Remove use of `--exclude-libs` for libgcc/libcompiler_rt.
This dates from before we had linker scripts, and isn't needed any more.
Also remove a similar obsolete libgcc workaround for unwinding.
Also clarify some of the commentary.
Test: nm before and after.
Change-Id: Icbc78559374bd3792ed4a1a11ebe54b27d0cce7a
diff --git a/linker/Android.bp b/linker/Android.bp
index ce5eff9..143dbd5 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -1,14 +1,3 @@
-// ========================================================
-// linker_wrapper - Linux Bionic (on the host)
-// ========================================================
-
-// This is used for bionic on (host) Linux to bootstrap our linker embedded into
-// a binary.
-//
-// Host bionic binaries do not have a PT_INTERP section, instead this gets
-// embedded as the entry point, and the linker is embedded as ELF sections in
-// each binary. There's a linker script that sets all of that up (generated by
-// extract_linker), and defines the extern symbols used in this file.
package {
default_team: "trendy_team_native_tools_libraries",
default_applicable_licenses: ["bionic_linker_license"],
@@ -25,6 +14,17 @@
],
}
+// ========================================================
+// linker_wrapper - Linux Bionic (on the host)
+// ========================================================
+
+// This is used for bionic on (host) Linux to bootstrap our linker embedded into
+// a binary.
+//
+// Host bionic binaries do not have a PT_INTERP section, instead this gets
+// embedded as the entry point, and the linker is embedded as ELF sections in
+// each binary. There's a linker script that sets all of that up (generated by
+// extract_linker), and defines the extern symbols used in this file.
cc_object {
name: "linker_wrapper",
host_supported: true,
@@ -327,8 +327,10 @@
},
},
+ static_executable: true,
+
// -shared is used to overwrite the -Bstatic and -static flags triggered by enabling
- // static_executable. This dynamic linker is actually a shared object linked with static
+ // static_executable. The dynamic linker is actually a shared object linked with static
// libraries.
ldflags: [
"-shared",
@@ -344,18 +346,14 @@
"-Wl,--pack-dyn-relocs=relr",
],
- // we are going to link libc++_static manually because
- // when stl is not set to "none" build system adds libdl
- // to the list of static libraries which needs to be
- // avoided in the case of building loader.
+ // We link libc++_static manually because otherwise the build system will
+ // automatically add libdl to the list of static libraries.
stl: "none",
- // we don't want crtbegin.o (because we have begin.o), so unset it
- // just for this module
+ // We don't want crtbegin.o (because we have our own arch/*/begin.o),
+ // so unset it just for this module.
nocrt: true,
- static_executable: true,
-
// Insert an extra objcopy step to add prefix to symbols. This is needed to prevent gdb
// looking up symbols in the linker by mistake.
prefix_symbols: "__dl_",
@@ -369,26 +367,17 @@
"liblinker_main",
"liblinker_malloc",
- // Use a version of libc++ built without exceptions, because accessing EH globals uses
- // ELF TLS, which is not supported in the loader.
+ // We use a version of libc++ built without exceptions,
+ // because accessing EH globals uses ELF TLS,
+ // which is not supported in the loader.
"libc++_static_noexcept",
+
"libc_nomalloc",
"libc_dynamic_dispatch",
"libm",
"libunwind",
],
- // Ensure that if the linker needs __gnu_Unwind_Find_exidx, then the linker will have a
- // definition of the symbol. The linker links against libgcc.a, whose arm32 unwinder has a weak
- // reference to __gnu_Unwind_Find_exidx, which isn't sufficient to pull in the strong definition
- // of __gnu_Unwind_Find_exidx from libc. An unresolved weak reference would create a
- // non-relative dynamic relocation in the linker binary, which complicates linker startup.
- //
- // This line should be unnecessary because the linker's dependency on libunwind_llvm.a should
- // override libgcc.a, but this line provides a simpler guarantee. It can be removed once the
- // linker stops linking against libgcc.a's arm32 unwinder.
- whole_static_libs: ["libc_unwind_static"],
-
system_shared_libs: [],
// Opt out of native_coverage when opting out of system_shared_libs
@@ -475,35 +464,6 @@
}
cc_library {
- // NOTE: --exclude-libs=libgcc.a makes sure that any symbols ld-android.so pulls from
- // libgcc.a are made static to ld-android.so. This in turn ensures that libraries that
- // a) pull symbols from libgcc.a and b) depend on ld-android.so will not rely on ld-android.so
- // to provide those symbols, but will instead pull them from libgcc.a. Specifically,
- // we use this property to make sure libc.so has its own copy of the code from
- // libgcc.a it uses.
- //
- // DO NOT REMOVE --exclude-libs!
-
- ldflags: [
- "-Wl,--exclude-libs=libgcc.a",
- "-Wl,--exclude-libs=libgcc_stripped.a",
- "-Wl,--exclude-libs=libclang_rt.builtins-arm-android.a",
- "-Wl,--exclude-libs=libclang_rt.builtins-aarch64-android.a",
- "-Wl,--exclude-libs=libclang_rt.builtins-riscv64-android.a",
- "-Wl,--exclude-libs=libclang_rt.builtins-i686-android.a",
- "-Wl,--exclude-libs=libclang_rt.builtins-x86_64-android.a",
- ],
-
- // for x86, exclude libgcc_eh.a for the same reasons as above
- arch: {
- x86: {
- ldflags: ["-Wl,--exclude-libs=libgcc_eh.a"],
- },
- x86_64: {
- ldflags: ["-Wl,--exclude-libs=libgcc_eh.a"],
- },
- },
-
srcs: ["ld_android.cpp"],
cflags: [
"-Wall",