[llvm] r269654 - [LAA] Add option to disable conflict detection (NFC)

[Matthew Simpson via llvm-commits]

Adam,

No problem. I'll rename the flag in a follow-on.

-- Matt

-----Original Message-----
From: anemet at apple.com [mailto:anemet at apple.com] 
Sent: Monday, May 16, 2016 12:21 PM
To: Matthew Simpson <mssimpso at codeaurora.org>
Cc: llvm-commits at lists.llvm.org
Subject: Re: [llvm] r269654 - [LAA] Add option to disable conflict detection
(NFC)


> On May 16, 2016, at 7:14 AM, Matthew Simpson via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> 
> Author: mssimpso
> Date: Mon May 16 09:14:49 2016
> New Revision: 269654
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=269654&view=rev
> Log:
> [LAA] Add option to disable conflict detection (NFC)
> 
> Modified:
>    llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp
> 
> Modified: llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp
> URL: 
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LoopAccess
> Analysis.cpp?rev=269654&r1=269653&r2=269654&view=diff
> ======================================================================
> ========
> --- llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp (original)
> +++ llvm/trunk/lib/Analysis/LoopAccessAnalysis.cpp Mon May 16 09:14:49 
> +++ 2016
> @@ -65,6 +65,13 @@ static cl::opt<unsigned>
>                             "loop-access analysis (default = 100)"),
>                    cl::init(100));
> 
> +/// \brief Enable the conflict detection optimization. This option 
> +can be /// disabled for correctness testing.
> +static cl::opt<bool> EnableConflictDetection(
> +    "enable-conflict-detection", cl::Hidden,
> +    cl::desc("Enable conflict detection in loop-access analysis"),
> +    cl::init(true));

Hi Matt,

Sorry for the confusion, I meant,
-store-to-load-forwarding-conflict-detection (conflict-detection is too
general).

Thanks,
Adam

> +
> bool VectorizerParams::isInterleaveForced() {
>   return ::VectorizationInterleave.getNumOccurrences() > 0; } @@ 
> -1203,7 +1210,7 @@ MemoryDepChecker::isDependent(const MemA
>   const APInt &Val = C->getAPInt();
>   if (Val.isNegative()) {
>     bool IsTrueDataDependence = (AIsWrite && !BIsWrite);
> -    if (IsTrueDataDependence &&
> +    if (IsTrueDataDependence && EnableConflictDetection &&
>         (couldPreventStoreLoadForward(Val.abs().getZExtValue(),
TypeByteSize) ||
>          ATy != BTy)) {
>       DEBUG(dbgs() << "LAA: Forward but may prevent st->ld 
> forwarding\n"); @@ -1309,7 +1316,7 @@ MemoryDepChecker::isDependent(const
MemA
>       Distance < MaxSafeDepDistBytes ? Distance : MaxSafeDepDistBytes;
> 
>   bool IsTrueDataDependence = (!AIsWrite && BIsWrite);
> -  if (IsTrueDataDependence &&
> +  if (IsTrueDataDependence && EnableConflictDetection &&
>       couldPreventStoreLoadForward(Distance, TypeByteSize))
>     return Dependence::BackwardVectorizableButPreventsForwarding;
> 
> 
> 
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