[llvm-commits] [llvm] r170051 - in /llvm/trunk: lib/Transforms/Vectorize/LoopVectorize.cpp lib/Transforms/Vectorize/LoopVectorize.h test/Transforms/LoopVectorize/X86/conversion-cost.ll

[Nadav Rotem]

Author: nadav
Date: Wed Dec 12 18:21:03 2012
New Revision: 170051

URL: http://llvm.org/viewvc/llvm-project?rev=170051&view=rev
Log:
Teach the cost model about the optimization in r169904: Truncation of induction variables costs the same as scalar trunc. 

Modified:
    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.h
    llvm/trunk/test/Transforms/LoopVectorize/X86/conversion-cost.ll

Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=170051&r1=170050&r2=170051&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Wed Dec 12 18:21:03 2012
@@ -106,8 +106,7 @@
     }
 
     DEBUG(dbgs() << "LV: Found a vectorizable loop ("<< VF << ") in "<<
-          L->getHeader()->getParent()->getParent()->getModuleIdentifier()<<
-          "\n");
+          F->getParent()->getModuleIdentifier()<<"\n");
 
     // If we decided that it is *legal* to vectorizer the loop then do it.
     InnerLoopVectorizer LB(L, SE, LI, DT, DL, VF);
@@ -1849,6 +1848,15 @@
   return NoInduction;
 }
 
+bool LoopVectorizationLegality::isInductionVariable(const Value *V) {
+  Value *In0 = const_cast<Value*>(V);
+  PHINode *PN = dyn_cast_or_null<PHINode>(In0);
+  if (!PN)
+    return false;
+
+  return Inductions.count(PN);
+}
+
 bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB)  {
   assert(TheLoop->contains(BB) && "Unknown block used");
 
@@ -2110,6 +2118,13 @@
   case Instruction::Trunc:
   case Instruction::FPTrunc:
   case Instruction::BitCast: {
+    // We optimize the truncation of induction variable.
+    // The cost of these is the same as the scalar operation.
+    if (I->getOpcode() == Instruction::Trunc &&
+        Legal->isInductionVariable(I->getOperand(0)))
+         return VTTI->getCastInstrCost(I->getOpcode(), I->getType(),
+                                       I->getOperand(0)->getType());
+
     Type *SrcVecTy = ToVectorTy(I->getOperand(0)->getType(), VF);
     return VTTI->getCastInstrCost(I->getOpcode(), VectorTy, SrcVecTy);
   }

Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.h?rev=170051&r1=170050&r2=170051&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.h (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.h Wed Dec 12 18:21:03 2012
@@ -320,6 +320,9 @@
   /// Returns the induction variables found in the loop.
   InductionList *getInductionVars() { return &Inductions; }
 
+  /// Returns True if V is an induction variable in this loop.
+  bool isInductionVariable(const Value *V);
+
   /// Return true if the block BB needs to be predicated in order for the loop
   /// to be vectorized.
   bool blockNeedsPredication(BasicBlock *BB);

Modified: llvm/trunk/test/Transforms/LoopVectorize/X86/conversion-cost.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/X86/conversion-cost.ll?rev=170051&r1=170050&r2=170051&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/X86/conversion-cost.ll (original)
+++ llvm/trunk/test/Transforms/LoopVectorize/X86/conversion-cost.ll Wed Dec 12 18:21:03 2012
@@ -4,7 +4,7 @@
 target triple = "x86_64-apple-macosx10.8.0"
 
 ;CHECK: @conversion_cost1
-;CHECK: store <2 x i8>
+;CHECK: store <8 x i8>
 ;CHECK: ret
 define i32 @conversion_cost1(i32 %n, i8* nocapture %A, float* nocapture %B) nounwind uwtable ssp {
   %1 = icmp sgt i32 %n, 3