[InstrFDO][TypeProf] Implement binary instrumentation and profile read/write

compiler-rt/test/profile/Linux/instrprof-vtable-value-prof.cpp

@@ -0,0 +1,145 @@
+// REQUIRES: lld-available
+
+// RUN: rm -rf %t && split-file %s %t && cd %t
+//
+// RUN: %clangxx_pgogen -fuse-ld=lld -O2 -g -fprofile-generate=. -mllvm -enable-vtable-value-profiling test.cpp -o test
+// RUN: env LLVM_PROFILE_FILE=test.profraw ./test
+
+// Show vtable profiles from raw profile.
+// RUN: llvm-profdata show --function=main --ic-targets -show-vtables test.profraw | FileCheck %s --check-prefixes=COMMON,RAW
+
+// Generate indexed profile from raw profile and show the data.
+// RUN: llvm-profdata merge test.profraw -o test.profdata
+// RUN: llvm-profdata show --function=main --ic-targets --show-vtables test.profdata | FileCheck %s --check-prefixes=COMMON,INDEXED
+
+// Generate text profile from raw and indexed profiles respectively and show the data.
+// RUN: llvm-profdata merge --text test.profraw -o raw.proftext
+// RUN: llvm-profdata show --function=main --ic-targets --show-vtables --text raw.proftext | FileCheck %s --check-prefix=ICTEXT
+// RUN: llvm-profdata merge --text test.profdata -o indexed.proftext
+// RUN: llvm-profdata show --function=main --ic-targets --show-vtables --text indexed.proftext | FileCheck %s --check-prefix=ICTEXT
+
+// Generate indexed profile from text profiles and show the data
+// RUN: llvm-profdata merge --binary raw.proftext -o text.profraw
+// RUN: llvm-profdata show --function=main --ic-targets --show-vtables text.profraw | FileCheck %s --check-prefixes=COMMON,INDEXED
+// RUN: llvm-profdata merge --binary indexed.proftext -o text.profdata
+// RUN: llvm-profdata show --function=main --ic-targets --show-vtables text.profdata | FileCheck %s --check-prefixes=COMMON,INDEXED
+
+// COMMON: Counters:
+// COMMON-NEXT:  main:
+// COMMON-NEXT:  Hash: 0x0f9a16fe6d398548
+// COMMON-NEXT:  Counters: 2
+// COMMON-NEXT:  Indirect Call Site Count: 2
+// COMMON-NEXT:  Number of instrumented vtables: 2
+// RAW:  Indirect Target Results:
+// RAW-NEXT:       [  0, _ZN8Derived15func1Eii,        250 ] (25.00%)
+// RAW-NEXT:       [  0, test.cpp;_ZN12_GLOBAL__N_18Derived25func1Eii,        750 ] (75.00%)
+// RAW-NEXT:       [  1, _ZN8Derived15func2Eii,        250 ] (25.00%)
+// RAW-NEXT:       [  1, test.cpp;_ZN12_GLOBAL__N_18Derived25func2Eii,        750 ] (75.00%)
+// RAW-NEXT:  VTable Results:
+// RAW-NEXT:       [  0, _ZTV8Derived1,        250 ] (25.00%)
+// RAW-NEXT:       [  0, test.cpp;_ZTVN12_GLOBAL__N_18Derived2E,        750 ] (75.00%)
+// RAW-NEXT:       [  1, _ZTV8Derived1,        250 ] (25.00%)
+// RAW-NEXT:       [  1, test.cpp;_ZTVN12_GLOBAL__N_18Derived2E,        750 ] (75.00%)
+// INDEXED:     Indirect Target Results:
+// INDEXED-NEXT:         [  0, test.cpp;_ZN12_GLOBAL__N_18Derived25func1Eii,        750 ] (75.00%)
+// INDEXED-NEXT:         [  0, _ZN8Derived15func1Eii,        250 ] (25.00%)
+// INDEXED-NEXT:         [  1, test.cpp;_ZN12_GLOBAL__N_18Derived25func2Eii,        750 ] (75.00%)
+// INDEXED-NEXT:         [  1, _ZN8Derived15func2Eii,        250 ] (25.00%)
+// INDEXED-NEXT:     VTable Results:
+// INDEXED-NEXT:         [  0, test.cpp;_ZTVN12_GLOBAL__N_18Derived2E,        750 ] (75.00%)
+// INDEXED-NEXT:         [  0, _ZTV8Derived1,        250 ] (25.00%)
+// INDEXED-NEXT:         [  1, test.cpp;_ZTVN12_GLOBAL__N_18Derived2E,        750 ] (75.00%)
+// INDEXED-NEXT:         [  1, _ZTV8Derived1,        250 ] (25.00%)
+// COMMON: Instrumentation level: IR  entry_first = 0
+// COMMON-NEXT: Functions shown: 1
+// COMMON-NEXT: Total functions: 6
+// COMMON-NEXT: Maximum function count: 1000
+// COMMON-NEXT: Maximum internal block count: 250
+// COMMON-NEXT: Statistics for indirect call sites profile:
+// COMMON-NEXT:   Total number of sites: 2
+// COMMON-NEXT:   Total number of sites with values: 2
+// COMMON-NEXT:   Total number of profiled values: 4
+// COMMON-NEXT:   Value sites histogram:
+// COMMON-NEXT:         NumTargets, SiteCount
+// COMMON-NEXT:         2, 2
+// COMMON-NEXT: Statistics for vtable profile:
+// COMMON-NEXT:   Total number of sites: 2
+// COMMON-NEXT:   Total number of sites with values: 2
+// COMMON-NEXT:   Total number of profiled values: 4
+// COMMON-NEXT:   Value sites histogram:
+// COMMON-NEXT:         NumTargets, SiteCount
+// COMMON-NEXT:         2, 2
+
+// ICTEXT: :ir
+// ICTEXT: main
+// ICTEXT: # Func Hash:
+// ICTEXT: 1124236338992350536
+// ICTEXT: # Num Counters:
+// ICTEXT: 2
+// ICTEXT: # Counter Values:
+// ICTEXT: 1000
+// ICTEXT: 1
+// ICTEXT: # Num Value Kinds:
+// ICTEXT: 2
+// ICTEXT: # ValueKind = IPVK_IndirectCallTarget:
+// ICTEXT: 0
+// ICTEXT: # NumValueSites:
+// ICTEXT: 2
+// ICTEXT: 2
+// ICTEXT: test.cpp;_ZN12_GLOBAL__N_18Derived25func1Eii:750
+// ICTEXT: _ZN8Derived15func1Eii:250
+// ICTEXT: 2
+// ICTEXT: test.cpp;_ZN12_GLOBAL__N_18Derived25func2Eii:750
+// ICTEXT: _ZN8Derived15func2Eii:250
+// ICTEXT: # ValueKind = IPVK_VTableTarget:
+// ICTEXT: 2
+// ICTEXT: # NumValueSites:
+// ICTEXT: 2
+// ICTEXT: 2
+// ICTEXT: test.cpp;_ZTVN12_GLOBAL__N_18Derived2E:750
+// ICTEXT: _ZTV8Derived1:250
+// ICTEXT: 2
+// ICTEXT: test.cpp;_ZTVN12_GLOBAL__N_18Derived2E:750
+// ICTEXT: _ZTV8Derived1:250
+
+//--- test.cpp
+#include <cstdio>
+#include <cstdlib>
+class Base {
+public:
+  virtual int func1(int a, int b) = 0;
+  virtual int func2(int a, int b) = 0;
+};
+class Derived1 : public Base {
+public:
+  int func1(int a, int b) override { return a + b; }
+
+  int func2(int a, int b) override { return a * b; }
+};
+namespace {
+class Derived2 : public Base {
+public:
+  int func1(int a, int b) override { return a - b; }
+
+  int func2(int a, int b) override { return a * (a - b); }
+};
+} // namespace
+__attribute__((noinline)) Base *createType(int a) {
+  Base *base = nullptr;
+  if (a % 4 == 0)
+    base = new Derived1();
+  else
+    base = new Derived2();
+  return base;
+}
+int main(int argc, char **argv) {
+  int sum = 0;
+  for (int i = 0; i < 1000; i++) {
+    int a = rand();
+    int b = rand();
+    Base *ptr = createType(i);
+    sum += ptr->func1(a, b) + ptr->func2(b, a);
+  }
+  printf("sum is %d\n", sum);
+  return 0;
+}

llvm/include/llvm/Analysis/IndirectCallVisitor.h

@@ -16,23 +16,75 @@
 #include <vector>
 
 namespace llvm {
-// Visitor class that finds all indirect call.
+// Visitor class that finds indirect calls or instructions that gives vtable
+// value, depending on Type.
 struct PGOIndirectCallVisitor : public InstVisitor<PGOIndirectCallVisitor> {
+  enum class InstructionType {
+    kIndirectCall = 0,
+    kVTableVal = 1,
+  };
   std::vector<CallBase *> IndirectCalls;
-  PGOIndirectCallVisitor() = default;
+  std::vector<Instruction *> ProfiledAddresses;
+  PGOIndirectCallVisitor(InstructionType Type) : Type(Type) {}
 
   void visitCallBase(CallBase &Call) {
-    if (Call.isIndirectCall())
+    if (!Call.isIndirectCall())
+      return;
+
+    if (Type == InstructionType::kIndirectCall) {
       IndirectCalls.push_back(&Call);
+      return;
+    }
+
+    assert(Type == InstructionType::kVTableVal && "Control flow guaranteed");
+
+    LoadInst *LI = dyn_cast<LoadInst>(Call.getCalledOperand());
+    // The code pattern to look for
+    //
+    // %vtable = load ptr, ptr %b
+    // %vfn = getelementptr inbounds ptr, ptr %vtable, i64 1
+    // %2 = load ptr, ptr %vfn
+    // %call = tail call i32 %2(ptr %b)
+    //
+    // %vtable is the vtable address value to profile, and
+    // %2 is the indirect call target address to profile.
+    if (LI != nullptr) {
+      Value *Ptr = LI->getPointerOperand();
+      Value *VTablePtr = Ptr->stripInBoundsConstantOffsets();
+      // This is a heuristic to find address feeding instructions.
+      // FIXME: Add support in the frontend so LLVM type intrinsics are
+      // emitted without LTO. This way, added intrinsics could filter
+      // non-vtable instructions and reduce instrumentation overhead.
+      // Since a non-vtable profiled address is not within the address
+      // range of vtable objects, it's stored as zero in indexed profiles.
+      // A pass that looks up symbol with an zero hash will (almost) always
+      // find nullptr and skip the actual transformation (e.g., comparison
+      // of symbols). So the performance overhead from non-vtable profiled
+      // address is negligible if exists at all. Comparing loaded address
+      // with symbol address guarantees correctness.
+      if (VTablePtr != nullptr && isa<Instruction>(VTablePtr))
+        ProfiledAddresses.push_back(cast<Instruction>(VTablePtr));
+    }
   }
+
+private:
+  InstructionType Type;
 };
 
-// Helper function that finds all indirect call sites.
 inline std::vector<CallBase *> findIndirectCalls(Function &F) {
-  PGOIndirectCallVisitor ICV;
+  PGOIndirectCallVisitor ICV(
+      PGOIndirectCallVisitor::InstructionType::kIndirectCall);
   ICV.visit(F);
   return ICV.IndirectCalls;
 }
+
+inline std::vector<Instruction *> findVTableAddrs(Function &F) {
+  PGOIndirectCallVisitor ICV(
+      PGOIndirectCallVisitor::InstructionType::kVTableVal);
+  ICV.visit(F);
+  return ICV.ProfiledAddresses;
+}
+
 } // namespace llvm
 
 #endif