[Driver] Add option to force undefined symbols during linking in BareMetal toolchain object.

[quic-garvgupt]

Add support for -u option to force defined symbols. This option is supported
by both lld and gnuld.

This is done as a part of the effort to merge RISCVToolchain object into
BareMetal toolchain object.

This is the 4th patch in the series of patches for merging RISCVToolchain object
into BareMetal toolchain object.

RFC:
https://discourse.llvm.org/t/merging-riscvtoolchain-and-baremetal-toolchains/75524

[quic-garvgupt]

• [RISCV] Integrate RISCV target in baremetal toolchain object and deprecate RISCVToolchain object #121831
• [RISCV][Driver] Add support for -m flag to linker job of Baremetal toolchain #134442
• [Driver] Forward sysroot from Driver to linker in BareMetal ToolChain Object #132808
• [Driver] Add option to force undefined symbols during linking in BareMetal toolchain object. #132807 👈 (View in Graphite)
• [Driver] Fix link order of BareMetal toolchain object #132806
• [Driver] Add support for crtbegin.o, crtend.o and libgloss lib to BareMetal toolchain object #121830
• [Driver] Add support for GCC installation detection in Baremetal toolchain #121829
• main

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[llvmbot]

@llvm/pr-subscribers-clang-driver
@llvm/pr-subscribers-backend-risc-v

@llvm/pr-subscribers-clang

Author: Garvit Gupta (quic-garvgupt)

Changes

Add support for -u option to force defined symbols. This option is supported
by both lld and gnuld.

This is done as a part of the effort to merge RISCVToolchain object into
BareMetal toolchain object.

This is the 4th patch in the series of patches for merging RISCVToolchain object
into BareMetal toolchain object.

RFC:
https://discourse.llvm.org/t/merging-riscvtoolchain-and-baremetal-toolchains/75524

---

Full diff: https://github.com/llvm/llvm-project/pull/132807.diff

3 Files Affected:

• (modified) clang/lib/Driver/ToolChains/BareMetal.cpp (+3-2)
• (removed) clang/test/Driver/riscv-args.c (-6)
• (added) clang/test/Driver/undefined-symbols.c (+15)

diff --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
index 919fc6fe71178..edf9ecc728282 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.cpp
+++ b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -566,8 +566,9 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
-  Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group,
-                            options::OPT_s, options::OPT_t, options::OPT_r});
+  Args.addAllArgs(CmdArgs,
+                  {options::OPT_L, options::OPT_u, options::OPT_T_Group,
+                   options::OPT_s, options::OPT_t, options::OPT_r});
 
   TC.AddFilePathLibArgs(Args, CmdArgs);
 
diff --git a/clang/test/Driver/riscv-args.c b/clang/test/Driver/riscv-args.c
deleted file mode 100644
index cab08e5b0f811..0000000000000
--- a/clang/test/Driver/riscv-args.c
+++ /dev/null
@@ -1,6 +0,0 @@
-// Check the arguments are correctly passed
-
-// Make sure -T is the last with gcc-toolchain option
-// RUN: %clang -### --target=riscv32 --gcc-toolchain= -Xlinker --defsym=FOO=10 -T a.lds -u foo %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=CHECK-LD %s
-// CHECK-LD: {{.*}} "--defsym=FOO=10" {{.*}} "-u" "foo" {{.*}} "-T" "a.lds"
diff --git a/clang/test/Driver/undefined-symbols.c b/clang/test/Driver/undefined-symbols.c
new file mode 100644
index 0000000000000..0ce0db43bccad
--- /dev/null
+++ b/clang/test/Driver/undefined-symbols.c
@@ -0,0 +1,15 @@
+// Check the arguments are correctly passed
+
+// Make sure -T is the last with gcc-toolchain option
+// RUN: %clang -### --target=riscv32 --gcc-toolchain= -Xlinker --defsym=FOO=10 -T a.lds -u foo %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-LD %s
+// CHECK-LD: {{.*}} "--defsym=FOO=10" {{.*}} "-u" "foo" {{.*}} "-T" "a.lds"
+
+// TODO: Merge this test with the above in the last patch when finally integrating riscv
+// Make sure -T is the last with gcc-toolchain option
+// RUN: %clang -### --target=aarch64-none-elf --gcc-toolchain= -Xlinker --defsym=FOO=10 -T a.lds -u foo %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-ARM-LD %s
+// RUN: %clang -### --target=armv6m-none-eabi --gcc-toolchain= -Xlinker --defsym=FOO=10 -T a.lds -u foo %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-ARM-LD %s
+// CHECK-ARM-LD: {{.*}} "-T" "a.lds" "-u" "foo" {{.*}} "--defsym=FOO=10"
+