[AMDGPU] Prepend --no-undefined option for linker instead of append

Previously, for linking in amdgpu contexts, the --no-undefined was appended to the options passed to lld,
overriding any user-supplied options via "-Wl," or "-Xlinker". We now prepend --no-undefined so that
the user options are respected.

Differential Revision: https://reviews.llvm.org/D158582

Author: lamb-j

clang/lib/Driver/ToolChains/AMDGPU.cpp

@@ -551,6 +551,9 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   std::string Linker = getToolChain().GetProgramPath(getShortName());
   ArgStringList CmdArgs;
+  CmdArgs.push_back("--no-undefined");
+  CmdArgs.push_back("-shared");
+
   addLinkerCompressDebugSectionsOption(getToolChain(), Args, CmdArgs);
   Args.AddAllArgs(CmdArgs, options::OPT_L);
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
@@ -560,8 +563,6 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   else if (Args.hasArg(options::OPT_mcpu_EQ))
     CmdArgs.push_back(Args.MakeArgString(
         "-plugin-opt=mcpu=" + Args.getLastArgValue(options::OPT_mcpu_EQ)));
-  CmdArgs.push_back("--no-undefined");
-  CmdArgs.push_back("-shared");
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
   C.addCommand(std::make_unique<Command>(

clang/test/Driver/amdgpu-toolchain-opencl.cl

@@ -28,3 +28,7 @@
 
 // RUN: %clang -### --target=amdgcn-amd-amdhsa-opencl -x cl -mcpu=fiji -nogpulib %s 2>&1 | FileCheck -check-prefix=CHK-LINK %s
 // CHK-LINK: ld.lld{{.*}} "--no-undefined" "-shared"
+
+// RUN: %clang -### --target=amdgcn-amd-amdhsa-opencl -Wl,--unresolved-symbols=ignore-all -x cl -mcpu=fiji -nogpulib %s 2>&1 | FileCheck -check-prefix=CHK-LINK_UR %s
+// RUN: %clang -### --target=amdgcn-amd-amdhsa-opencl -Xlinker --unresolved-symbols=ignore-all -x cl -mcpu=fiji -nogpulib %s 2>&1 | FileCheck -check-prefix=CHK-LINK_UR %s
+// CHK-LINK_UR: ld.lld{{.*}} "--no-undefined"{{.*}} "--unresolved-symbols=ignore-all"

clang/test/Driver/amdgpu-toolchain.c

@@ -10,6 +10,14 @@
 
 // DWARF_VER: "-dwarf-version=5"
 
+// RUN: %clang -### --target=amdgcn--amdhsa -x assembler \
+// RUN:  -Wl,--unresolved-symbols=ignore-all %s 2>&1 | FileCheck -check-prefix=AS_LINK_UR %s
+// RUN: %clang -### --target=amdgcn--amdhsa -x assembler \
+// RUN:  -Xlinker --unresolved-symbols=ignore-all %s 2>&1 | FileCheck -check-prefix=AS_LINK_UR %s
+
+// AS_LINK_UR: "-cc1as"
+// AS_LINK_UR: ld.lld{{.*}} "--no-undefined"{{.*}} "--unresolved-symbols=ignore-all"
+
 // RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx906 -nogpulib \
 // RUN:   -L. -flto -fconvergent-functions %s 2>&1 | FileCheck -check-prefixes=LTO,MCPU %s
 // RUN: %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx906 -nogpulib \