[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, 11 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 27b982578c4..328fe1fac65 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -228,19 +228,21 @@ buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
 CodeExtractor::CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
                              bool AggregateArgs, BlockFrequencyInfo *BFI,
                              BranchProbabilityInfo *BPI, bool AllowVarArgs,
-                             bool AllowAlloca)
+                             bool AllowAlloca, std::string Suffix)
     : DT(DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
       BPI(BPI), AllowVarArgs(AllowVarArgs),
-      Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs, AllowAlloca)) {}
+      Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs, AllowAlloca)),
+      Suffix(Suffix) {}
 
 CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs,
                              BlockFrequencyInfo *BFI,
-                             BranchProbabilityInfo *BPI)
+                             BranchProbabilityInfo *BPI, std::string Suffix)
     : DT(&DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
       BPI(BPI), AllowVarArgs(false),
       Blocks(buildExtractionBlockSet(L.getBlocks(), &DT,
                                      /* AllowVarArgs */ false,
-                                     /* AllowAlloca */ false)) {}
+                                     /* AllowAlloca */ false)),
+      Suffix(Suffix) {}
 
 /// definedInRegion - Return true if the specified value is defined in the
 /// extracted region.
@@ -669,10 +671,14 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
                   FunctionType::get(RetTy, paramTy,
                                     AllowVarArgs && oldFunction->isVarArg());
 
+  std::string SuffixToUse =
+      Suffix.empty()
+          ? (header->getName().empty() ? "extracted" : header->getName().str())
+          : Suffix;
   // Create the new function
   Function *newFunction = Function::Create(
       funcType, GlobalValue::InternalLinkage, oldFunction->getAddressSpace(),
-      oldFunction->getName() + "_" + header->getName(), M);
+      oldFunction->getName() + "." + SuffixToUse, M);
   // If the old function is no-throw, so is the new one.
   if (oldFunction->doesNotThrow())
     newFunction->setDoesNotThrow();