21:43 2016
> @@ -35,6 +35,12 @@ static cl::opt<int> StackMapVersion(
> 
> const char *StackMaps::WSMP = "Stack Maps: ";
> 
> +StackMapOpers::StackMapOpers(const MachineInstr *MI) 
> +  : MI(MI) {
> +  assert(getVarIdx() <= MI->getNumOperands() &&
> +         "invalid stackmap definition");
> +}
> +
> PatchPointOpers::PatchPointOpers(const MachineInstr *MI)
>     : MI(MI), HasDef(MI->getOperand(0).isReg() && MI->getOperand(0).isDef() &&
>                      !MI->getOperand(0).isImplicit()),
> @@ -343,8 +349,9 @@ void StackMaps::recordStackMapOpers(cons
> void StackMaps::recordStackMap(const MachineInstr &MI) {
>   assert(MI.getOpcode() == TargetOpcode::STACKMAP && "expected stackmap");
> 
> -  int64_t ID = MI.getOperand(0).getImm();
> -  recordStackMapOpers(MI, ID, std::next(MI.operands_begin(), 2),
> +  StackMapOpers opers(&MI);
> +  const int64_t ID = MI.getOperand(PatchPointOpers::IDPos).getImm();
> +  recordStackMapOpers(MI, ID, std::next(MI.operands_begin(), opers.getVarIdx()),
>                       MI.operands_end());
> }
> 
> @@ -352,7 +359,7 @@ void StackMaps::recordPatchPoint(const M
>   assert(MI.getOpcode() == TargetOpcode::PATCHPOINT && "expected patchpoint");
> 
>   PatchPointOpers opers(&MI);
> -  int64_t ID = opers.getMetaOper(PatchPointOpers::IDPos).getImm();
> +  const int64_t ID = opers.getMetaOper(PatchPointOpers::IDPos).getImm();
> 
>   auto MOI = std::next(MI.operands_begin(), opers.getStackMapStartIdx());
>   recordStackMapOpers(MI, ID, MOI, MI.operands_end(),
> 
> Modified: llvm/trunk/lib/CodeGen/TargetInstrInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetInstrInfo.cpp?rev=279574&r1=279573&r2=279574&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/TargetInstrInfo.cpp (original)
> +++ llvm/trunk/lib/CodeGen/TargetInstrInfo.cpp Tue Aug 23 16:21:43 2016
> @@ -437,11 +437,15 @@ static MachineInstr *foldPatchpoint(Mach
>                                     const TargetInstrInfo &TII) {
>   unsigned StartIdx = 0;
>   switch (MI.getOpcode()) {
> -  case TargetOpcode::STACKMAP:
> -    StartIdx = 2; // Skip ID, nShadowBytes.
> +  case TargetOpcode::STACKMAP: {
> +    // StackMapLiveValues are foldable
> +    StackMapOpers opers(&MI);
> +    StartIdx = opers.getVarIdx();
>     break;
> +  }
>   case TargetOpcode::PATCHPOINT: {
> -    // For PatchPoint, the call args are not foldable.
> +    // For PatchPoint, the call args are not foldable (even if reported in the
> +    // stackmap e.g. via anyregcc).
>     PatchPointOpers opers(&MI);
>     StartIdx = opers.getVarIdx();
>     break;
> 
> 
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