[llvm-driver] Check more specific tools first

[abrachet]

Summary

We allow tools to be called {tool}-{suffix} to support tools being
called something like clang-17. Many clang tools follow this pattern
too for example, clang-scan-deps. It is pure luck wether clang or
clang-scan-deps will appear first in the LLVMDriverTools.def file. If
the former appears first, clang-scan-deps will match against clang,
which is not preferable. Instead we can control the order that tools
are checked so that we always look at more specific tool names first.

[MaskRay]

llvm/tools/llvm-driver/llvm-driver.cpp

32

This leaves a dynamic initialization. It'd be better to keep LLVMDriverTools.def and reverse iterate ToolMap.

32

I mean "keep LLVMDriverTools.def sorted".

llvm/tools/llvm-driver/llvm-driver.cpp

 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LLVMDriver.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/WithColor.h"
 
+#include <map>
+
 using namespace llvm;
 
 #define LLVM_DRIVER_TOOL(tool, entry)                                          \
   int entry##_main(int argc, char **argv, const llvm::ToolContext &);
 #include "LLVMDriverTools.def"
 
 constexpr char subcommands[] =
 #define LLVM_DRIVER_TOOL(tool, entry) "  " tool "\n"
 #include "LLVMDriverTools.def"
     ;
 
+using ToolEntry = int(int, char **, const llvm::ToolContext &);
+std::map<StringRef, ToolEntry &, std::greater<StringRef>> ToolMap{
+#define LLVM_DRIVER_TOOL(tool, entry) {tool, entry##_main},
+#include "LLVMDriverTools.def"
+};
+
 static void printHelpMessage() {
   llvm::outs() << "OVERVIEW: llvm toolchain driver\n\n"
                << "USAGE: llvm [subcommand] [options]\n\n"
                << "SUBCOMMANDS:\n\n"
                << subcommands
                << "\n  Type \"llvm <subcommand> --help\" to get more help on a "
                   "specific subcommand\n\n"
                << "OPTIONS:\n\n  --help - Display this message";
static int findTool(int Argc, char **Argv, const char *Argv0) {
   };
 
   auto MakeDriverArgs = [=]() -> llvm::ToolContext {
     if (ToolName != Argv0)
       return {Argv0, ToolName.data(), true};
     return {Argv0, sys::path::filename(Argv0).data(), false};
   };
 
-#define LLVM_DRIVER_TOOL(tool, entry)                                          \
-  if (Is(tool))                                                                \
-    return entry##_main(Argc, Argv, MakeDriverArgs());
-#include "LLVMDriverTools.def"
+  for (auto &[tool, entry] : ToolMap)
+    if (Is(tool))
+      return entry(Argc, Argv, MakeDriverArgs());
 
   if (Is("llvm") || Argv0 == Argv[0])
     return findTool(Argc - 1, Argv + 1, Argv0);
 
   printHelpMessage();
   return 1;
 }
 
 int main(int Argc, char **Argv) { return findTool(Argc, Argv, Argv[0]); }