Add OxCaml runlength demangling

Author: shym

lldb/include/lldb/Core/Mangled.h

@@ -43,6 +43,7 @@ class Mangled {
     eManglingSchemeNone = 0,
     eManglingSchemeMSVC,
     eManglingSchemeItanium,
+    eManglingSchemeOxCaml,
     eManglingSchemeRustV0,
     eManglingSchemeD
   };

lldb/source/Core/Mangled.cpp

@@ -44,6 +44,9 @@ Mangled::ManglingScheme Mangled::GetManglingScheme(llvm::StringRef const name) {
   if (name.startswith("?"))
     return Mangled::eManglingSchemeMSVC;
 
+  if (name.startswith("_O"))
+    return Mangled::eManglingSchemeOxCaml;
+
   if (name.startswith("_R"))
     return Mangled::eManglingSchemeRustV0;
 
@@ -167,6 +170,19 @@ static char *GetItaniumDemangledStr(const char *M) {
   return demangled_cstr;
 }
 
+static char *GetOxCamlDemangledStr(const char *M) {
+  char *demangled_cstr = llvm::oxcamlDemangle(M);
+
+  if (Log *log = GetLog(LLDBLog::Demangle)) {
+    if (demangled_cstr && demangled_cstr[0])
+      LLDB_LOG(log, "demangled oxcaml: {0} -> \"{1}\"", M, demangled_cstr);
+    else
+      LLDB_LOG(log, "demangled oxcaml: {0} -> error: failed to demangle", M);
+  }
+
+  return demangled_cstr;
+}
+
 static char *GetRustV0DemangledStr(const char *M) {
   char *demangled_cstr = llvm::rustDemangle(M);
 
@@ -242,6 +258,7 @@ bool Mangled::GetRichManglingInfo(RichManglingContext &context,
     }
   }
 
+  case eManglingSchemeOxCaml:
   case eManglingSchemeRustV0:
   case eManglingSchemeD:
     // Rich demangling scheme is not supported
@@ -275,6 +292,9 @@ ConstString Mangled::GetDemangledName() const {
         demangled_name = GetItaniumDemangledStr(mangled_name);
         break;
       }
+      case eManglingSchemeOxCaml:
+        demangled_name = GetOxCamlDemangledStr(mangled_name);
+        break;
       case eManglingSchemeRustV0:
         demangled_name = GetRustV0DemangledStr(mangled_name);
         break;

lldb/source/Symbol/Symtab.cpp

@@ -255,6 +255,7 @@ static bool lldb_skip_name(llvm::StringRef mangled,
 
   // No filters for this scheme yet. Include all names in indexing.
   case Mangled::eManglingSchemeMSVC:
+  case Mangled::eManglingSchemeOxCaml:
   case Mangled::eManglingSchemeRustV0:
   case Mangled::eManglingSchemeD:
     return false;

llvm/include/llvm/Demangle/Demangle.h

@@ -57,6 +57,9 @@ char *microsoftDemangle(const char *mangled_name, size_t *n_read, char *buf,
                         size_t *n_buf, int *status,
                         MSDemangleFlags Flags = MSDF_None);
 
+// Demangles an OxCaml mangled symbol
+char *oxcamlDemangle(const char *MangledName);
+
 // Demangles a Rust v0 mangled symbol.
 char *rustDemangle(const char *MangledName);
 

llvm/lib/Demangle/CMakeLists.txt

@@ -3,6 +3,7 @@ add_llvm_component_library(LLVMDemangle
   ItaniumDemangle.cpp
   MicrosoftDemangle.cpp
   MicrosoftDemangleNodes.cpp
+  OxCamlDemangle.cpp
   RustDemangle.cpp
   DLangDemangle.cpp
 

llvm/lib/Demangle/Demangle.cpp

@@ -19,6 +19,9 @@ static bool isItaniumEncoding(const char *S) {
   return std::strncmp(S, "_Z", 2) == 0 || std::strncmp(S, "___Z", 4) == 0;
 }
 
+static bool isOxCamlEncoding(const std::string &S) {
+    return S.size() >= 2 && S[0] == '_' && S[1] == 'O'; }
+
 static bool isRustEncoding(const char *S) { return S[0] == '_' && S[1] == 'R'; }
 
 static bool isDLangEncoding(const std::string &MangledName) {
@@ -54,6 +57,8 @@ bool llvm::nonMicrosoftDemangle(const char *MangledName, std::string &Result) {
     Demangled = rustDemangle(MangledName);
   else if (isDLangEncoding(MangledName))
     Demangled = dlangDemangle(MangledName);
+  else if (isOxCamlEncoding(MangledName))
+    Demangled = oxcamlDemangle(MangledName);
 
   if (!Demangled)
     return false;

llvm/lib/Demangle/OxCamlDemangle.cpp

@@ -0,0 +1,256 @@
+//===--- OxCamlDemangle.cpp -------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a demangler for the new mangling scheme devised for OxCaml
+//
+//===----------------------------------------------------------------------===//
+
+#include <cassert>
+
+#include "llvm/Demangle/Demangle.h"
+#include "llvm/Demangle/StringView.h"
+#include "llvm/Demangle/Utility.h"
+
+using llvm::itanium_demangle::OutputBuffer;
+using llvm::itanium_demangle::StringView;
+
+#define ERROR (~((unsigned)0))
+
+static unsigned ConsumeUnsignedDecimal(StringView& sv) {
+  unsigned res = 0, i = 0;
+  while(sv[i] >= '0' && sv[i] <= '9') {
+    res = res * 10 + (sv[i] - '0');
+    i++;
+  }
+  sv = sv.dropFront(i);
+  if(i == 0)
+    return ERROR;
+  return res;
+}
+
+static unsigned ConsumeUnsigned26(StringView& sv) {
+  unsigned res = 0, i = 0;
+  while(sv[i] >= 'A' && sv[i] <= 'Z') {
+    res = res * 26 + (sv[i] - 'A');
+    i++;
+  }
+  sv = sv.dropFront(i);
+  if(i == 0)
+    return ERROR;
+  return res;
+}
+
+static bool islowerhex(char c) {
+  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
+}
+
+static unsigned lowerhex(char c) {
+  if(c >= '0' && c <= '9')
+    return c - '0';
+  else {
+    assert(c >= 'a' && c <= 'f');
+    return c - 'a' + 10;
+  }
+}
+
+// Decode unicode-escaped identifier (format: u<len><coded>_<raw>)
+// Returns true on success, false on error
+static bool DecodeUnicodeEscaped(StringView& Mangled, OutputBuffer& Demangled) {
+  unsigned len = ConsumeUnsignedDecimal(Mangled);
+  if(len == ERROR || len <= 0 || len > Mangled.size())
+    return false;
+
+  size_t split = Mangled.find('_');
+  if(split >= len)
+    return false;
+
+  StringView coded = Mangled.substr(0, split);
+  StringView raw = Mangled.substr(split+1, len-split-1);
+
+  while(!coded.empty()) {
+    unsigned chunklen = ConsumeUnsigned26(coded);
+    if(chunklen == ERROR || chunklen > raw.size())
+      return false;
+    Demangled << raw.substr(0, chunklen);
+    raw = raw.dropFront(chunklen);
+
+    unsigned i;
+    for(i = 0; i+1 < coded.size() && islowerhex(coded[i]); i+=2) {
+      if(!islowerhex(coded[i+1]))
+        return false;
+      char c = (char)(lowerhex(coded[i]) << 4 | lowerhex(coded[i+1]));
+      Demangled << c;
+    }
+    coded = coded.dropFront(i);
+  }
+
+  if(!raw.empty())
+    Demangled << raw;
+
+  Mangled = Mangled.dropFront(len);
+  return true;
+}
+
+// Decode identifier (either plain or unicode-escaped)
+// Handles: <len><text> or u<len><coded>_<raw>
+// Returns true on success, false on error
+static bool DecodeIdentifier(StringView& Mangled, OutputBuffer& Demangled) {
+  if(Mangled.consumeFront('u')) {
+    // Unicode-escaped identifier
+    return DecodeUnicodeEscaped(Mangled, Demangled);
+  } else {
+    // Plain identifier with length prefix
+    unsigned len = ConsumeUnsignedDecimal(Mangled);
+    if(len == ERROR || len <= 0 || len > Mangled.size())
+      return false;
+    Demangled << Mangled.substr(0, len);
+    Mangled = Mangled.dropFront(len);
+    return true;
+  }
+}
+
+// Decode anonymous location (format: filename_line_col)
+// Anonymous functions/modules are encoded as: fn(filename:line:col)
+// Returns true on success, false on error
+static bool DecodeAnonymousLocation(StringView& Mangled, OutputBuffer& Demangled) {
+  // Allocate temporary buffer based on remaining mangled string size
+  // The decoded identifier will be at most the size of the remaining mangled string
+  size_t buffer_size = Mangled.size();
+  if(buffer_size == 0)
+    return false;
+
+  char *temp_buf = static_cast<char *>(std::malloc(buffer_size));
+  if(temp_buf == nullptr)
+    std::terminate();
+
+  OutputBuffer TempDemangled(temp_buf, buffer_size);
+
+  if(!DecodeIdentifier(Mangled, TempDemangled)) {
+    std::free(temp_buf);
+    return false;
+  }
+
+  size_t temp_len = TempDemangled.getCurrentPosition();
+
+  // Parse filename_line_col format by finding the last two underscores
+  size_t first_underscore = 0, second_underscore = 0;
+  int underscore_count = 0;
+
+  for(size_t j = temp_len; j > 0; j--) {
+    if(temp_buf[j-1] == '_') {
+      underscore_count++;
+      if(underscore_count == 1)
+        second_underscore = j - 1;
+      else if(underscore_count == 2) {
+        first_underscore = j - 1;
+        break;
+      }
+    }
+  }
+
+  // Output in format fn(filename:line:col)
+  if(underscore_count >= 2) {
+    Demangled << "fn(";
+    for(size_t j = 0; j < first_underscore; j++)
+      Demangled << temp_buf[j];
+    Demangled << ':';
+    for(size_t j = first_underscore + 1; j < second_underscore; j++)
+      Demangled << temp_buf[j];
+    Demangled << ':';
+    for(size_t j = second_underscore + 1; j < temp_len; j++)
+      Demangled << temp_buf[j];
+    Demangled << ')';
+  } else {
+    // Fallback: just output the identifier as-is
+    for(size_t j = 0; j < temp_len; j++)
+      Demangled << temp_buf[j];
+  }
+
+  std::free(temp_buf);
+  return true;
+}
+
+char *llvm::oxcamlDemangle(const char *MangledName) {
+  StringView Mangled(MangledName);
+  if(!Mangled.consumeFront("_O"))
+    return nullptr;
+
+  // Allocate the buffer at a reasonable size, as OutputBuffer allocates 992
+  // bytes when starting from an empty buffer
+  char *DemangledBuffer;
+  DemangledBuffer = static_cast<char *>(std::malloc(Mangled.size()));
+  if (DemangledBuffer == nullptr)
+    std::terminate();
+  OutputBuffer Demangled(DemangledBuffer, Mangled.size());
+
+#define ENDONERROR() do {           \
+  std::free(Demangled.getBuffer()); \
+  return nullptr;                   \
+} while(0)
+
+  // Parse path items
+  while(!Mangled.empty()) {
+      // Check for terminating underscore
+      if(Mangled[0] == '_') {
+          // End of symbol path, rest is unique id
+          break;
+      }
+
+      // Handle each path_item type
+      switch(Mangled[0]) {
+          case 'M':  // Module
+              if(!Demangled.empty())
+                  Demangled << '.';
+              Mangled = Mangled.dropFront(1);
+              if(!DecodeIdentifier(Mangled, Demangled))
+                  ENDONERROR();
+              break;
+
+          case 'F':  // NamedFunction
+              if(!Demangled.empty())
+                  Demangled << '.';
+              Mangled = Mangled.dropFront(1);
+              if(!DecodeIdentifier(Mangled, Demangled))
+                  ENDONERROR();
+              break;
+
+          case 'L':  // AnonymousFunction
+              if(!Demangled.empty())
+                  Demangled << '.';
+              Mangled = Mangled.dropFront(1);
+              if(!DecodeAnonymousLocation(Mangled, Demangled))
+                  ENDONERROR();
+              break;
+
+          case 'S':  // AnonymousModule
+              if(!Demangled.empty())
+                  Demangled << '.';
+              Mangled = Mangled.dropFront(1);
+              if(!DecodeAnonymousLocation(Mangled, Demangled))
+                  ENDONERROR();
+              break;
+
+          case 'P':  // PartialFunction (no dot separator)
+              Mangled = Mangled.dropFront(1);
+              Demangled << "(partially_applied)";
+              break;
+
+          default:
+              // No prefix means Module (legacy compatibility)
+              if(!Demangled.empty())
+                  Demangled << '.';
+              if(!DecodeIdentifier(Mangled, Demangled))
+                  ENDONERROR();
+              break;
+      }
+  }
+
+  Demangled << '\0';
+
+  return Demangled.getBuffer();
+}

llvm/unittests/Demangle/CMakeLists.txt

@@ -10,5 +10,6 @@ add_llvm_unittest(DemangleTests
   OutputBufferTest.cpp
   PartialDemangleTest.cpp
   RustDemangleTest.cpp
+  OxCamlDemangleTest.cpp
   StringViewTest.cpp
 )