[clang] 15f65af - [clang] Add option for -nolibc in Driver/ToolChains/Baremetal.cpp (#145700)

[via cfe-commits]

Author: William Huynh
Date: 2025-07-31T09:40:40+01:00
New Revision: 15f65afc7aa5c98ed3d3eeb14d7e5e4f2c4e02f4

URL: https://github.com/llvm/llvm-project/commit/15f65afc7aa5c98ed3d3eeb14d7e5e4f2c4e02f4
DIFF: https://github.com/llvm/llvm-project/commit/15f65afc7aa5c98ed3d3eeb14d7e5e4f2c4e02f4.diff

LOG: [clang] Add option for -nolibc in Driver/ToolChains/Baremetal.cpp (#145700)

Some tests in LLVM-libc require this flag
(https://github.com/llvm/llvm-project/issues/145349), which requires
compiler-rt to be linked in, but not the C library. With this change,
the `-nolibc` flag will not be ignored.

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/BareMetal.cpp
    clang/test/Driver/baremetal.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
index 207150ea6f322..25a16fe16eead 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.cpp
+++ b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -671,7 +671,8 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
     CmdArgs.push_back("--start-group");
     AddRunTimeLibs(TC, D, CmdArgs, Args);
-    CmdArgs.push_back("-lc");
+    if (!Args.hasArg(options::OPT_nolibc))
+      CmdArgs.push_back("-lc");
     if (TC.hasValidGCCInstallation() || detectGCCToolchainAdjacent(D))
       CmdArgs.push_back("-lgloss");
     CmdArgs.push_back("--end-group");

diff  --git a/clang/test/Driver/baremetal.cpp b/clang/test/Driver/baremetal.cpp
index 8b5ab4355087b..26f030d0618b7 100644
--- a/clang/test/Driver/baremetal.cpp
+++ b/clang/test/Driver/baremetal.cpp
@@ -163,6 +163,16 @@
 // RUN:   | FileCheck %s --check-prefix=CHECK-RTLIB-GCC
 // CHECK-RTLIB-GCC: -lgcc
 
+// RUN: %clang -### --target=arm-none-eabi -nolibc -rtlib=compiler-rt %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-NOLIBC
+// CHECK-NOLIBC-NOT: "-lc"
+// CHECK-NOLIBC: "{{[^"]*}}libclang_rt.builtins.a"
+
+// RUN: %clang -### --target=arm-none-eabi -nostdlib -rtlib=compiler-rt %s 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-NOSTDLIB
+// CHECK-NOSTDLIB-NOT: "-lc"
+// CHECK-NOSTDLIB-NOT: "{{[^"]*}}libclang_rt.builtins.a"
+
 // RUN: %clang -### --target=arm-none-eabi -v %s 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-SYSROOT-INC
 // CHECK-SYSROOT-INC-NOT: "-internal-isystem" "include"