[clang] [RISCV] Merging RISCVToolChain and BareMetal toolchains (PR #118809)

[Kito Cheng via cfe-commits]

================
@@ -519,9 +650,24 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Arch == llvm::Triple::aarch64_be ? "-EB" : "-EL");
   }
 
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
-                   options::OPT_r)) {
-    CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath("crt0.o")));
+  bool WantCRTs =
+      !Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles);
+
+  const char *crtbegin, *crtend;
+  if (WantCRTs) {
+    if (!Args.hasArg(options::OPT_r))
+      CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath("crt0.o")));
+    auto RuntimeLib = TC.GetRuntimeLibType(Args);
+    if (RuntimeLib == ToolChain::RLT_Libgcc) {
+      crtbegin = "crtbegin.o";
+      crtend = "crtend.o";
+    } else {
+      assert(RuntimeLib == ToolChain::RLT_CompilerRT);
+      crtbegin =
+          TC.getCompilerRTArgString(Args, "crtbegin", ToolChain::FT_Object);
+      crtend = TC.getCompilerRTArgString(Args, "crtend", ToolChain::FT_Object);
+    }
+    CmdArgs.push_back(Args.MakeArgString(TC.GetFilePath(crtbegin)));
   }
 
   Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group,
----------------
kito-cheng wrote:

Add `options::OPT_u` here:
e.g.
```suggestion
  Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group, options::OPT_u,
```

https://github.com/llvm/llvm-project/pull/118809