[cfe-dev] Adding -fuse-ld= support to clang
Rafael Espíndola
rafael.espindola at gmail.com
Sat May 18 08:59:32 PDT 2013
On 18 May 2013 11:00, David Chisnall <David.Chisnall at cl.cam.ac.uk> wrote:
> Hi Everyone,
>
> In FreeBSD, we are about to start the process of migrating from (ancient) BFD ld to MCLinker, so we're going to need support for multiple linkers for a while. It turns out that gcc already has an option to select linkers, so I have attempted to remain compatible in the attached patch. This adds a -fuse-ld={name} option, which takes a string as an argument. The toolchains then request a linker and get either ld.{name}, ld-{name}, or {name} as the linker.
>
> Does anyone have objections to committing this as-is, or would anyone like to recommend a better approach?
Looks fairly reasonable, but
* Instead of running touch, add the file to the install tree in svn.
* Test both ld.name and ld-name.
* If there is both ld.name and ld-name, make sure and test we select
the same one as gcc.
> David
>
> Index: include/clang/Basic/DiagnosticDriverKinds.td
> ===================================================================
> --- include/clang/Basic/DiagnosticDriverKinds.td (revision 182184)
> +++ include/clang/Basic/DiagnosticDriverKinds.td (working copy)
> @@ -26,6 +26,8 @@
> "unsupported runtime library '%0' for platform '%1'">;
> def err_drv_invalid_stdlib_name : Error<
> "invalid library name in argument '%0'">;
> +def err_drv_invalid_linker_name : Error<
> + "invalid linker name in argument '%0'">;
> def err_drv_invalid_opt_with_multiple_archs : Error<
> "option '%0' cannot be used with multiple -arch options">;
> def err_drv_invalid_output_with_multiple_archs : Error<
> Index: include/clang/Driver/Options.td
> ===================================================================
> --- include/clang/Driver/Options.td (revision 182184)
> +++ include/clang/Driver/Options.td (working copy)
> @@ -744,6 +744,8 @@
> def fuse_cxa_atexit : Flag<["-"], "fuse-cxa-atexit">, Group<f_Group>;
> def fuse_init_array : Flag<["-"], "fuse-init-array">, Group<f_Group>, Flags<[CC1Option]>,
> HelpText<"Use .init_array instead of .ctors">;
> +def fuse_ld_EQ : Joined<["-", "--"], "fuse-ld=">, Group<f_Group>,
> + HelpText<"The linker to use.">;
> def fverbose_asm : Flag<["-"], "fverbose-asm">, Group<f_Group>;
> def fvisibility_EQ : Joined<["-"], "fvisibility=">, Group<f_Group>,
> HelpText<"Set the default symbol visibility for all global declarations">;
> Index: include/clang/Driver/ToolChain.h
> ===================================================================
> --- include/clang/Driver/ToolChain.h (revision 182184)
> +++ include/clang/Driver/ToolChain.h (working copy)
> @@ -136,6 +136,9 @@
>
> std::string GetFilePath(const char *Name) const;
> std::string GetProgramPath(const char *Name) const;
> + /// Returns the linker path, respecting the -fuse-ld= argument to determine
> + /// the linker suffix or name.
> + std::string GetLinkerPath() const;
>
> // Platform defaults information
>
> Index: lib/Driver/ToolChain.cpp
> ===================================================================
> --- lib/Driver/ToolChain.cpp (revision 182184)
> +++ lib/Driver/ToolChain.cpp (working copy)
> @@ -132,6 +132,36 @@
>
> }
>
> +std::string ToolChain::GetLinkerPath() const {
> + if (Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
> + StringRef Value = A->getValue();
> + // If we're passed -fuse-ld= with no argument, or with the argument ld,
> + // then use whatever the default system linker is.
> + if (Value.empty() || Value == "ld")
> + return GetFilePath("ld");
> + std::string LinkerName = Value.str();
> + std::string LD("ld.");
> + LD += LinkerName;
> + std::string LinkerPath = GetFilePath(LD.c_str());
> + bool Exists;
> + if (!llvm::sys::fs::exists(LinkerPath, Exists) && Exists)
> + return LinkerPath;
> + LD = std::string("ld-") + LinkerName;
> + LinkerPath = GetFilePath(LD.c_str());
> + if (!llvm::sys::fs::exists(LinkerPath, Exists) && Exists)
> + return LinkerPath;
> + LinkerPath = GetFilePath(LinkerName.c_str());
> + if (!llvm::sys::fs::exists(LinkerPath, Exists) && Exists)
> + return LinkerPath;
> + getDriver().Diag(diag::err_drv_invalid_linker_name)
> + << A->getAsString(Args);
> + // Fall through and run the system linker - we could do a hard error here,
> + // but we may as well try and see if it works.
> + }
> + return GetFilePath("ld");
> +}
> +
> +
> std::string ToolChain::GetProgramPath(const char *Name) const {
> return D.GetProgramPath(Name, *this);
> }
> Index: lib/Driver/Tools.cpp
> ===================================================================
> --- lib/Driver/Tools.cpp (revision 182184)
> +++ lib/Driver/Tools.cpp (working copy)
> @@ -5219,8 +5219,7 @@
> getToolChain().GetFilePath("crtendS.o")));
> }
>
> - const char *Exec =
> - Args.MakeArgString(getToolChain().GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> @@ -5361,8 +5360,7 @@
> getToolChain().GetFilePath("crtendS.o")));
> }
>
> - const char *Exec =
> - Args.MakeArgString(getToolChain().GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> @@ -5612,8 +5610,7 @@
>
> addProfileRT(ToolChain, Args, CmdArgs, ToolChain.getTriple());
>
> - const char *Exec =
> - Args.MakeArgString(ToolChain.GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> @@ -5762,7 +5759,7 @@
>
> addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
>
> - const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> @@ -6247,7 +6244,7 @@
> Args.MakeArgString(getToolChain().GetFilePath("crtend.o")));
> }
>
> - const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> @@ -6430,8 +6427,7 @@
>
> addProfileRT(getToolChain(), Args, CmdArgs, getToolChain().getTriple());
>
> - const char *Exec =
> - Args.MakeArgString(getToolChain().GetProgramPath("ld"));
> + const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
> C.addCommand(new Command(JA, *this, Exec, CmdArgs));
> }
>
> Index: test/Driver/fuse_ld.c
> ===================================================================
> --- test/Driver/fuse_ld.c (revision 0)
> +++ test/Driver/fuse_ld.c (working copy)
> @@ -0,0 +1,7 @@
> +// RUN: rm -f ld.foo
> +// RUN: %clang %s -target i386-unknown-freebsd -fuse-ld=foo -### 2>&1 | FileCheck -check-prefix=MISSING %s
> +// RUN: touch ld.foo
> +// RUN: %clang %s -B. -target i386-unknown-freebsd -fuse-ld=foo -### 2>&1 | FileCheck -check-prefix=FOUND %s
> +
> +// CHECK-MISSING: error: invalid linker name in argument '-fuse-ld=foo'
> +// CHECK-FOUND: "./ld.foo"
>
>
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