[llvm-commits] [llvm] r167759 - in /llvm/trunk: include/llvm/PassManagers.h lib/VMCore/PassManager.cpp

[Benjamin Kramer]

On 12.11.2012, at 22:42, Evan Cheng <evan.cheng at apple.com> wrote:

> Author: evancheng
> Date: Mon Nov 12 15:42:53 2012
> New Revision: 167759
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=167759&view=rev
> Log:
> Cache size of PassVector to speed up getNumContainedPasses().
> getNumContainedPasses() used to compute the size of the vector on demand. It is
> called repeated in loops (such as runOnFunction()) and it can be updated while
> inside the loop.

Do you have some numbers to back this change? Getting the size of a small vector is loading two pointers, a sub and a shift. That shouldn't be expensive enough to justify adding more code.

OTOH, the call to size() is inside a virtual function, and I don't think that any of the calls to it can be devirtualized. I'd expect the lack of inlining and the indirect call to be a lot slower than the arithmetic in size(). However, it looks like getNumContainedPasses() isn't overridden anywhere so maybe we should just make it non-virtual if it's popping up in profiles?

- Ben

> 
> Modified:
>    llvm/trunk/include/llvm/PassManagers.h
>    llvm/trunk/lib/VMCore/PassManager.cpp
> 
> Modified: llvm/trunk/include/llvm/PassManagers.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/PassManagers.h?rev=167759&r1=167758&r2=167759&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/PassManagers.h (original)
> +++ llvm/trunk/include/llvm/PassManagers.h Mon Nov 12 15:42:53 2012
> @@ -263,7 +263,7 @@
> class PMDataManager {
> public:
> 
> -  explicit PMDataManager() : TPM(NULL), Depth(0) {
> +  explicit PMDataManager() : TPM(NULL), PassVectorSize(0), Depth(0) {
>     initializeAnalysisInfo();
>   }
> 
> @@ -344,7 +344,7 @@
>   void dumpPreservedSet(const Pass *P) const;
> 
>   virtual unsigned getNumContainedPasses() const {
> -    return (unsigned)PassVector.size();
> +    return PassVectorSize;
>   }
> 
>   virtual PassManagerType getPassManagerType() const {
> @@ -369,14 +369,16 @@
>   // Top level manager.
>   PMTopLevelManager *TPM;
> 
> -  // Collection of pass that are managed by this manager
> -  SmallVector<Pass *, 16> PassVector;
> -
>   // Collection of Analysis provided by Parent pass manager and
>   // used by current pass manager. At at time there can not be more
>   // then PMT_Last active pass mangers.
>   std::map<AnalysisID, Pass *> *InheritedAnalysis[PMT_Last];
> 
> +  // Collection of pass that are managed by this manager
> +  SmallVector<Pass *, 16> PassVector;
> +
> +  // Cache the size of PassVector
> +  unsigned PassVectorSize;
> 
>   /// isPassDebuggingExecutionsOrMore - Return true if -debug-pass=Executions
>   /// or higher is specified.
> @@ -444,7 +446,7 @@
>   }
> 
>   FunctionPass *getContainedPass(unsigned N) {
> -    assert ( N < PassVector.size() && "Pass number out of range!");
> +    assert ( N < PassVectorSize && "Pass number out of range!");
>     FunctionPass *FP = static_cast<FunctionPass *>(PassVector[N]);
>     return FP;
>   }
> 
> Modified: llvm/trunk/lib/VMCore/PassManager.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/PassManager.cpp?rev=167759&r1=167758&r2=167759&view=diff
> ==============================================================================
> --- llvm/trunk/lib/VMCore/PassManager.cpp (original)
> +++ llvm/trunk/lib/VMCore/PassManager.cpp Mon Nov 12 15:42:53 2012
> @@ -195,7 +195,7 @@
>   }
> 
>   BasicBlockPass *getContainedPass(unsigned N) {
> -    assert(N < PassVector.size() && "Pass number out of range!");
> +    assert(N < PassVectorSize && "Pass number out of range!");
>     BasicBlockPass *BP = static_cast<BasicBlockPass *>(PassVector[N]);
>     return BP;
>   }
> @@ -346,7 +346,7 @@
>   }
> 
>   ModulePass *getContainedPass(unsigned N) {
> -    assert(N < PassVector.size() && "Pass number out of range!");
> +    assert(N < PassVectorSize && "Pass number out of range!");
>     return static_cast<ModulePass *>(PassVector[N]);
>   }
> 
> @@ -963,6 +963,7 @@
>   if (!ProcessAnalysis) {
>     // Add pass
>     PassVector.push_back(P);
> +    ++PassVectorSize;
>     return;
>   }
> 
> @@ -1024,6 +1025,7 @@
> 
>   // Add pass
>   PassVector.push_back(P);
> +  ++PassVectorSize;
> }
> 
> 
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits