Encode duplication factor from loop vectorization and loop unrolling to discriminator.

Summary:
This patch starts the implementation as discuss in the following RFC: http://lists.llvm.org/pipermail/llvm-dev/2016-October/106532.html

When optimization duplicates code that will scale down the execution count of a basic block, we will record the duplication factor as part of discriminator so that the offline process tool can find the duplication factor and collect the accurate execution frequency of the corresponding source code. Two important optimization that fall into this category is loop vectorization and loop unroll. This patch records the duplication factor for these 2 optimizations.

The recording will be guarded by a flag encode-duplication-in-discriminators, which is off by default.

Reviewers: probinson, aprantl, davidxl, hfinkel, echristo

Reviewed By: hfinkel

Subscribers: mehdi_amini, anemet, mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D26420

llvm-svn: 294782

1 files changed, 12 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 59e7f38cdb8..401b942d307 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -616,6 +616,10 @@ protected:
   /// vector of instructions.
   void addMetadata(ArrayRef<Value *> To, Instruction *From);
 
+  /// \brief Set the debug location in the builder using the debug location in
+  /// the instruction.
+  void setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr);
+
   /// This is a helper class for maintaining vectorization state. It's used for
   /// mapping values from the original loop to their corresponding values in
   /// the new loop. Two mappings are maintained: one for vectorized values and
@@ -865,12 +869,14 @@ static Instruction *getDebugLocFromInstOrOperands(Instruction *I) {
   return I;
 }
 
-/// \brief Set the debug location in the builder using the debug location in the
-/// instruction.
-static void setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr) {
-  if (const Instruction *Inst = dyn_cast_or_null<Instruction>(Ptr))
-    B.SetCurrentDebugLocation(Inst->getDebugLoc());
-  else
+void InnerLoopVectorizer::setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr) {
+  if (const Instruction *Inst = dyn_cast_or_null<Instruction>(Ptr)) {
+    const DILocation *DIL = Inst->getDebugLoc();
+    if (DIL && Inst->getFunction()->isDebugInfoForProfiling())
+      B.SetCurrentDebugLocation(DIL->cloneWithDuplicationFactor(UF * VF));
+    else
+      B.SetCurrentDebugLocation(DIL);
+  } else
     B.SetCurrentDebugLocation(DebugLoc());
 }