[llvm] r259683 - Minor performance tweaks to llvm-tblgen (and a few that might be a good idea)

[David Blaikie via llvm-commits]

On Wed, Feb 3, 2016 at 11:34 AM, Reid Kleckner via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: rnk
> Date: Wed Feb  3 13:34:28 2016
> New Revision: 259683
>
> URL: http://llvm.org/viewvc/llvm-project?rev=259683&view=rev
> Log:
> Minor performance tweaks to llvm-tblgen (and a few that might be a good
> idea)
>
> Summary:
> This patch adds a reserve call to an expensive function
> (`llvm::LoadIntrinsics`), and may fix a few other low hanging
> performance fruit (I've put them in comments for now, so we can
> discuss).
>
> **Motivation:**
>
> As I'm sure other developers do, when I build LLVM, I build the entire
> project with the same config (`Debug`, `MinSizeRel`, `Release`, or
> `RelWithDebInfo`). However, the `Debug` config also builds llvm-tblgen
> in `Debug` mode. Later build steps that run llvm-tblgen then can
> actually be the slowest steps in the entire build. Nobody likes slow
> builds.
>
> Reviewers: rnk, dblaikie
>
> Differential Revision: http://reviews.llvm.org/D16832
>
> Patch by Alexander G. Riccio
>
> Modified:
>     llvm/trunk/include/llvm/TableGen/Record.h
>     llvm/trunk/utils/TableGen/CodeGenInstruction.cpp
>     llvm/trunk/utils/TableGen/CodeGenTarget.cpp
>
> Modified: llvm/trunk/include/llvm/TableGen/Record.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/TableGen/Record.h?rev=259683&r1=259682&r2=259683&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/TableGen/Record.h (original)
> +++ llvm/trunk/include/llvm/TableGen/Record.h Wed Feb  3 13:34:28 2016
> @@ -1307,9 +1307,14 @@ public:
>    }
>
>    bool isSubClassOf(StringRef Name) const {
> -    for (const auto &SCPair : SuperClasses)
> -      if (SCPair.first->getNameInitAsString() == Name)
> +    for (const auto &SCPair : SuperClasses) {
> +      if (const auto *SI =
> dyn_cast<StringInit>(SCPair.first->getNameInit())) {
>

This is a bit more novel/noteworthy & might merit a comment about why we're
using dyn_cast to do the same work as getNameInitAsString. Perhaps.


> +        if (SI->getValue() == Name)
> +          return true;
> +      } else if (SCPair.first->getNameInitAsString() == Name) {
>          return true;
> +      }
> +    }
>      return false;
>    }
>
>
> Modified: llvm/trunk/utils/TableGen/CodeGenInstruction.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/CodeGenInstruction.cpp?rev=259683&r1=259682&r2=259683&view=diff
>
> ==============================================================================
> --- llvm/trunk/utils/TableGen/CodeGenInstruction.cpp (original)
> +++ llvm/trunk/utils/TableGen/CodeGenInstruction.cpp Wed Feb  3 13:34:28
> 2016
> @@ -49,7 +49,9 @@ CGIOperandList::CGIOperandList(Record *R
>
>    unsigned MIOperandNo = 0;
>    std::set<std::string> OperandNames;
> -  for (unsigned i = 0, e = InDI->getNumArgs()+OutDI->getNumArgs(); i !=
> e; ++i){
> +  unsigned e = InDI->getNumArgs() + OutDI->getNumArgs();
> +  OperandList.reserve(e);
> +  for (unsigned i = 0; i != e; ++i){
>      Init *ArgInit;
>      std::string ArgName;
>      if (i < NumDefs) {
>
> Modified: llvm/trunk/utils/TableGen/CodeGenTarget.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/CodeGenTarget.cpp?rev=259683&r1=259682&r2=259683&view=diff
>
> ==============================================================================
> --- llvm/trunk/utils/TableGen/CodeGenTarget.cpp (original)
> +++ llvm/trunk/utils/TableGen/CodeGenTarget.cpp Wed Feb  3 13:34:28 2016
> @@ -441,6 +441,7 @@ std::vector<CodeGenIntrinsic> llvm::Load
>    std::vector<Record*> I = RC.getAllDerivedDefinitions("Intrinsic");
>
>    std::vector<CodeGenIntrinsic> Result;
> +  Result.reserve(I.size());
>
>    for (unsigned i = 0, e = I.size(); i != e; ++i) {
>      bool isTarget = I[i]->getValueAsBit("isTarget");
> @@ -448,7 +449,7 @@ std::vector<CodeGenIntrinsic> llvm::Load
>        Result.push_back(CodeGenIntrinsic(I[i]));
>    }
>    std::sort(Result.begin(), Result.end(),
> -            [](CodeGenIntrinsic LHS, CodeGenIntrinsic RHS) {
> +            [](const CodeGenIntrinsic& LHS, const CodeGenIntrinsic& RHS) {
>                return LHS.Name < RHS.Name;
>              });
>    return Result;
>
>
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