[clang] [LinkerWrapper] Forward `-mllvm` and `--offload-opt` arguments to device (PR #100424)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 updated https://github.com/llvm/llvm-project/pull/100424

>From 88b8b4fc649dd9c900fc941f1e03cd5fc097acc1 Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Wed, 24 Jul 2024 11:44:22 -0500
Subject: [PATCH] [LinkerWrapper] Forward `-mllvm` and `--offload-opt`
 arguments to device

Summary:
Previously we could parse these internally as they would be used by the
embedded LTO job. Now, this LTO is passed to the linker utilities which
means these need to be forwarded. So this can now either be done with
`--offload-opt` which works in the clang job, or with `-Xoffload-linker`
manually.

Fixes https://github.com/llvm/llvm-project/issues/100212
---
 clang/test/Driver/linker-wrapper.c                   | 10 ++++++++++
 .../clang-linker-wrapper/ClangLinkerWrapper.cpp      | 12 ++++++++++--
 .../tools/clang-linker-wrapper/LinkerWrapperOpts.td  |  2 +-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/clang/test/Driver/linker-wrapper.c b/clang/test/Driver/linker-wrapper.c
index 342907c1a3390..f165a410c1929 100644
--- a/clang/test/Driver/linker-wrapper.c
+++ b/clang/test/Driver/linker-wrapper.c
@@ -234,3 +234,13 @@ __attribute__((visibility("protected"), used)) int x;
 // RUN: | FileCheck %s --check-prefix=OVERRIDE
 // OVERRIDE-NOT: clang
 // OVERRIDE: /usr/bin/ld
+
+// RUN: clang-offload-packager -o %t.out \
+// RUN:   --image=file=%t.elf.o,kind=openmp,triple=amdgcn-amd-amdhsa,arch=gfx908
+// RUN: %clang -cc1 %s -triple x86_64-unknown-linux-gnu -emit-obj -o %t.o -fembed-offload-object=%t.out
+// RUN: clang-linker-wrapper --host-triple=x86_64-unknown-linux-gnu --dry-run --offload-opt=-pass-remarks=foo \
+// RUN:   --linker-path=/usr/bin/ld %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=OFFLOAD-OPT
+// RUN: clang-linker-wrapper --host-triple=x86_64-unknown-linux-gnu --dry-run -mllvm -pass-remarks=foo \
+// RUN:   --linker-path=/usr/bin/ld %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=OFFLOAD-OPT
+
+// OFFLOAD-OPT: clang{{.*}}-Wl,--plugin-opt=-pass-remarks=foo
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 4bb021eae25a8..2db7b6ac823ec 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -297,7 +297,8 @@ Expected<std::string> findProgram(StringRef Name, ArrayRef<StringRef> Paths) {
 /// supported by the toolchain.
 bool linkerSupportsLTO(const ArgList &Args) {
   llvm::Triple Triple(Args.getLastArgValue(OPT_triple_EQ));
-  return Triple.isNVPTX() || Triple.isAMDGPU();
+  return Triple.isNVPTX() || Triple.isAMDGPU() ||
+         Args.getLastArgValue(OPT_linker_path_EQ).ends_with("ld.lld");
 }
 
 /// Returns the hashed value for a constant string.
@@ -524,6 +525,13 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args) {
       Args.MakeArgString("-" + OptLevel),
   };
 
+  // Forward all of the `--offload-opt` and similar options to the device.
+  if (linkerSupportsLTO(Args)) {
+    for (auto &Arg : Args.filtered(OPT_offload_opt_eq_minus, OPT_mllvm))
+      CmdArgs.push_back(
+          Args.MakeArgString("-Wl,--plugin-opt=" + StringRef(Arg->getValue())));
+  }
+
   if (!Triple.isNVPTX())
     CmdArgs.push_back("-Wl,--no-undefined");
 
@@ -1756,7 +1764,7 @@ int main(int Argc, char **Argv) {
   for (const opt::Arg *Arg : Args.filtered(OPT_mllvm))
     NewArgv.push_back(Arg->getValue());
   for (const opt::Arg *Arg : Args.filtered(OPT_offload_opt_eq_minus))
-    NewArgv.push_back(Args.MakeArgString(StringRef("-") + Arg->getValue()));
+    NewArgv.push_back(Arg->getValue());
   SmallVector<PassPlugin, 1> PluginList;
   PassPlugins.setCallback([&](const std::string &PluginPath) {
     auto Plugin = PassPlugin::Load(PluginPath);
diff --git a/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td b/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
index 9c27e588fc4f5..a87d5ec8aa9b3 100644
--- a/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
+++ b/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
@@ -98,7 +98,7 @@ def mllvm : Separate<["-"], "mllvm">, Flags<[WrapperOnlyOption]>,
   HelpText<"Arguments passed to LLVM, including Clang invocations, for which "
            "the '-mllvm' prefix is preserved. Use '-mllvm --help' for a list "
            "of options.">;
-def offload_opt_eq_minus : Joined<["--", "-"], "offload-opt=-">, Flags<[HelpHidden, WrapperOnlyOption]>,
+def offload_opt_eq_minus : Joined<["--", "-"], "offload-opt=">, Flags<[HelpHidden, WrapperOnlyOption]>,
   HelpText<"Options passed to LLVM, not including the Clang invocation. Use "
            "'--offload-opt=--help' for a list of options.">;