[NvlinkWrapper] Use -plugin-opt=mattr= instead of a custom feature (#111712)

Summary:
We don't need a custom flag for this, LLVM had a way to get the features
which are forwarded via `plugin-opt`.

Author: jhuber6

clang/lib/Driver/ToolChains/Cuda.cpp

@@ -634,8 +634,8 @@ void NVPTX::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   std::vector<StringRef> Features;
   getNVPTXTargetFeatures(C.getDriver(), getToolChain().getTriple(), Args,
                          Features);
-  for (StringRef Feature : Features)
-    CmdArgs.append({"--feature", Args.MakeArgString(Feature)});
+  CmdArgs.push_back(
+      Args.MakeArgString("--plugin-opt=mattr=" + llvm::join(Features, ",")));
 
   // Add paths for the default clang library path.
   SmallString<256> DefaultLibPath =

clang/test/Driver/cuda-cross-compiling.c

@@ -104,4 +104,4 @@
 // RUN: %clang -target nvptx64-nvidia-cuda --cuda-feature=+ptx63 -march=sm_52 -### %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=FEATURE %s
 
-// FEATURE: clang-nvlink-wrapper{{.*}}"--feature" "+ptx63"
+// FEATURE: clang-nvlink-wrapper{{.*}}"--plugin-opt=mattr=+ptx63"

clang/tools/clang-nvlink-wrapper/ClangNVLinkWrapper.cpp

@@ -344,7 +344,7 @@ Expected<std::unique_ptr<lto::LTO>> createLTO(const ArgList &Args) {
   Conf.RemarksHotnessThreshold = RemarksHotnessThreshold;
   Conf.RemarksFormat = RemarksFormat;
 
-  Conf.MAttrs = {Args.getLastArgValue(OPT_feature, "").str()};
+  Conf.MAttrs = llvm::codegen::getMAttrs();
   std::optional<CodeGenOptLevel> CGOptLevelOrNone =
       CodeGenOpt::parseLevel(Args.getLastArgValue(OPT_O, "2")[0]);
   assert(CGOptLevelOrNone && "Invalid optimization level");

clang/tools/clang-nvlink-wrapper/NVLinkOpts.td

@@ -47,9 +47,6 @@ def arch : Separate<["--", "-"], "arch">,
 def : Joined<["--", "-"], "plugin-opt=mcpu=">,
   Flags<[HelpHidden, WrapperOnlyOption]>, Alias<arch>;
 
-def feature : Separate<["--", "-"], "feature">, Flags<[WrapperOnlyOption]>,
-  HelpText<"Specify the '+ptx' freature to use for LTO.">;
-
 def g : Flag<["-"], "g">, HelpText<"Specify that this was a debug compile.">;
 def debug : Flag<["--"], "debug">, Alias<g>;