[hot-cold-split] Name split functions with ".cold" suffix

Summary:
The current default of appending "_"+entry block label to the new
extracted cold function breaks demangling. Change the deliminator from
"_" to "." to enable demangling. Because the header block label will
be empty for release compile code, use "extracted" after the "." when
the label is empty.

Additionally, add a mechanism for the client to pass in an alternate
suffix applied after the ".", and have the hot cold split pass use
"cold."+Count, where the Count is currently 1 but can be used to
uniquely number multiple cold functions split out from the same function
with D53588.

Reviewers: sebpop, hiraditya

Subscribers: llvm-commits, erik.pilkington

Differential Revision: https://reviews.llvm.org/D53534

llvm-svn: 345178

1 files changed, 9 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/IPO/HotColdSplitting.cpp b/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
index d3e086e972a..a63cd842241 100644
--- a/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
+++ b/llvm/lib/Transforms/IPO/HotColdSplitting.cpp
@@ -265,7 +265,7 @@ private:
                                     DominatorTree *DT, PostDomTree *PDT);
   Function *extractColdRegion(const SmallVectorImpl<BasicBlock *> &Region,
                               DominatorTree *DT, BlockFrequencyInfo *BFI,
-                              OptimizationRemarkEmitter &ORE);
+                              OptimizationRemarkEmitter &ORE, unsigned Count);
   bool isOutlineCandidate(const SmallVectorImpl<BasicBlock *> &Region,
                           const BasicBlock *Exit) const {
     if (!Exit)
@@ -331,16 +331,18 @@ bool HotColdSplitting::shouldOutlineFrom(const Function &F) const {
   return true;
 }
 
-Function *
-HotColdSplitting::extractColdRegion(const SmallVectorImpl<BasicBlock *> &Region,
-                                    DominatorTree *DT, BlockFrequencyInfo *BFI,
-                                    OptimizationRemarkEmitter &ORE) {
+Function *HotColdSplitting::extractColdRegion(
+    const SmallVectorImpl<BasicBlock *> &Region, DominatorTree *DT,
+    BlockFrequencyInfo *BFI, OptimizationRemarkEmitter &ORE, unsigned Count) {
   assert(!Region.empty());
   LLVM_DEBUG(for (auto *BB : Region)
           llvm::dbgs() << "\nExtracting: " << *BB;);
 
   // TODO: Pass BFI and BPI to update profile information.
-  CodeExtractor CE(Region, DT);
+  CodeExtractor CE(Region, DT, /* AggregateArgs */ false, /* BFI */ nullptr,
+                   /* BPI */ nullptr, /* AllowVarArgs */ false,
+                   /* AllowAlloca */ false,
+                   /* Suffix */ "cold." + std::to_string(Count));
 
   SetVector<Value *> Inputs, Outputs, Sinks;
   CE.findInputsOutputs(Inputs, Outputs, Sinks);
@@ -426,7 +428,7 @@ const Function *HotColdSplitting::outlineColdBlocks(Function &F,
         ++NumColdSESEFound;
         ValidColdRegion.push_back(ExitColdRegion);
         // Candidate for outlining. FIXME: Continue outlining.
-        return extractColdRegion(ValidColdRegion, DT, BFI, ORE);
+        return extractColdRegion(ValidColdRegion, DT, BFI, ORE, /* Count */ 1);
       }
     }
   }