[clang] [LinkerWrapper] Accenp some neede COFF linker argument (PR #72889)

Joseph Huber via cfe-commits cfe-commits at lists.llvm.org
Mon Nov 20 08:23:18 PST 2023


https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/72889

Summary:
The linker wrapper is a utility used to create offloading programs from
single-source offloading languages such as OpenMP or CUDA. This is done
by embedding device code into the host object, then feeding it into the
linker wrapper which extracts the accelerator object files, links them,
then wraps them in registration code for the target  runtime. This
previously has only worked in Linux / ELF platforms.

This patch attempts to hand Windows / COFF inputs by also accepting COFF
forms of certain linker arguments we use internally. The important
arguments are library search paths, so we can identify libraries which
may contain device code, libraries themselves, and the output name used
for intermediate output.

I am not intimately familiar with the semantics here for the semantics
in how a `lib` file is earched. I am simply treating `foo.lib` as the
GNU equivalent `-l:foo.lib` in the search logic. Similarly, I am
assuming that static libraries will be llvm-ar style libraries. I will
need to investigate the actual deficiencies later, but this should be a
good starting point along with https://github.com/llvm/llvm-project/pull/72697


>From d06171561581d9d15c14f756c8999b478e1d769e Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Mon, 20 Nov 2023 10:12:04 -0600
Subject: [PATCH] [LinkerWrapper] Accenp some neede COFF linker argument

Summary:
The linker wrapper is a utility used to create offloading programs from
single-source offloading languages such as OpenMP or CUDA. This is done
by embedding device code into the host object, then feeding it into the
linker wrapper which extracts the accelerator object files, links them,
then wraps them in registration code for the target  runtime. This
previously has only worked in Linux / ELF platforms.

This patch attempts to hand Windows / COFF inputs by also accepting COFF
forms of certain linker arguments we use internally. The important
arguments are library search paths, so we can identify libraries which
may contain device code, libraries themselves, and the output name used
for intermediate output.

I am not intimately familiar with the semantics here for the semantics
in how a `lib` file is earched. I am simply treating `foo.lib` as the
GNU equivalent `-l:foo.lib` in the search logic. Similarly, I am
assuming that static libraries will be llvm-ar style libraries. I will
need to investigate the actual deficiencies later, but this should be a
good starting point along with https://github.com/llvm/llvm-project/pull/72697
---
 clang/test/Driver/linker-wrapper.c             |  8 ++++++++
 .../ClangLinkerWrapper.cpp                     | 18 +++++++++++++-----
 .../clang-linker-wrapper/LinkerWrapperOpts.td  |  5 +++++
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/clang/test/Driver/linker-wrapper.c b/clang/test/Driver/linker-wrapper.c
index da7bdc22153ceae..e82febd61823102 100644
--- a/clang/test/Driver/linker-wrapper.c
+++ b/clang/test/Driver/linker-wrapper.c
@@ -140,3 +140,11 @@
 // RUN:   --linker-path=/usr/bin/ld -- %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=CLANG-BACKEND
 
 // CLANG-BACKEND: clang{{.*}} -o {{.*}}.img --target=amdgcn-amd-amdhsa -mcpu=gfx908 -O2 -Wl,--no-undefined {{.*}}.bc
+
+// RUN: clang-offload-packager -o %t.out \
+// RUN:   --image=file=%t.elf.o,kind=openmp,triple=nvptx64-nvidia-cuda,arch=sm_70
+// RUN: %clang -cc1 %s -triple x86_64-unknown-windows-msvc -emit-obj -o %t.o -fembed-offload-object=%t.out
+// RUN: clang-linker-wrapper --host-triple=x86_64-unknown-windows-msvc --dry-run \
+// RUN:   --linker-path=/usr/bin/lld-link -- %t.o -libpath:./ -out:a.exe 2>&1 | FileCheck %s --check-prefix=COFF
+
+// COFF: "/usr/bin/lld-link" {{.*}}.o -libpath:./ -out:a.exe {{.*}}openmp.image.wrapper{{.*}}
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index bafe8ace60d1cea..db0ce3e2a190192 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -254,7 +254,7 @@ Error runLinker(ArrayRef<StringRef> Files, const ArgList &Args) {
       continue;
 
     Arg->render(Args, NewLinkerArgs);
-    if (Arg->getOption().matches(OPT_o))
+    if (Arg->getOption().matches(OPT_o) || Arg->getOption().matches(OPT_out))
       llvm::transform(Files, std::back_inserter(NewLinkerArgs),
                       [&](StringRef Arg) { return Args.MakeArgString(Arg); });
   }
@@ -1188,7 +1188,7 @@ searchLibraryBaseName(StringRef Name, StringRef Root,
 /// `-lfoo` or `-l:libfoo.a`.
 std::optional<std::string> searchLibrary(StringRef Input, StringRef Root,
                                          ArrayRef<StringRef> SearchPaths) {
-  if (Input.startswith(":"))
+  if (Input.startswith(":") || Input.ends_with(".lib"))
     return findFromSearchPaths(Input.drop_front(), Root, SearchPaths);
   return searchLibraryBaseName(Input, Root, SearchPaths);
 }
@@ -1339,7 +1339,7 @@ Expected<SmallVector<OffloadFile>> getDeviceInput(const ArgList &Args) {
 
   StringRef Root = Args.getLastArgValue(OPT_sysroot_EQ);
   SmallVector<StringRef> LibraryPaths;
-  for (const opt::Arg *Arg : Args.filtered(OPT_library_path))
+  for (const opt::Arg *Arg : Args.filtered(OPT_library_path, OPT_libpath))
     LibraryPaths.push_back(Arg->getValue());
 
   BumpPtrAllocator Alloc;
@@ -1348,7 +1348,7 @@ Expected<SmallVector<OffloadFile>> getDeviceInput(const ArgList &Args) {
   // Try to extract device code from the linker input files.
   SmallVector<OffloadFile> InputFiles;
   DenseMap<OffloadFile::TargetID, DenseMap<StringRef, Symbol>> Syms;
-  bool WholeArchive = false;
+  bool WholeArchive = Args.hasArg(OPT_wholearchive_flag) ? true : false;
   for (const opt::Arg *Arg : Args.filtered(
            OPT_INPUT, OPT_library, OPT_whole_archive, OPT_no_whole_archive)) {
     if (Arg->getOption().matches(OPT_whole_archive) ||
@@ -1474,9 +1474,17 @@ int main(int Argc, char **Argv) {
   Verbose = Args.hasArg(OPT_verbose);
   DryRun = Args.hasArg(OPT_dry_run);
   SaveTemps = Args.hasArg(OPT_save_temps);
-  ExecutableName = Args.getLastArgValue(OPT_o, "a.out");
   CudaBinaryPath = Args.getLastArgValue(OPT_cuda_path_EQ).str();
 
+  llvm::Triple Triple(
+      Args.getLastArgValue(OPT_host_triple_EQ, sys::getDefaultTargetTriple()));
+  if (Args.hasArg(OPT_o))
+    ExecutableName = Args.getLastArgValue(OPT_o, "a.out");
+  else if (Args.hasArg(OPT_out))
+    ExecutableName = Args.getLastArgValue(OPT_out, "a.exe");
+  else
+    ExecutableName = Triple.isOSWindows() ? "a.exe" : "a.out";
+
   parallel::strategy = hardware_concurrency(1);
   if (auto *Arg = Args.getLastArg(OPT_wrapper_jobs)) {
     unsigned Threads = 0;
diff --git a/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td b/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
index 2ce6ee0d21d1d6e..21e479dd31c9721 100644
--- a/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
+++ b/clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
@@ -126,3 +126,8 @@ def version : Flag<["--", "-"], "version">, Flags<[HelpHidden]>, Alias<v>;
 
 def whole_archive : Flag<["--", "-"], "whole-archive">, Flags<[HelpHidden]>;
 def no_whole_archive : Flag<["--", "-"], "no-whole-archive">, Flags<[HelpHidden]>;
+
+// COFF-style linker options.
+def out : Joined<["/", "-", "/?", "-?"], "out:">, Flags<[HelpHidden]>;
+def libpath : Joined<["/", "-", "/?", "-?"], "libpath:">, Flags<[HelpHidden]>;
+def wholearchive_flag : Joined<["/", "-", "/?", "-?"], "wholearchive">, Flags<[HelpHidden]>;



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