[clang] Allow using BareMetal toolchain with LLVM_ENABLE_PER_TARGET_RUNTIME_DIR compiler-rt

If you build compiler-rt with LLVM_ENABLE_PER_TARGET_RUNTIME_DIR then
the library filename will be "libclang_rt.builtins.a" instead of
"libclang_rt.builtins-<ARCH>.a"

The ToolChain::getCompilerRT method uses the "libclang_rt.builtins.a"
name if it can find the file in the library directories. If it can't
then it falls back to using "libclang_rt.builtins-<ARCH>.a". This
change adds the library directory such that "libclang_rt.builtins.a"
can be found.

Differential Revision: https://reviews.llvm.org/D139822

Author: mplatings

clang/lib/Driver/ToolChains/BareMetal.cpp

@@ -103,6 +103,7 @@ BareMetal::BareMetal(const Driver &D, const llvm::Triple &Triple,
   if (!SysRoot.empty()) {
     llvm::sys::path::append(SysRoot, "lib");
     getFilePaths().push_back(std::string(SysRoot));
+    getLibraryPaths().push_back(std::string(SysRoot));
   }
 }
 

clang/test/Driver/baremetal.cpp

@@ -340,3 +340,27 @@
 // CHECK-RV32IMAFC-NEXT: ld{{(.exe)?}}" "{{.*}}.o" "-Bstatic"
 // CHECK-RV32IMAFC-SAME: "-L[[SYSROOT:[^"]+]]{{[/\\]+}}rv32imafc{{[/\\]+}}ilp32f{{[/\\]+}}lib"
 // CHECK-RV32IMAFC-SAME: "-L[[RESOURCE_DIR:[^"]+]]{{[/\\]+}}lib{{[/\\]+}}baremetal{{[/\\]+}}rv32imafc{{[/\\]+}}ilp32f"
+
+// Check that compiler-rt library without the arch filename suffix will
+// be used if present.
+// RUN: rm -rf %T/baremetal_clang_rt_noarch
+// RUN: mkdir -p %T/baremetal_clang_rt_noarch/lib
+// RUN: touch %T/baremetal_clang_rt_noarch/lib/libclang_rt.builtins.a
+// RUN: %clang %s -### 2>&1 \
+// RUN:     --target=armv6m-none-eabi \
+// RUN:     --sysroot=%T/baremetal_clang_rt_noarch \
+// RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-NOARCH %s
+// CHECK-CLANGRT-NOARCH: "-lclang_rt.builtins"
+// CHECK-CLANGRT-NOARCH-NOT: "-lclang_rt.builtins-armv6m"
+
+// Check that compiler-rt library with the arch filename suffix will be
+// used if present.
+// RUN: rm -rf %T/baremetal_clang_rt_arch
+// RUN: mkdir -p %T/baremetal_clang_rt_arch/lib
+// RUN: touch %T/baremetal_clang_rt_arch/lib/libclang_rt.builtins-armv6m.a
+// RUN: %clang %s -### 2>&1 \
+// RUN:     --target=armv6m-none-eabi \
+// RUN:     --sysroot=%T/baremetal_clang_rt_arch \
+// RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-ARCH %s
+// CHECK-CLANGRT-ARCH: "-lclang_rt.builtins-armv6m"
+// CHECK-CLANGRT-ARCH-NOT: "-lclang_rt.builtins"