[PATCH] D129424: [LinkerWrapper] Forward `-mllvm` options to the linker wrapper

[Joseph Huber via Phabricator via cfe-commits]

jhuber6 created this revision.
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This patch adds the ability to use `-mllvm` options in the linker
wrapper when performing bitcode linking or the module compilation.
This is done by passing in the LLVM argument to the clang-linker-wrapper
tool. Inside the linker-wrapper tool we invoke the `CommandLine` parser
solely for forwarding command line options to the `clang-linker-wrapper`
to the LLVM tools that also use the `CommandLine` parser. The actual
arguments to the linker wrapper are parsed using the `Opt` library
instead.

For example, in the following command the `CommandLine` parser will attempt to
parse `abc`, while the `opt` parser takes `-mllvm <arg>` and ignores it so it is
not passed to the linker arguments.

  clang-linker-wrapper -mllvm -abc -- <linker-args>

As far as I can tell this is the easiest way to forward arguments to
LLVM tool invocations. If there is a better way to pass these arguments
(such as through the LTO config) let me know.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D129424

Files:
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/test/Driver/linker-wrapper.c
  clang/test/Driver/openmp-offload.c
  clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td


Index: clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
===================================================================
--- clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
+++ clang/tools/clang-linker-wrapper/LinkerWrapperOpts.td
@@ -70,6 +70,10 @@
 def separator : Flag<["--"], "">, Flags<[WrapperOnlyOption]>,
   HelpText<"The separator for the wrapped linker arguments">;
 
+// Arguments for the LLVM backend.
+def mllvm : Separate<["--", "-"], "mllvm">, Flags<[WrapperOnlyOption]>,
+  MetaVarName<"<arg>">, HelpText<"Arguments passed to the LLVM invocation">;
+
 // Standard linker flags also used by the linker wrapper.
 def sysroot_EQ : Joined<["--"], "sysroot">, HelpText<"Set the system root">;
 
Index: clang/test/Driver/openmp-offload.c
===================================================================
--- clang/test/Driver/openmp-offload.c
+++ clang/test/Driver/openmp-offload.c
@@ -664,7 +664,13 @@
 // CHK-NEW-DRIVER: clang-linker-wrapper{{.*}}"--host-triple=powerpc64le-unknown-linux"{{.*}}--{{.*}}"-lomp"{{.*}}"-lomptarget"
 
 /// Check arguments to the linker wrapper
-// RUN:   %clang -### --target=powerpc64le-linux -fopenmp=libomp -fopenmp-targets=powerpc64le-ibm-linux-gnu -g -fopenmp-new-driver %s 2>&1 \
+// RUN:   %clang -### --target=powerpc64le-linux -fopenmp=libomp -fopenmp-targets=powerpc64le-ibm-linux-gnu -g %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHK-NEW-DRIVER-DEBUG %s
 
 // CHK-NEW-DRIVER-DEBUG: clang-linker-wrapper{{.*}}"--device-debug
+
+/// Check arguments to the linker wrapper
+// RUN:   %clang -### --target=powerpc64le-linux -fopenmp=libomp -fopenmp-targets=powerpc64le-ibm-linux-gnu \
+// RUN:     -mllvm -abc %s 2>&1 | FileCheck -check-prefix=CHK-NEW-DRIVER-MLLVM %s
+
+// CHK-NEW-DRIVER-MLLVM: clang-linker-wrapper{{.*}}"-abc
Index: clang/test/Driver/linker-wrapper.c
===================================================================
--- clang/test/Driver/linker-wrapper.c
+++ clang/test/Driver/linker-wrapper.c
@@ -39,10 +39,11 @@
 // CPU_LINK: ld.lld{{.*}}-m elf_x86_64 -shared -Bsymbolic -o {{.*}}.out {{.*}}.o {{.*}}.o
 
 // RUN: %clang -cc1 %s -triple x86_64-unknown-linux-gnu -emit-obj -o %t.o
-// RUN: clang-linker-wrapper --dry-run --host-triple=x86_64-unknown-linux-gnu \
+// RUN: clang-linker-wrapper --dry-run --host-triple=x86_64-unknown-linux-gnu -mllvm -abc \
 // RUN:   --linker-path=/usr/bin/ld.lld -- -a -b -c %t.o -o a.out 2>&1 | FileCheck %s --check-prefix=HOST_LINK
 
 // HOST_LINK: ld.lld{{.*}}-a -b -c {{.*}}.o -o a.out
+// HOST_LINK-NOT: ld.lld{{.*}}-abc
 
 // RUN: clang-offload-packager -o %t.out \
 // RUN:   --image=file=%S/Inputs/dummy-bc.bc,kind=openmp,triple=nvptx64-nvidia-cuda,arch=sm_70 \
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -8462,6 +8462,12 @@
   }
   Args.ClaimAllArgs(options::OPT_Xoffload_linker);
 
+  // Forward `-mllvm` arguments to the LLVM invocations if present.
+  for (auto *Arg : Args.filtered(options::OPT_mllvm)) {
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back(Arg->getValue());
+  }
+
   // Add the linker arguments to be forwarded by the wrapper.
   CmdArgs.push_back(Args.MakeArgString(Twine("--linker-path=") +
                                        LinkCommand->getExecutable()));


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