1 files changed, 97 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index c0409206216e..a7b1953ce81c 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -16,7 +16,6 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/Triple.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
@@ -47,6 +46,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include <algorithm>
@@ -421,6 +421,9 @@ bool InstrProfiling::lowerIntrinsics(Function *F) {
       } else if (auto *IPI = dyn_cast<InstrProfIncrementInst>(&Instr)) {
         lowerIncrement(IPI);
         MadeChange = true;
+      } else if (auto *IPC = dyn_cast<InstrProfTimestampInst>(&Instr)) {
+        lowerTimestamp(IPC);
+        MadeChange = true;
       } else if (auto *IPC = dyn_cast<InstrProfCoverInst>(&Instr)) {
         lowerCover(IPC);
         MadeChange = true;
@@ -510,6 +513,7 @@ static bool containsProfilingIntrinsics(Module &M) {
   return containsIntrinsic(llvm::Intrinsic::instrprof_cover) ||
          containsIntrinsic(llvm::Intrinsic::instrprof_increment) ||
          containsIntrinsic(llvm::Intrinsic::instrprof_increment_step) ||
+         containsIntrinsic(llvm::Intrinsic::instrprof_timestamp) ||
          containsIntrinsic(llvm::Intrinsic::instrprof_value_profile);
 }
 
@@ -540,18 +544,19 @@ bool InstrProfiling::run(
   // the instrumented function. This is counting the number of instrumented
   // target value sites to enter it as field in the profile data variable.
   for (Function &F : M) {
-    InstrProfIncrementInst *FirstProfIncInst = nullptr;
+    InstrProfInstBase *FirstProfInst = nullptr;
     for (BasicBlock &BB : F)
       for (auto I = BB.begin(), E = BB.end(); I != E; I++)
         if (auto *Ind = dyn_cast<InstrProfValueProfileInst>(I))
           computeNumValueSiteCounts(Ind);
-        else if (FirstProfIncInst == nullptr)
-          FirstProfIncInst = dyn_cast<InstrProfIncrementInst>(I);
+        else if (FirstProfInst == nullptr &&
+                 (isa<InstrProfIncrementInst>(I) || isa<InstrProfCoverInst>(I)))
+          FirstProfInst = dyn_cast<InstrProfInstBase>(I);
 
     // Value profiling intrinsic lowering requires per-function profile data
     // variable to be created first.
-    if (FirstProfIncInst != nullptr)
-      static_cast<void>(getOrCreateRegionCounters(FirstProfIncInst));
+    if (FirstProfInst != nullptr)
+      static_cast<void>(getOrCreateRegionCounters(FirstProfInst));
   }
 
   for (Function &F : M)
@@ -669,6 +674,9 @@ Value *InstrProfiling::getCounterAddress(InstrProfInstBase *I) {
   auto *Counters = getOrCreateRegionCounters(I);
   IRBuilder<> Builder(I);
 
+  if (isa<InstrProfTimestampInst>(I))
+    Counters->setAlignment(Align(8));
+
   auto *Addr = Builder.CreateConstInBoundsGEP2_32(
       Counters->getValueType(), Counters, 0, I->getIndex()->getZExtValue());
 
@@ -710,6 +718,21 @@ void InstrProfiling::lowerCover(InstrProfCoverInst *CoverInstruction) {
   CoverInstruction->eraseFromParent();
 }
 
+void InstrProfiling::lowerTimestamp(
+    InstrProfTimestampInst *TimestampInstruction) {
+  assert(TimestampInstruction->getIndex()->isZeroValue() &&
+         "timestamp probes are always the first probe for a function");
+  auto &Ctx = M->getContext();
+  auto *TimestampAddr = getCounterAddress(TimestampInstruction);
+  IRBuilder<> Builder(TimestampInstruction);
+  auto *CalleeTy =
+      FunctionType::get(Type::getVoidTy(Ctx), TimestampAddr->getType(), false);
+  auto Callee = M->getOrInsertFunction(
+      INSTR_PROF_QUOTE(INSTR_PROF_PROFILE_SET_TIMESTAMP), CalleeTy);
+  Builder.CreateCall(Callee, {TimestampAddr});
+  TimestampInstruction->eraseFromParent();
+}
+
 void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
   auto *Addr = getCounterAddress(Inc);
 
@@ -823,6 +846,72 @@ static inline bool shouldRecordFunctionAddr(Function *F) {
   return F->hasAddressTaken() || F->hasLinkOnceLinkage();
 }
 
+static inline bool shouldUsePublicSymbol(Function *Fn) {
+  // It isn't legal to make an alias of this function at all
+  if (Fn->isDeclarationForLinker())
+    return true;
+
+  // Symbols with local linkage can just use the symbol directly without
+  // introducing relocations
+  if (Fn->hasLocalLinkage())
+    return true;
+
+  // PGO + ThinLTO + CFI cause duplicate symbols to be introduced due to some
+  // unfavorable interaction between the new alias and the alias renaming done
+  // in LowerTypeTests under ThinLTO. For comdat functions that would normally
+  // be deduplicated, but the renaming scheme ends up preventing renaming, since
+  // it creates unique names for each alias, resulting in duplicated symbols. In
+  // the future, we should update the CFI related passes to migrate these
+  // aliases to the same module as the jump-table they refer to will be defined.
+  if (Fn->hasMetadata(LLVMContext::MD_type))
+    return true;
+
+  // For comdat functions, an alias would need the same linkage as the original
+  // function and hidden visibility. There is no point in adding an alias with
+  // identical linkage an visibility to avoid introducing symbolic relocations.
+  if (Fn->hasComdat() &&
+      (Fn->getVisibility() == GlobalValue::VisibilityTypes::HiddenVisibility))
+    return true;
+
+  // its OK to use an alias
+  return false;
+}
+
+static inline Constant *getFuncAddrForProfData(Function *Fn) {
+  auto *Int8PtrTy = Type::getInt8PtrTy(Fn->getContext());
+  // Store a nullptr in __llvm_profd, if we shouldn't use a real address
+  if (!shouldRecordFunctionAddr(Fn))
+    return ConstantPointerNull::get(Int8PtrTy);
+
+  // If we can't use an alias, we must use the public symbol, even though this
+  // may require a symbolic relocation.
+  if (shouldUsePublicSymbol(Fn))
+    return ConstantExpr::getBitCast(Fn, Int8PtrTy);
+
+  // When possible use a private alias to avoid symbolic relocations.
+  auto *GA = GlobalAlias::create(GlobalValue::LinkageTypes::PrivateLinkage,
+                                 Fn->getName() + ".local", Fn);
+
+  // When the instrumented function is a COMDAT function, we cannot use a
+  // private alias. If we did, we would create reference to a local label in
+  // this function's section. If this version of the function isn't selected by
+  // the linker, then the metadata would introduce a reference to a discarded
+  // section. So, for COMDAT functions, we need to adjust the linkage of the
+  // alias. Using hidden visibility avoids a dynamic relocation and an entry in
+  // the dynamic symbol table.
+  //
+  // Note that this handles COMDAT functions with visibility other than Hidden,
+  // since that case is covered in shouldUsePublicSymbol()
+  if (Fn->hasComdat()) {
+    GA->setLinkage(Fn->getLinkage());
+    GA->setVisibility(GlobalValue::VisibilityTypes::HiddenVisibility);
+  }
+
+  // appendToCompilerUsed(*Fn->getParent(), {GA});
+
+  return ConstantExpr::getBitCast(GA, Int8PtrTy);
+}
+
 static bool needsRuntimeRegistrationOfSectionRange(const Triple &TT) {
   // Don't do this for Darwin.  compiler-rt uses linker magic.
   if (TT.isOSDarwin())
@@ -1014,9 +1103,7 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfInstBase *Inc) {
   };
   auto *DataTy = StructType::get(Ctx, ArrayRef(DataTypes));
 
-  Constant *FunctionAddr = shouldRecordFunctionAddr(Fn)
-                               ? ConstantExpr::getBitCast(Fn, Int8PtrTy)
-                               : ConstantPointerNull::get(Int8PtrTy);
+  Constant *FunctionAddr = getFuncAddrForProfData(Fn);
 
   Constant *Int16ArrayVals[IPVK_Last + 1];
   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)
@@ -1116,6 +1203,7 @@ void InstrProfiling::emitVNodes() {
       Constant::getNullValue(VNodesTy), getInstrProfVNodesVarName());
   VNodesVar->setSection(
       getInstrProfSectionName(IPSK_vnodes, TT.getObjectFormat()));
+  VNodesVar->setAlignment(M->getDataLayout().getABITypeAlign(VNodesTy));
   // VNodesVar is used by runtime but not referenced via relocation by other
   // sections. Conservatively make it linker retained.
   UsedVars.push_back(VNodesVar);