[CodeGen] emit CG profile for COFF object file

Differential Revision: https://reviews.llvm.org/D87811

include/llvm/CodeGen/TargetLoweringObjectFileImpl.h

@@ -143,6 +143,7 @@ public:
 
 class TargetLoweringObjectFileCOFF : public TargetLoweringObjectFile {
   mutable unsigned NextUniqueID = 0;
+  const TargetMachine *TM = nullptr;
 
 public:
   ~TargetLoweringObjectFileCOFF() override = default;

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -1599,18 +1599,62 @@ void TargetLoweringObjectFileCOFF::emitModuleMetadata(MCStreamer &Streamer,
   StringRef Section;
 
   GetObjCImageInfo(M, Version, Flags, Section);
-  if (Section.empty())
-    return;
+  if (!Section.empty()) {
+    auto &C = getContext();
+    auto *S = C.getCOFFSection(Section,
+                               COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+                                   COFF::IMAGE_SCN_MEM_READ,
+                               SectionKind::getReadOnly());
+    Streamer.SwitchSection(S);
+    Streamer.emitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
+    Streamer.emitInt32(Version);
+    Streamer.emitInt32(Flags);
+    Streamer.AddBlankLine();
+  }
 
   auto &C = getContext();
-  auto *S = C.getCOFFSection(
-      Section, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
-      SectionKind::getReadOnly());
-  Streamer.SwitchSection(S);
-  Streamer.emitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
-  Streamer.emitInt32(Version);
-  Streamer.emitInt32(Flags);
-  Streamer.AddBlankLine();
+  SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
+  M.getModuleFlagsMetadata(ModuleFlags);
+
+  MDNode *CFGProfile = nullptr;
+
+  for (const auto &MFE : ModuleFlags) {
+    StringRef Key = MFE.Key->getString();
+    if (Key == "CG Profile") {
+      CFGProfile = cast<MDNode>(MFE.Val);
+      break;
+    }
+  }
+
+  if (!CFGProfile)
+    return;
+
+  auto GetSym = [this](const MDOperand &MDO) -> MCSymbol * {
+    if (!MDO)
+      return nullptr;
+    auto V = cast<ValueAsMetadata>(MDO);
+    const Function *F = cast<Function>(V->getValue());
+    if (F->hasDLLImportStorageClass())
+      return nullptr;
+    return TM->getSymbol(F);
+  };
+
+  for (const auto &Edge : CFGProfile->operands()) {
+    MDNode *E = cast<MDNode>(Edge);
+    const MCSymbol *From = GetSym(E->getOperand(0));
+    const MCSymbol *To = GetSym(E->getOperand(1));
+    // Skip null functions. This can happen if functions are dead stripped after
+    // the CGProfile pass has been run.
+    if (!From || !To)
+      continue;
+    uint64_t Count = cast<ConstantAsMetadata>(E->getOperand(2))
+                         ->getValue()
+                         ->getUniqueInteger()
+                         .getZExtValue();
+    Streamer.emitCGProfileEntry(
+        MCSymbolRefExpr::create(From, MCSymbolRefExpr::VK_None, C),
+        MCSymbolRefExpr::create(To, MCSymbolRefExpr::VK_None, C), Count);
+  }
 }
 
 void TargetLoweringObjectFileCOFF::emitLinkerDirectives(
@@ -1675,6 +1719,7 @@ void TargetLoweringObjectFileCOFF::emitLinkerDirectives(
 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
                                               const TargetMachine &TM) {
   TargetLoweringObjectFile::Initialize(Ctx, TM);
+  this->TM = &TM;
   const Triple &T = TM.getTargetTriple();
   if (T.isWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
     StaticCtorSection =

test/MC/COFF/cgprofile.ll

@@ -0,0 +1,51 @@
+; RUN: llc -filetype=asm %s -o - -mtriple x86_64-pc-windows-msvc | FileCheck %s
+; RUN: llc -filetype=obj %s -o %t -mtriple x86_64-pc-windows-msvc
+; RUN: llvm-readobj --cg-profile %t | FileCheck %s --check-prefix=OBJ
+
+declare void @b()
+
+define void @a() {
+  call void @b()
+  ret void
+}
+
+define void @freq(i1 %cond) {
+  br i1 %cond, label %A, label %B
+A:
+  call void @a();
+  ret void
+B:
+  call void @b();
+  ret void
+}
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 5, !"CG Profile", !1}
+!1 = !{!2, !3, !4, !5}
+!2 = !{void ()* @a, void ()* @b, i64 32}
+!3 = !{void (i1)* @freq, void ()* @a, i64 11}
+!4 = !{void (i1)* @freq, void ()* @b, i64 20}
+!5 = !{void (i1)* @freq, null, i64 20}
+
+; CHECK: .cg_profile a, b, 32
+; CHECK: .cg_profile freq, a, 11
+; CHECK: .cg_profile freq, b, 20
+
+; OBJ: CGProfile [
+; OBJ:  CGProfileEntry {
+; OBJ:    From: a
+; OBJ:    To: b
+; OBJ:    Weight: 32
+; OBJ:  }
+; OBJ:  CGProfileEntry {
+; OBJ:    From: freq
+; OBJ:    To: a
+; OBJ:    Weight: 11
+; OBJ:  }
+; OBJ:  CGProfileEntry {
+; OBJ:    From: freq
+; OBJ:    To: b
+; OBJ:    Weight: 20
+; OBJ:  }
+; OBJ:]