Add getUnrollingPreferences to TTI

Allow targets to customize the default behavior of the generic loop unrolling
transformation. This will be used by the PowerPC backend when targeting the A2
core (which is in-order with a deep pipeline), and using more aggressive
defaults is important.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189565 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index 06810a7de083b25d7c6966c0c571eff14847f46f..908612c6fa0cde1ab5f1ea461563a4ce5b47103b 100644 (file)
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -191,6 +191,20 @@ public:
   /// incurs significant execution cost.
   virtual bool isLoweredToCall(const Function *F) const;
 
   /// incurs significant execution cost.
   virtual bool isLoweredToCall(const Function *F) const;
 

+  /// Parameters that control the generic loop unrolling transformation.
+  struct UnrollingPreferences {
+    unsigned Threshold; ///< The cost threshold for the unrolled loop.
+    unsigned OptSizeThreshold; ///< The cost threshold for the unrolled loop
+                               ///< when optimizing for size.
+    bool     Partial;   ///< Allow partial loop unrolling.
+    bool     Runtime;   ///< Perform runtime unrolling.
+  };
+
+  /// \brief Get target-customized preferences for the generic loop unrolling
+  /// transformation. Returns true if the UnrollingPreferences struct has been
+  /// initialized.
+  virtual bool getUnrollingPreferences(UnrollingPreferences &UP) const;
+

   /// @}
 
   /// \name Scalar Target Information
   /// @}
 
   /// \name Scalar Target Information

diff --git a/lib/Analysis/TargetTransformInfo.cpp b/lib/Analysis/TargetTransformInfo.cpp
index 8c6005b31cbe4868b70fdfa66e33c69ef89b679b..b587ff27ea673dcdb354ef31abed1ce7fe7a3050 100644 (file)
--- a/lib/Analysis/TargetTransformInfo.cpp
+++ b/lib/Analysis/TargetTransformInfo.cpp
@@ -96,6 +96,11 @@ bool TargetTransformInfo::isLoweredToCall(const Function *F) const {
   return PrevTTI->isLoweredToCall(F);
 }
 
   return PrevTTI->isLoweredToCall(F);
 }
 

+bool TargetTransformInfo::getUnrollingPreferences(
+                            UnrollingPreferences &UP) const {
+  return PrevTTI->getUnrollingPreferences(UP);
+}
+

 bool TargetTransformInfo::isLegalAddImmediate(int64_t Imm) const {
   return PrevTTI->isLegalAddImmediate(Imm);
 }
 bool TargetTransformInfo::isLegalAddImmediate(int64_t Imm) const {
   return PrevTTI->isLegalAddImmediate(Imm);
 }


@@ -469,6 +474,10 @@ struct NoTTI : ImmutablePass, TargetTransformInfo {
     return true;
   }
 
     return true;
   }
 

+  virtual bool getUnrollingPreferences(UnrollingPreferences &) const {
+    return false;
+  }
+

   bool isLegalAddImmediate(int64_t Imm) const {
     return false;
   }
   bool isLegalAddImmediate(int64_t Imm) const {
     return false;
   }

diff --git a/lib/CodeGen/BasicTargetTransformInfo.cpp b/lib/CodeGen/BasicTargetTransformInfo.cpp
index d5340e60231eae4870f8fbab1a518c93e586c026..e1380b73e9ed66d2f78add13cd05aabeb7042641 100644 (file)
--- a/lib/CodeGen/BasicTargetTransformInfo.cpp
+++ b/lib/CodeGen/BasicTargetTransformInfo.cpp
@@ -84,6 +84,7 @@ public:
   virtual unsigned getJumpBufSize() const;
   virtual bool shouldBuildLookupTables() const;
   virtual bool haveFastSqrt(Type *Ty) const;
   virtual unsigned getJumpBufSize() const;
   virtual bool shouldBuildLookupTables() const;
   virtual bool haveFastSqrt(Type *Ty) const;

+  virtual bool getUnrollingPreferences(UnrollingPreferences &UP) const;

 
   /// @}
 
 
   /// @}
 


@@ -189,6 +190,10 @@ bool BasicTTI::haveFastSqrt(Type *Ty) const {
   return TLI->isTypeLegal(VT) && TLI->isOperationLegalOrCustom(ISD::FSQRT, VT);
 }
 
   return TLI->isTypeLegal(VT) && TLI->isOperationLegalOrCustom(ISD::FSQRT, VT);
 }
 

+bool BasicTTI::getUnrollingPreferences(UnrollingPreferences &) const {
+  return false;
+}
+

 //===----------------------------------------------------------------------===//
 //
 // Calls used by the vectorizers.
 //===----------------------------------------------------------------------===//
 //
 // Calls used by the vectorizers.

diff --git a/lib/Transforms/Scalar/LoopUnrollPass.cpp b/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 80d060b926eaf110db14251b661957326f476ec3..f8ff275e9699aeac2c60ae7c8ba5eab7fdc532c1 100644 (file)
--- a/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -55,6 +55,8 @@ namespace {
       CurrentAllowPartial = (P == -1) ? UnrollAllowPartial : (bool)P;
 
       UserThreshold = (T != -1) || (UnrollThreshold.getNumOccurrences() > 0);
       CurrentAllowPartial = (P == -1) ? UnrollAllowPartial : (bool)P;
 
       UserThreshold = (T != -1) || (UnrollThreshold.getNumOccurrences() > 0);

+      UserAllowPartial = (P != -1) ||
+                         (UnrollAllowPartial.getNumOccurrences() > 0);

 
       initializeLoopUnrollPass(*PassRegistry::getPassRegistry());
     }
 
       initializeLoopUnrollPass(*PassRegistry::getPassRegistry());
     }


@@ -76,6 +78,7 @@ namespace {
     unsigned CurrentThreshold;
     bool     CurrentAllowPartial;
     bool     UserThreshold;        // CurrentThreshold is user-specified.
     unsigned CurrentThreshold;
     bool     CurrentAllowPartial;
     bool     UserThreshold;        // CurrentThreshold is user-specified.

+    bool     UserAllowPartial;     // CurrentAllowPartial is user-specified.

 
     bool runOnLoop(Loop *L, LPPassManager &LPM);
 
 
     bool runOnLoop(Loop *L, LPPassManager &LPM);
 


@@ -145,16 +148,20 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
         << "] Loop %" << Header->getName() << "\n");
   (void)Header;
 
         << "] Loop %" << Header->getName() << "\n");
   (void)Header;
 

+  TargetTransformInfo::UnrollingPreferences UP;
+  bool HasUP = TTI.getUnrollingPreferences(UP);
+

   // Determine the current unrolling threshold.  While this is normally set
   // from UnrollThreshold, it is overridden to a smaller value if the current
   // function is marked as optimize-for-size, and the unroll threshold was
   // not user specified.
   // Determine the current unrolling threshold.  While this is normally set
   // from UnrollThreshold, it is overridden to a smaller value if the current
   // function is marked as optimize-for-size, and the unroll threshold was
   // not user specified.

-  unsigned Threshold = CurrentThreshold;
+  unsigned Threshold = (HasUP && !UserThreshold) ? UP.Threshold :
+                                                   CurrentThreshold;

   if (!UserThreshold &&
       Header->getParent()->getAttributes().
         hasAttribute(AttributeSet::FunctionIndex,
                      Attribute::OptimizeForSize))
   if (!UserThreshold &&
       Header->getParent()->getAttributes().
         hasAttribute(AttributeSet::FunctionIndex,
                      Attribute::OptimizeForSize))

-    Threshold = OptSizeUnrollThreshold;
+    Threshold = HasUP ? UP.OptSizeThreshold : OptSizeUnrollThreshold;

 
   // Find trip count and trip multiple if count is not available
   unsigned TripCount = 0;
 
   // Find trip count and trip multiple if count is not available
   unsigned TripCount = 0;


@@ -184,6 +191,9 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
     Count = TripCount;
   }
 
     Count = TripCount;
   }
 

+  bool Runtime = (HasUP && UnrollRuntime.getNumOccurrences() == 0) ?
+                 UP.Runtime : UnrollRuntime;
+

   // Enforce the threshold.
   if (Threshold != NoThreshold) {
     unsigned NumInlineCandidates;
   // Enforce the threshold.
   if (Threshold != NoThreshold) {
     unsigned NumInlineCandidates;


@@ -204,7 +214,9 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
     if (TripCount != 1 && Size > Threshold) {
       DEBUG(dbgs() << "  Too large to fully unroll with count: " << Count
             << " because size: " << Size << ">" << Threshold << "\n");
     if (TripCount != 1 && Size > Threshold) {
       DEBUG(dbgs() << "  Too large to fully unroll with count: " << Count
             << " because size: " << Size << ">" << Threshold << "\n");

-      if (!CurrentAllowPartial && !(UnrollRuntime && TripCount == 0)) {
+      bool AllowPartial = (HasUP && !UserAllowPartial) ? UP.Partial :
+                                                         CurrentAllowPartial;
+      if (!AllowPartial && !(Runtime && TripCount == 0)) {

         DEBUG(dbgs() << "  will not try to unroll partially because "
               << "-unroll-allow-partial not given\n");
         return false;
         DEBUG(dbgs() << "  will not try to unroll partially because "
               << "-unroll-allow-partial not given\n");
         return false;


@@ -215,7 +227,7 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
         while (Count != 0 && TripCount%Count != 0)
           Count--;
       }
         while (Count != 0 && TripCount%Count != 0)
           Count--;
       }

-      else if (UnrollRuntime) {
+      else if (Runtime) {

         // Reduce unroll count to be a lower power-of-two value
         while (Count != 0 && Size > Threshold) {
           Count >>= 1;
         // Reduce unroll count to be a lower power-of-two value
         while (Count != 0 && Size > Threshold) {
           Count >>= 1;


@@ -231,7 +243,7 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
   }
 
   // Unroll the loop.
   }
 
   // Unroll the loop.

-  if (!UnrollLoop(L, Count, TripCount, UnrollRuntime, TripMultiple, LI, &LPM))
+  if (!UnrollLoop(L, Count, TripCount, Runtime, TripMultiple, LI, &LPM))

     return false;
 
   return true;
     return false;
 
   return true;