[clang] [llvm] [PseudoProbe] Support emitting to COFF object (PR #123870)

[Wei Xiao via llvm-commits]

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@@ -1221,44 +1231,68 @@ MCObjectFileInfo::getKCFITrapSection(const MCSection &TextSec) const {
 
 MCSection *
 MCObjectFileInfo::getPseudoProbeSection(const MCSection &TextSec) const {
-  if (Ctx->getObjectFileType() != MCContext::IsELF)
-    return PseudoProbeSection;
-
-  const auto &ElfSec = static_cast<const MCSectionELF &>(TextSec);
-  unsigned Flags = ELF::SHF_LINK_ORDER;
-  StringRef GroupName;
-  if (const MCSymbol *Group = ElfSec.getGroup()) {
-    GroupName = Group->getName();
-    Flags |= ELF::SHF_GROUP;
+  auto ObjFileType = Ctx->getObjectFileType();
+  if (ObjFileType == MCContext::IsELF) {
+    const auto &ElfSec = static_cast<const MCSectionELF &>(TextSec);
+    unsigned Flags = ELF::SHF_LINK_ORDER;
+    StringRef GroupName;
+    if (const MCSymbol *Group = ElfSec.getGroup()) {
+      GroupName = Group->getName();
+      Flags |= ELF::SHF_GROUP;
+    }
+    return Ctx->getELFSection(
+        PseudoProbeSection->getName(), ELF::SHT_PROGBITS, Flags, 0, GroupName,
+        true, ElfSec.getUniqueID(),
+        static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
+  } else if (ObjFileType == MCContext::IsCOFF) {
+    StringRef COMDATSymName = "";
+    int Selection = 0;
+    unsigned Characteristics =
+        static_cast<MCSectionCOFF *>(PseudoProbeSection)->getCharacteristics();
+    const auto &COFFSec = static_cast<const MCSectionCOFF &>(TextSec);
+    if (const MCSymbol *COMDATSym = COFFSec.getCOMDATSymbol()) {
+      // Associate .pseudo_probe to its function section.
+      COMDATSymName = COMDATSym->getName();
+      Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
+      Selection = COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
+    }
+    return Ctx->getCOFFSection(PseudoProbeSection->getName(), Characteristics,
+                               COMDATSymName, Selection, COFFSec.getUniqueID());
   }
 
-  return Ctx->getELFSection(
-      PseudoProbeSection->getName(), ELF::SHT_PROGBITS, Flags, 0, GroupName,
-      true, ElfSec.getUniqueID(),
-      static_cast<const MCSymbolELF *>(TextSec.getBeginSymbol()));
+  return PseudoProbeSection;
 }
 
 MCSection *
 MCObjectFileInfo::getPseudoProbeDescSection(StringRef FuncName) const {
-  if (Ctx->getObjectFileType() == MCContext::IsELF) {
-    // Create a separate comdat group for each function's descriptor in order
-    // for the linker to deduplicate. The duplication, must be from different
-    // tranlation unit, can come from:
-    //  1. Inline functions defined in header files;
-    //  2. ThinLTO imported funcions;
-    //  3. Weak-linkage definitions.
-    // Use a concatenation of the section name and the function name as the
-    // group name so that descriptor-only groups won't be folded with groups of
-    // code.
-    if (Ctx->getTargetTriple().supportsCOMDAT() && !FuncName.empty()) {
-      auto *S = static_cast<MCSectionELF *>(PseudoProbeDescSection);
-      auto Flags = S->getFlags() | ELF::SHF_GROUP;
-      return Ctx->getELFSection(S->getName(), S->getType(), Flags,
-                                S->getEntrySize(),
-                                S->getName() + "_" + FuncName,
-                                /*IsComdat=*/true);
-    }
+  if (!Ctx->getTargetTriple().supportsCOMDAT() || FuncName.empty())
+    return PseudoProbeDescSection;
+
+  // Create a separate comdat group for each function's descriptor in order
+  // for the linker to deduplicate. The duplication, must be from different
+  // tranlation unit, can come from:
+  //  1. Inline functions defined in header files;
+  //  2. ThinLTO imported funcions;
+  //  3. Weak-linkage definitions.
+  // Use a concatenation of the section name and the function name as the
+  // group name so that descriptor-only groups won't be folded with groups of
+  // code.
+  auto ObjFileType = Ctx->getObjectFileType();
+  if (ObjFileType == MCContext::IsELF) {
+    auto *S = static_cast<MCSectionELF *>(PseudoProbeDescSection);
+    auto Flags = S->getFlags() | ELF::SHF_GROUP;
+    return Ctx->getELFSection(S->getName(), S->getType(), Flags,
+                              S->getEntrySize(), S->getName() + "_" + FuncName,
+                              /*IsComdat=*/true);
+  } else if (ObjFileType == MCContext::IsCOFF) {
+    auto *S = static_cast<MCSectionCOFF *>(PseudoProbeDescSection);
+    unsigned Characteristics =
+        S->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT;
+    std::string COMDATSymName = (S->getName() + "_" + FuncName).str();
+    return Ctx->getCOFFSection(S->getName(), Characteristics, COMDATSymName,
+                               COFF::IMAGE_COMDAT_SELECT_ANY);
----------------
williamweixiao wrote:

IMAGE_COMDAT_SELECT_EXACT_MATCH?

https://github.com/llvm/llvm-project/pull/123870