[lldb][RISCV] doubles support in lldb expressions

Function calls support in LLDB expressions for RISCV: 4 of 5

This patch adds desired feature flags in MCJIT compiler to enable
hard-float instructions if target supports them and allows to use floats
and doubles in lldb expressions.

Author: dlav-sc

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -43,6 +43,7 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/TargetSelect.h"
+#include "llvm/TargetParser/Triple.h"
 
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
@@ -407,24 +408,50 @@ static void SetupDefaultClangDiagnostics(CompilerInstance &compiler) {
 /// \return
 ///     A string representing target ABI for the current architecture.
 static std::string GetClangTargetABI(const ArchSpec &target_arch) {
-  std::string abi;
-
   if (target_arch.IsMIPS()) {
     switch (target_arch.GetFlags() & ArchSpec::eMIPSABI_mask) {
     case ArchSpec::eMIPSABI_N64:
-      abi = "n64";
-      break;
+      return "n64";
     case ArchSpec::eMIPSABI_N32:
-      abi = "n32";
-      break;
+      return "n32";
     case ArchSpec::eMIPSABI_O32:
-      abi = "o32";
-      break;
+      return "o32";
     default:
-      break;
+      return {};
     }
   }
-  return abi;
+
+  if (target_arch.GetTriple().isRISCV64()) {
+    switch (target_arch.GetFlags() & ArchSpec::eRISCV_float_abi_mask) {
+    case ArchSpec::eRISCV_float_abi_soft:
+      return "lp64";
+    case ArchSpec::eRISCV_float_abi_single:
+      return "lp64f";
+    case ArchSpec::eRISCV_float_abi_double:
+      return "lp64d";
+    case ArchSpec::eRISCV_float_abi_quad:
+      return "lp64q";
+    default:
+      return {};
+    }
+  }
+
+  if (target_arch.GetTriple().isRISCV32()) {
+    switch (target_arch.GetFlags() & ArchSpec::eRISCV_float_abi_mask) {
+    case ArchSpec::eRISCV_float_abi_soft:
+      return "ilp32";
+    case ArchSpec::eRISCV_float_abi_single:
+      return "ilp32f";
+    case ArchSpec::eRISCV_float_abi_double:
+      return "ilp32d";
+    case ArchSpec::eRISCV_float_abi_soft | ArchSpec::eRISCV_rve:
+      return "ilp32e";
+    default:
+      return {};
+    }
+  }
+
+  return {};
 }
 
 static void SetupTargetOpts(CompilerInstance &compiler,
@@ -471,6 +498,18 @@ static void SetupTargetOpts(CompilerInstance &compiler,
   // Set the target ABI
   if (std::string abi = GetClangTargetABI(target_arch); !abi.empty())
     compiler.getTargetOpts().ABI = std::move(abi);
+
+  if ((target_machine == llvm::Triple::riscv64 &&
+       compiler.getTargetOpts().ABI == "lp64f") ||
+      (target_machine == llvm::Triple::riscv32 &&
+       compiler.getTargetOpts().ABI == "ilp32f"))
+    compiler.getTargetOpts().FeaturesAsWritten.emplace_back("+f");
+
+  if ((target_machine == llvm::Triple::riscv64 &&
+       compiler.getTargetOpts().ABI == "lp64d") ||
+      (target_machine == llvm::Triple::riscv32 &&
+       compiler.getTargetOpts().ABI == "ilp32d"))
+    compiler.getTargetOpts().FeaturesAsWritten.emplace_back("+d");
 }
 
 static void SetupLangOpts(CompilerInstance &compiler,
@@ -722,7 +761,7 @@ ClangExpressionParser::ClangExpressionParser(
   m_compiler->getCodeGenOpts().EmitDeclMetadata = true;
   m_compiler->getCodeGenOpts().InstrumentFunctions = false;
   m_compiler->getCodeGenOpts().setFramePointer(
-                                    CodeGenOptions::FramePointerKind::All);
+      CodeGenOptions::FramePointerKind::All);
   if (generate_debug_info)
     m_compiler->getCodeGenOpts().setDebugInfo(codegenoptions::FullDebugInfo);
   else
@@ -736,7 +775,7 @@ ClangExpressionParser::ClangExpressionParser(
   // FIXME: We shouldn't need to do this, the target should be immutable once
   // created. This complexity should be lifted elsewhere.
   m_compiler->getTarget().adjust(m_compiler->getDiagnostics(),
-		                 m_compiler->getLangOpts());
+                                 m_compiler->getLangOpts());
 
   // 5. Set up the diagnostic buffer for reporting errors
 
@@ -1156,8 +1195,7 @@ ClangExpressionParser::ParseInternal(DiagnosticManager &diagnostic_manager,
           if (auto fileEntry = m_compiler->getFileManager().getOptionalFileRef(
                   result_path)) {
             source_mgr.setMainFileID(source_mgr.createFileID(
-                *fileEntry,
-                SourceLocation(), SrcMgr::C_User));
+                *fileEntry, SourceLocation(), SrcMgr::C_User));
             created_main_file = true;
           }
         }
@@ -1504,7 +1542,8 @@ lldb_private::Status ClangExpressionParser::DoPrepareForExecution(
 
           DiagnosticManager install_diags;
           if (Error Err = dynamic_checkers->Install(install_diags, exe_ctx)) {
-            std::string ErrMsg = "couldn't install checkers: " + toString(std::move(Err));
+            std::string ErrMsg =
+                "couldn't install checkers: " + toString(std::move(Err));
             if (install_diags.Diagnostics().size())
               ErrMsg = ErrMsg + "\n" + install_diags.GetString().c_str();
             err = Status(ErrMsg);