The cost of splitting a large vector instruction is not being taken into account by the getUserCost function. This was leading to some loops being over unrolled. The cost of a vector instruction is now being multiplied by the cost of the type legalization. This will return a more accurate cost.

Committing on behalf on Brad Nemanich (brad.nemanich@ibm.com)

Differential Revision: https://reviews.llvm.org/D38961

llvm-svn: 316174

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index d3295a9d22e..52c5b688d35 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -189,6 +189,17 @@ int PPCTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
   return PPCTTIImpl::getIntImmCost(Imm, Ty);
 }
 
+unsigned PPCTTIImpl::getUserCost(const User *U,
+                                 ArrayRef<const Value *> Operands) {
+  if (U->getType()->isVectorTy()) {
+    // Instructions that need to be split should cost more.
+    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, U->getType());
+    return LT.first * BaseT::getUserCost(U, Operands);
+  }
+  
+  return BaseT::getUserCost(U, Operands);
+}
+
 void PPCTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                          TTI::UnrollingPreferences &UP) {
   if (ST->getDarwinDirective() == PPC::DIR_A2) {