[clang] Add necessary linker flags when -static-pie is enabled in BareMetal Toolchain (PR #147589)

[Garvit Gupta via cfe-commits]

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@@ -599,11 +599,18 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   const Driver &D = getToolChain().getDriver();
   const llvm::Triple::ArchType Arch = TC.getArch();
   const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
+  const bool IsStaticPIE = getStaticPIE(Args, TC);
 
   if (!D.SysRoot.empty())
     CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
 
   CmdArgs.push_back("-Bstatic");
+  if (IsStaticPIE) {
+    CmdArgs.push_back("-pie");
+    CmdArgs.push_back("--no-dynamic-linker");
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quic-garvgupt wrote:

This change is needed for both LLD and GNU LD. I dont see `static -pie` flags being passed by default for LLD if `-static-pie` is passed to clang driver. Moreover, without this change we get a unused argument warning as well.
Pls see below for verbose logs.

`clang --target=aarch64-none-elf -fuse-ld=lld -static-pie empty.c -###`

`clang: warning: argument unused during compilation: '-static-pie' [-Wunused-command-line-argument]`
`...............................`
`ld.lld" "-Bstatic" "-m" "aarch64linux" "-EL" "crt0.o" "-L/prj/llvm-arm/hexbuild_home/nightly/install/community-mainline/cross/2025-07-09/bin/../lib/clang-runtimes/aarch64-none-elf/lib" "-L/prj/llvm-arm/hexbuild_home/nightly/install/community-mainline/cross/2025-07-09/lib/clang/21/lib/aarch64-unknown-none-elf" "-L/prj/llvm-arm/hexbuild_home/nightly/install/community-mainline/cross/2025-07-09/bin/../lib/clang-runtimes/aarch64-none-elf/lib" "/tmp/empty-09660d.o" "--start-group" "/prj/llvm-arm/hexbuild_home/nightly/install/community-mainline/cross/2025-07-09/lib/clang/21/lib/aarch64-unknown-none-elf/libclang_rt.builtins.a" "-lc" "--end-group" "-o" "a.out"`

Pls let me know if I missed something in your comment or interpreted it differently.

https://github.com/llvm/llvm-project/pull/147589