[llvm-config] Support MSVS layout

[broadwaylamb]

Summary

When using a Visual Studio generator in CMake, the llvm-config
executable is placed in the ${LLVM_OBJ_ROOT}/<build-mode>/bin
directory, which wasn't recognized by the llvm-config tool.

This led to llvm-config returning the wrong path for --cmakedir.
This is fixed here.

[broadwaylamb]

Could anyone verify this patch?

[broadwaylamb]

ping

llvm/tools/llvm-config/llvm-config.cpp

int main(int argc, char **argv) {
   bool PrintSystemLibs = false, PrintSharedMode = false;
   bool HasAnyOption = false;
 
   // llvm-config is designed to support being run both from a development tree
   // and from an installed path. We try and auto-detect which case we are in so
   // that we can report the correct information when run from a development
   // tree.
   bool IsInDevelopmentTree;
-  enum { CMakeStyle, CMakeBuildModeStyle } DevelopmentTreeLayout;
+
+  enum {
+    // llvm-config is in ${LLVM_OBJ_ROOT}/bin/
+    CMakeStyle,
+
+    // llvm-config is in ${LLVM_OBJ_ROOT}/bin/<build-mode>
+    CMakeBuildModeStyle,
+
+    // llvm-config is in ${LLVM_OBJ_ROOT}/<build-mode>/bin
+    CMakeReverseBuildModeStyle
+  } DevelopmentTreeLayout;
+
   llvm::SmallString<256> CurrentPath(GetExecutablePath(argv[0]));
   std::string CurrentExecPrefix;
   std::string ActiveObjRoot;
 
   // If CMAKE_CFG_INTDIR is given, honor it as build mode.
   char const *build_mode = LLVM_BUILDMODE;
 #if defined(CMAKE_CFG_INTDIR)
   if (!(CMAKE_CFG_INTDIR[0] == '.' && CMAKE_CFG_INTDIR[1] == '\0'))
if (sys::fs::equivalent(CurrentExecPrefix, LLVM_OBJ_ROOT)) {
     IsInDevelopmentTree = true;
     DevelopmentTreeLayout = CMakeStyle;
     ActiveObjRoot = LLVM_OBJ_ROOT;
   } else if (sys::fs::equivalent(sys::path::parent_path(CurrentExecPrefix),
                                  LLVM_OBJ_ROOT)) {
     IsInDevelopmentTree = true;
     DevelopmentTreeLayout = CMakeBuildModeStyle;
     ActiveObjRoot = LLVM_OBJ_ROOT;
+  } else if (sys::fs::equivalent(CurrentExecPrefix,
+                                 Twine(LLVM_OBJ_ROOT) + "/" + build_mode)) {
+    IsInDevelopmentTree = true;
+    DevelopmentTreeLayout = CMakeReverseBuildModeStyle;
+    ActiveObjRoot = LLVM_OBJ_ROOT;
   } else {
     IsInDevelopmentTree = false;
     DevelopmentTreeLayout = CMakeStyle; // Initialized to avoid warnings.
   }
 
   // Compute various directory locations based on the derived location
   // information.
   std::string ActivePrefix, ActiveBinDir, ActiveIncludeDir, ActiveLibDir,
case CMakeBuildModeStyle:
       ActivePrefix = ActiveObjRoot;
       ActiveBinDir = ActiveObjRoot + "/" + build_mode + "/bin";
       ActiveLibDir =
           ActiveObjRoot + "/" + build_mode + "/lib" + LLVM_LIBDIR_SUFFIX;
       // The CMake directory isn't separated by build mode.
       ActiveCMakeDir =
           ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX + "/cmake/llvm";
       break;
+    case CMakeReverseBuildModeStyle:
+      ActiveBinDir = ActiveObjRoot + "/" + build_mode + "/bin";
+      ActiveLibDir =
+          ActiveObjRoot + "/" + build_mode + "/lib" + LLVM_LIBDIR_SUFFIX;
+      ActiveCMakeDir = ActiveObjRoot + "/lib/cmake/llvm";
+      break;
     }
 
     // We need to include files from both the source and object trees.
     ActiveIncludeOption =
         ("-I" + ActiveIncludeDir + " " + "-I" + ActiveObjRoot + "/include");
   } else {
     ActivePrefix = CurrentExecPrefix;
     ActiveIncludeDir = ActivePrefix + "/include";