[polly] r262033 - ScopDetect/Info: Add option to disable invariant load hoisting

[Johannes Doerfert via llvm-commits]

On 02/26, Tobias Grosser via llvm-commits wrote:
> Author: grosser
> Date: Fri Feb 26 10:43:35 2016
> New Revision: 262033
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=262033&view=rev
> Log:
> ScopDetect/Info: Add option to disable invariant load hoisting
> 
> This is helpful for test case reduction and other experiments.
> 
> Modified:
>     polly/trunk/include/polly/ScopDetection.h
>     polly/trunk/lib/Analysis/ScopDetection.cpp
>     polly/trunk/lib/Analysis/ScopInfo.cpp
> 
> Modified: polly/trunk/include/polly/ScopDetection.h
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/ScopDetection.h?rev=262033&r1=262032&r2=262033&view=diff
> ==============================================================================
> --- polly/trunk/include/polly/ScopDetection.h (original)
> +++ polly/trunk/include/polly/ScopDetection.h Fri Feb 26 10:43:35 2016
> @@ -110,6 +110,7 @@ extern bool PollyTrackFailures;
>  extern bool PollyDelinearize;
>  extern bool PollyUseRuntimeAliasChecks;
>  extern bool PollyProcessUnprofitable;
> +extern bool PollyInvariantLoadHoisting;
>  
>  /// @brief A function attribute which will cause Polly to skip the function
>  extern llvm::StringRef PollySkipFnAttr;
> 
> Modified: polly/trunk/lib/Analysis/ScopDetection.cpp
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopDetection.cpp?rev=262033&r1=262032&r2=262033&view=diff
> ==============================================================================
> --- polly/trunk/lib/Analysis/ScopDetection.cpp (original)
> +++ polly/trunk/lib/Analysis/ScopDetection.cpp Fri Feb 26 10:43:35 2016
> @@ -171,6 +171,12 @@ static cl::opt<bool>
>                  cl::Hidden, cl::init(false), cl::ZeroOrMore,
>                  cl::cat(PollyCategory));
>  
> +bool polly::PollyInvariantLoadHoisting;
> +static cl::opt<bool, true> XPollyInvariantLoadHoisting(
> +    "polly-invariant-load-hoisting", cl::desc("Hoist invariant loads."),
> +    cl::location(PollyInvariantLoadHoisting), cl::Hidden, cl::ZeroOrMore,
> +    cl::init(true), cl::cat(PollyCategory));
> +
>  /// @brief The minimal trip count under which loops are considered unprofitable.
>  static const unsigned MIN_LOOP_TRIP_COUNT = 8;
>  
> @@ -304,6 +310,9 @@ bool ScopDetection::onlyValidRequiredInv
>      InvariantLoadsSetTy &RequiredILS, DetectionContext &Context) const {
>    Region &CurRegion = Context.CurRegion;
>  
> +  if (!PollyInvariantLoadHoisting && !RequiredILS.empty())
> +    return false;
> +
>    for (LoadInst *Load : RequiredILS)
>      if (!isHoistableLoad(Load, CurRegion, *LI, *SE))
>        return false;
> 
> Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=262033&r1=262032&r2=262033&view=diff
> ==============================================================================
> --- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
> +++ polly/trunk/lib/Analysis/ScopInfo.cpp Fri Feb 26 10:43:35 2016
> @@ -3116,27 +3116,28 @@ void Scop::verifyInvariantLoads(ScopDete
>  }
>  
>  void Scop::hoistInvariantLoads(ScopDetection &SD) {
> -  isl_union_map *Writes = getWrites();
> -  for (ScopStmt &Stmt : *this) {
> -
> -    MemoryAccessList InvariantAccesses;
> -
> -    for (MemoryAccess *Access : Stmt)
> -      if (isHoistableAccess(Access, Writes))
> -        InvariantAccesses.push_front(Access);
> -
> -    // We inserted invariant accesses always in the front but need them to be
> -    // sorted in a "natural order". The statements are already sorted in reverse
> -    // post order and that suffices for the accesses too. The reason we require
> -    // an order in the first place is the dependences between invariant loads
> -    // that can be caused by indirect loads.
> -    InvariantAccesses.reverse();
> -
> -    // Transfer the memory access from the statement to the SCoP.
> -    Stmt.removeMemoryAccesses(InvariantAccesses);
> -    addInvariantLoads(Stmt, InvariantAccesses);
> +  if (PollyInvariantLoadHoisting) {
> +    isl_union_map *Writes = getWrites();
> +    for (ScopStmt &Stmt : *this) {
> +      MemoryAccessList InvariantAccesses;
> +
> +      for (MemoryAccess *Access : Stmt)
> +        if (isHoistableAccess(Access, Writes))
> +          InvariantAccesses.push_front(Access);
> +
> +      // We inserted invariant accesses always in the front but need them to be
> +      // sorted in a "natural order". The statements are already sorted in
> +      // reverse post order and that suffices for the accesses too. The reason
> +      // we require an order in the first place is the dependences between
> +      // invariant loads that can be caused by indirect loads.
> +      InvariantAccesses.reverse();
> +
> +      // Transfer the memory access from the statement to the SCoP.
> +      Stmt.removeMemoryAccesses(InvariantAccesses);
> +      addInvariantLoads(Stmt, InvariantAccesses);
> +    }
> +    isl_union_map_free(Writes);
>    }
> -  isl_union_map_free(Writes);
>  
>    verifyInvariantLoads(SD);
>  }

Just for the sake of completeness:

if (!PollyInvariantLoadHoisting) {
  verifyInvariantLoads(SD);
  return;
}

Would have allowed to keep the old (smaller) indention.

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