Default clang to use lld on specific conditions (#340)

* Default clang to use lld on specific conditions

* Add test to check clang linker flags on non freebsd

* Update src/Runner.jl

Co-authored-by: Mosè Giordano <giordano@users.noreply.github.com>

---------

Co-authored-by: Mosè Giordano <giordano@users.noreply.github.com>

Author: gbaraldi

src/Runner.jl

@@ -187,6 +187,7 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
 
     target = aatriplet(platform)
     host_target = aatriplet(host_platform)
+    clang_use_lld = (!isnothing(gcc_version) && !isnothing(clang_version) && clang_version >= v"16" && gcc_version >= v"5")
 
     function wrapper(io::IO,
                      prog::String;
@@ -343,7 +344,7 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
             ])
             end
         end
-        if Sys.islinux(p) && !isnothing(gcc_version) && (clang_version >= v"16")
+        if Sys.islinux(p) && !isnothing(gcc_version) !isnothing(clang_version) && (clang_version >= v"16")
             append!(flags, ["--gcc-install-dir=/opt/$(aatriplet(p))/lib/gcc/$(aatriplet(p))/$(gcc_version)"])
         end
         if Sys.iswindows(p)
@@ -409,6 +410,7 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
             append!(flags, get_march_flags(arch(p), march(p), "clang"))
         end
         if Sys.isapple(p)
+            macos_version_flags = clang_use_lld ? (min_macos_version_flags()[1],) : min_macos_version_flags()
             append!(flags, String[
                 # On MacOS, we need to override the typical C++ include search paths, because it always includes
                 # the toolchain C++ headers first.  Valentin tracked this down to:
@@ -421,7 +423,7 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
                 # `clang` as a linker (and we have no real way to detect that in the wrapper), which will
                 # cause `clang` to complain about compiler flags being passed in.
                 "-Wno-unused-command-line-argument",
-                min_macos_version_flags()...,
+                macos_version_flags...,
             ])
         end
         sanitize_compile_flags!(p, flags)
@@ -467,7 +469,9 @@ function generate_compiler_wrappers!(platform::AbstractPlatform; bin_path::Abstr
         end
         # we want to use a particular linker with clang.  But we want to avoid warnings about unused
         # flags when just compiling, so we put it into "linker-only flags".
-        push!(flags, "-fuse-ld=$(aatriplet(p))")
+        if !clang_use_lld
+            push!(flags, "-fuse-ld=$(aatriplet(p))")
+        end
 
         sanitize_link_flags!(p, flags)
 

test/rootfs.jl

@@ -223,10 +223,17 @@ end
             clang = read(joinpath(platform_bin_dir, "clang"), String)
             # Check link flags
             @test occursin("-L/opt/$(triplet(platform))/$(triplet(platform))/lib", clang)
-            @test occursin("fuse-ld=$(triplet(platform))", clang)
             # Other compilers
             @test occursin("GOOS=\"freebsd\"", read(joinpath(platform_bin_dir, "go"), String))
             @test occursin("--target=x86_64-unknown-freebsd", read(joinpath(platform_bin_dir, "rustc"), String))
         end
+        platform = Platform("x86_64", "linux"; libc="glibc", cxxstring_abi="cxx11")
+        mktempdir() do bin_path
+            platform_bin_dir = joinpath(bin_path, triplet(platform))
+            generate_compiler_wrappers!(platform; bin_path = bin_path, compilers = [:c], gcc_version=v"5")
+            clang = read(joinpath(platform_bin_dir, "clang"), String)
+            # Check link flags
+            @test occursin("-L/opt/$(aatriplet(platform))/lib/gcc/opt/$(aatriplet(platform))/lib/gcc", clang)
+        end
     end
 end

test/runners.jl

@@ -126,6 +126,11 @@ end
     # This tests only that compilers for all platforms can build and link simple C code
     @testset "Compilation - $(platform) - $(compiler)" for platform in platforms, compiler in ("cc", "gcc", "clang")
         mktempdir() do dir
+            # if compiler == "clang"
+            #     ur = preferred_runner()(dir; platform=platform, preferred_gcc_version=v"5") #TODO: Fix CI disk size issues to allow this
+            # else
+            #     ur = preferred_runner()(dir; platform=platform)
+            # end
             ur = preferred_runner()(dir; platform=platform)
             iobuff = IOBuffer()
             test_c = """