[HIPSPV][4/4] Add option to use llc to emit SPIR-V

[linjamaki]

Summary

Add two hidden options for emitting SPIR-V binary via LLC. The options are only meant for testing and development.

´--spirv-use-llc´ invokes in-tree llc. Not usable at the moment until the SPIR-V backend lands on LLVM.

´--spirv-use-llc=<path-to-llc>´ invokes llc tool given as path. Meant for trying out out-of-tree SPIR-V backend.

The HIPSPV tool chain is the only one responding to these options.

[linjamaki]

Rebase.

[linjamaki]

Remove metavar from --spirv-use-llc.

[Anastasia]

Ok, is the idea to deprecate this flag once we switch to llc by default then?

[linjamaki]

In D110685#3044993, @Anastasia wrote:

Ok, is the idea to deprecate this flag once we switch to llc by default then?

The idea is to remove the flags if no one else needs them when the HIPSPV tool chain switches over to llc.

[linjamaki]

Rebase.

[linjamaki]

Rebase.

[Anastasia]

I think it might make more sense to use the option -fno-llvm-spirv as we don't advertise llc as a tool to the developers but llvm-spirv we do.

[linjamaki]

Sounds good to me. I’ll make a new patch when there is a need for it and close this one.

[Anastasia]

Actually after some more thinking I have decided to go for a generic flag and I have created the review for it: https://reviews.llvm.org/D125679. Perhaps you can built your functionality on top of it when you get to it.

clang/include/clang/Driver/Options.td

def fmemory_profile_EQ : Joined<["-"], "fmemory-profile=">,
     HelpText<"Enable heap memory profiling and dump results into <directory>">;
 
 def spirv_max_version_EQ : Joined<["--"], "spirv-max-version">,
     HelpText<"Specify maximum SPIR-V version which can be emitted">;
 def spirv_ext_EQ : CommaJoined<["--"], "spirv-ext">,
     HelpText<"Specify comma separated list of allowed/disallowed SPIR-V "
     "extensions prefixed with '+' or '-'. '+' and '-' allows and disallows "
     "the extension, respectively. Special value 'all' affects all extensions">;
+def spirv_use_llc : Flag<["--"], "spirv-use-llc">, Flags<[HelpHidden]>,
+    HelpText<"Use (in-tree) llc to emit SPIR-V. Use for development and "
+    "testing only.">;
+def spirv_use_llc_EQ : Joined<["--"], "spirv-use-llc=">,
+    MetaVarName<"<path>">, Flags<[HelpHidden]>,
+    HelpText<"Use speficied llc to emit SPIR-V. Use for development and "
+    "testing only.">;
 
 // Begin sanitizer flags. These should all be core options exposed in all driver
 // modes.
 let Flags = [CC1Option, CoreOption] in {
 
 def fsanitize_EQ : CommaJoined<["-"], "fsanitize=">, Group<f_clang_Group>,
                    MetaVarName<"<check>">,
                    HelpText<"Turn on runtime checks for various forms of undefined "

clang/lib/Driver/ToolChains/HIPSPV.cpp

if (!PassPluginPath.empty()) {
     const char *Opt = Args.MakeArgString(getToolChain().GetProgramPath("opt"));
     C.addCommand(std::make_unique<Command>(
         JA, *this, ResponseFileSupport::None(), Opt, OptArgs, Inputs, Output));
     TempFile = OptOutput;
   }
 
   // Emit SPIR-V binary.
 
+  // Use llc. Meant for testing out LLVM SPIR-V backend. Eventually HIPSPV will
+  // switch to use in-tree SPIR-V backend for binary emission.
+  if (auto *A = Args.getLastArg(options::OPT_spirv_use_llc,
+                                options::OPT_spirv_use_llc_EQ)) {
+    assert(A->getNumValues() <= 1);
+    const char *LlcExe = nullptr;
+    if (A->getNumValues() == 1 && !StringRef(A->getValue()).empty())
+      LlcExe = A->getValue();
+    else
+      LlcExe = Args.MakeArgString(getToolChain().GetProgramPath("llc"));
+    ArgStringList LlcArgs{"--mattr=+spirv1.1", "--filetype=obj", TempFile, "-o",
+                          Output.getFilename()};
+    C.addCommand(std::make_unique<Command>(JA, *this,
+                                           ResponseFileSupport::None(), LlcExe,
+                                           LlcArgs, Inputs, Output));
+    return;
+  }
+
+  // Use SPIRV-LLVM Translator.
   llvm::opt::ArgStringList TrArgs;
   SPIRV::addTranslatorArgs(Args, TrArgs);
   if (!Args.hasArg(options::OPT_spirv_max_version_EQ))
     TrArgs.push_back("--spirv-max-version=1.1");
   if (!Args.hasArg(options::OPT_spirv_ext_EQ))
     TrArgs.push_back("--spirv-ext=+all");
 
   InputInfo TrInput = InputInfo(types::TY_LLVM_BC, TempFile, "");

clang/test/Driver/hipspv-options.hip

+// REQUIRES: clang-driver
+// REQUIRES: x86-registered-target
+// UNSUPPORTED: system-windows
+
+// RUN: %clang -### -target x86_64-linux-gnu --offload=spirv64 \
+// RUN:   --hip-path=%S/Inputs/hipspv -nogpuinc -nogpulib %s \
+// RUN:   --spirv-use-llc=/foo/bar/llc 2>&1 | FileCheck %s
+
+// CHECK-NOT: llvm-spirv
+// CHECK: "/foo/bar/llc" "--mattr=+spirv1.1" "--filetype=obj" "{{.*}}.bc"
+// CHECK-SAME: "-o" "{{.*}}.out"
+