[clang] [HIP] Fix `-flto` overriding `--no-lto` not that it is default (PR #202699)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/202699

Summary:
The previous changes to LTO made the flto flag passed by default which
overrode the hack we did to ervert to the old non-LTO pipline. This is a
temporary hack so I'm hacking it even further to fix it.


>From 53dde9652e2e416feb997f445c7480327cc0f55f Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Tue, 9 Jun 2026 10:53:33 -0500
Subject: [PATCH] [HIP] Fix `-flto` overriding `--no-lto` not that it is
 default

Summary:
The previous changes to LTO made the flto flag passed by default which
overrode the hack we did to ervert to the old non-LTO pipline. This is a
temporary hack so I'm hacking it even further to fix it.
---
 .../clang-linker-wrapper/ClangLinkerWrapper.cpp | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 6e4fc7060389c..cfdd11e1d298d 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -534,16 +534,6 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
     Triple.isAMDGPU() ? CmdArgs.push_back(Args.MakeArgString("-mcpu=" + Arch))
                       : CmdArgs.push_back(Args.MakeArgString("-march=" + Arch));
 
-  // AMDGPU defaults to the LTO pipeline. Non-RDC HIP uses the conventional
-  // non-LTO pipeline so device codegen still runs here, in parallel, instead
-  // of being deferred to the LTO link.
-  // FIXME: This is a stop-gap for non-RDC. Longer term, RDC and non-RDC should
-  // share a unified interface so runtime libraries can be provided to non-RDC
-  // compilations without relying on -mlink-builtin-bitcode.
-  bool NonLTOAMDGPU = Triple.isAMDGPU() && Args.hasArg(OPT_no_lto);
-  if (Triple.isAMDGPU() && !NonLTOAMDGPU)
-    CmdArgs.push_back("-flto");
-
   // Forward all of the `--offload-opt` and `-mllvm` options to the device.
   for (auto &Arg : Args.filtered(OPT_offload_opt_eq_minus, OPT_mllvm))
     CmdArgs.append(
@@ -557,7 +547,9 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
   // Force the IR input language so Clang runs the compile and backend phases
   // instead of treating them as linker inputs, which would defer codegen to
   // the LTO link and defeat the non-LTO pipeline.
-  if (NonLTOAMDGPU)
+  // FIXME: This is a stop-gap for non-RDC. Longer term, RDC and non-RDC should
+  //        share a unified interface.
+  if (Args.hasArg(OPT_no_lto))
     CmdArgs.append({"-x", "ir"});
   for (StringRef InputFile : InputFiles)
     CmdArgs.push_back(InputFile);
@@ -621,6 +613,9 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
   for (StringRef Arg : Args.getAllArgValues(OPT_compiler_arg_EQ))
     CmdArgs.push_back(Args.MakeArgString(Arg));
 
+  if (Args.hasArg(OPT_no_lto))
+    CmdArgs.append({"-flto=none", "-Wno-unused-command-line-argument"});
+
   if (Error Err = executeCommands(*ClangPath, CmdArgs))
     return std::move(Err);