[PATCH] D70416: [Driver] Make -static-libgcc imply static libunwind

[Josh Kunz via Phabricator via cfe-commits]

jkz created this revision.
jkz added reviewers: saugustine, sivachandra.
Herald added a project: clang.

In the GNU toolchain, `-static-libgcc` implies that the unwindlib will be linked statically. However, when `--unwindlib=libunwind`, this flag is ignored, and a bare `-lunwind` is added to the linker args.  Unfortunately, this means that if both `libunwind.so`, and `libunwind.a` are present in the library path, `libunwind.so` will be chosen in all cases where `-static` is not set.

This change makes `-static-libgcc` affect the `-l` flag produced by `--unwindlib=libunwind`. After this patch, providing `-static-libgcc --unwindlib=libunwind` will cause the driver to explicitly emit `-l:libunwind.a` to statically link libunwind. For all other cases it will emit `-l:libunwind.so` matching current behavior with a more explicit link line.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70416

Files:
  clang/lib/Driver/ToolChains/CommonArgs.cpp
  clang/test/Driver/compiler-rt-unwind.c


Index: clang/test/Driver/compiler-rt-unwind.c
===================================================================
--- clang/test/Driver/compiler-rt-unwind.c
+++ clang/test/Driver/compiler-rt-unwind.c
@@ -13,7 +13,15 @@
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=RTLIB-GCC-UNWINDLIB-COMPILER-RT %s
 // RTLIB-GCC-UNWINDLIB-COMPILER-RT: "{{.*}}lgcc"
-// RTLIB-GCC-UNWINDLIB-COMPILER-RT: "{{.*}}lunwind"
+// RTLIB-GCC-UNWINDLIB-COMPILER-RT: "{{.*}}l:libunwind.so"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux -rtlib=libgcc --unwindlib=libunwind \
+// RUN:     -static-libgcc \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-GCC-STATIC-UNWINDLIB-COMPILER-RT %s
+// RTLIB-GCC-STATIC-UNWINDLIB-COMPILER-RT: "{{.*}}lgcc"
+// RTLIB-GCC-STATIC-UNWINDLIB-COMPILER-RT: "{{.*}}l:libunwind.a"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1   \
 // RUN:     --target=x86_64-unknown-linux -rtlib=compiler-rt \
Index: clang/lib/Driver/ToolChains/CommonArgs.cpp
===================================================================
--- clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1209,7 +1209,10 @@
     break;
   }
   case ToolChain::UNW_CompilerRT:
-    CmdArgs.push_back("-lunwind");
+    if (LGT == LibGccType::StaticLibGcc)
+      CmdArgs.push_back("-l:libunwind.a");
+    else
+      CmdArgs.push_back("-l:libunwind.so");
     break;
   }
 


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